NC State
BioResources
  • Editorialpp 2964-2967Barrett, T. (2016)."Enzymatic pretreatment during 15th to 18th century papermaking in Europe," BioRes. 11(2), 2964-2967.AbstractArticlePDF

    Enzymatic pretreatment of cellulose is generally considered to be a new area of research, but in fact it was a standard step in European pre-industrial papermaking between 1300 and 1800. Specialized handmade papers are routinely prepared in our Center for use in the care and conservation of rare books and manuscripts. Our attempts to replicate some of the early papers have led us to an investigation of retting (or fermentation) of hemp and cotton fiber as a pre-beating step. Results of twenty-two production runs show that increased fermentation time gives increased Canadian Standard Freeness and improved formation quality while permitting a decrease in beating time.

  • Editorialpp 2968-2971Cratty, C. (2016). "The artistic possibilities of cellulosic fibers," BioRes. 11(2), 2968-2971.AbstractArticlePDF

    Plant fibers have been used for over 2,000 years to make paper. When the process of hand papermaking paled, I set out to find a way to use cellulosic fibers as paint. A decade of experimenting led to the choice of 3 main fibers that worked best. Methods of cooking, preparing, coloring, and drying were tested and refined. Using pulp as paint brought me the innovative techniques I developed in this new craft medium and led to recognition as a Tennessee Master Craft Artist. I continue to experiment with new ways to use pulp as paint.

  • Researchpp 2972-2986Tondi, G., Link, M., Kolbitsch, C., Gavino, J., Luckeneder, P., Petutschnigg, A., Herchl, R., and Van Doorslaer, C. (2016). "Lignin-based foams: Production process and characterization," BioRes. 11(2), 2972-2986.AbstractArticlePDF

    Lignin foams are innovative materials obtained by the copolymerization of furanics with the spent liquor from the magnefite wood pulping process. In this study, the influence of the component amount in the formulation, as well as the effect of temperature on the final product, were elucidated. Several formulations, with various lignin/furanic ratios, blowing agents, and catalyst concentrations, exhibited good homogeneity and densities between 185 and 407 kg m-3. The mechanical properties, as well as the thermal conductivities, confirmed the strong dependence on density, and the results obtained were comparable to that of tannin foams. The leaching tests revealed that the lignin foams released a certain amount of catalyst within the first minutes of water dipping. However the pH of this leachate stabilized quickly, which suggests that the catalyst can be easily recovered.

  • Researchpp 2987-2997Veisi, A., and Mahdavi, S. (2016). "Mixing bleached white poplar and wheat straw chemimechanical pulps to improve the mechanical and optical characteristics," BioRes. 11(2), 2987-2997.AbstractArticlePDF

    The aim of this study was to determine the optimum combination of wheat straw and white poplar (P. alba) chemimechanical pulps (CMPs) for producing newsprint paper. The CMP was prepared separately from the two raw materials. Cooking conditions included 10%, 12%, and 14% chemical charge based on w/w oven dry raw materials, maximum cooking temperatures of 120, 140, and 160 °C, and cooking time of 45 min. Hydrogen peroxide was used for bleaching the selected pulp. The results indicated that screened pulp yields were in the range of 54.3% to 61% and 80.9% to 85.9% for 18 cooking trials of wheat straw and white poplar, respectively. Handsheet brightness reached up to 52.9% and 61.9% for wheat straw and white poplar, respectively. The highest breaking length and burst index were related to CMP produced from 25% white poplar/75% wheat straw pulp blend. The best tear index was obtained using a mixture of 50% white poplar and 50% wheat straw pulp. Averages of breaking length, burst and tear indices ranged between 4.61 and 3.80 km, 2.31 and 2.55 kPa•m2/g, and 7.29 and 11.1 mN•m2/g, respectively. The strength properties of handsheets were higher than those reported for commercial newsprint except the breaking length of 50%/50% blend.

  • Researchpp 2998-3012Wang, Q., Zhang, C., Lu, L., Yao, R., Xu, S., and Wang, Y. (2016). "Optimization of biobutanol production from poplar wood hydrolysate using a mutant of Clostridium saccharobutylicum," BioRes. 11(2), 2998-3012.AbstractArticlePDF

    Enzymatic hydrolysate of poplar wood was used in this study to produce biobutanol by a mutant M-18. Plackett-Burman and Box-Behnken designs were adopted in order to screen crucial factors from various nutrient factors affecting butanol production. These factors included reducing sugar content of hydrolysate, MgSO4•7H2O, yeast extract, K2HPO4, FeSO4•7H2O, CaCO3, and ammonium sulfate. The results demonstrated that a reduction in sugar content, K2HPO4, and CaCO3 were the most critical factors. Yeast extract was also found to have a significant effect on biobutanol production by performing an analysis of variance (ANOVA). Optimal variables were 44.53 g/L of reducing sugar concentration, 1.36 g/L of K2HPO4, and 4.65 g/L of CaCO3 according to the Box-Behnken design. A model was established and used to predict a maximum biobutanol production of 7.59 g/L. Optimal conditions of fermentation were determined by orthogonal tests. Three distinct factors with important effects on biobutanol production were explored. The pH was identified as having the most significant effect on biobutanol biosynthesis. Optimized fermentation conditions for biobutanol production were determined at an initial pH of 6.5, temperature 36 °C, and inoculum quantity 9%. Under these conditions, a maximum biobutanol production of 8.41±0.20 g/L was achieved in verification experiments in a 3 L fermentation tank.

  • Researchpp 3013-3026Owolabi, A. W. T., Arniza, G., wan Daud, W., and Alkharkhi, A. F. M. (2016). "Effect of alkaline peroxide pre-treatment on microfibrillated cellulose from oil palm fronds rachis amenable for pulp and paper and bio-composite production," BioRes. 11(2), 3013-3026.AbstractArticlePDF

    Effects of alkaline peroxide (AP) pre-treatment were investigated with respect to the extracted cellulose fibres from the vascular bundles of oil palm (Elaeis guineensis) fronds (OPF) rachis at different AP concentrations. The extracted fibres were prepared through the mechanical fibrillation resulting from the AP pre-treatment concentrations of the rachis. The cellulose fibres obtained were characterized using microscopic (SEM), spectroscopic (FTIR), thermal (TGA-DTG), and X-ray diffraction (XRD) techniques. The screen pulp yield was between 38.07% and 42.69%, which increased with the increase in the AP concentrations. The SEM showed a significant separation of the fibres after the AP pretreatment. FTIR spectroscopy and TGA showed significant dissolution of both lignin and hemicellulose molecules from the treated biomass at higher alkaline peroxide concentrations. The thermal stability of the extracted fibres ranged from 366 oC to 392 °C while the XRD results showed that the cellulose fibre extracted at H2O2/NaOH ratio of 2.5%: 2.0%,w/v AP concentrations gave the highest percentage crystallinity (35.7%). The handsheet made from the cellulose fibre showed that tensile, burst, and tear indexes increased with an increase in AP concentration. Duncan Multiple Range Test shows that mild alkaline peroxide pretreatment (medium concentrations) is best favoured for paper making pulp and bio-composite production.

  • Researchpp 3027-3037Roszyk, E., Moliński, W., and Kamiński, M. (2016). "Tensile properties along the grains of earlywood and latewood of Scots pine (Pinus sylvestris L.) in dry and wet state," BioRes. 11(2), 3027-3037.AbstractArticlePDF

    Mechanical parameters of Scots pine wood (Pinus sylvestris L.) of low (about 8%) and high (higher than the fiber saturation point) moisture content (MC) subjected to tensile stress along the grains were studied. The measurements were performed for microtome samples sliced from either earlywood or latewood and for samples containing both earlywood and latewood. The effect of MC on the mechanical properties of earlywood and latewood of Scots pine was different. The MC was found to have greater influence on the tensile strength and modulus of elasticity in latewood than in earlywood, but its effect on strain at failure was greater in earlywood. As determined individually for earlywood and latewood, the tensile strength, modulus of elasticity, and the strain at failure that were calculated from the rule of mixtures (the weighted mean for earlywood and latewood) did not differ significantly from the values found in the samples containing both zones. This similarity was observed at low and high MC.

  • Researchpp 3038-3048Sun, X., Wang, Z., Liu, Y., and Yang, G. (2016). "Chromium(VI) removal by Fe(III)-loaded succinylated mercerized cellulose from aqueous solution," BioRes. 11(2), 3038-3048.AbstractArticlePDF

    A new chelating material from mercerized cotton linter was prepared by a reaction with succinic anhydride in the presence of toluene/triethylamine and a 4-dimethylaminopyridine catalyst, followed by reacting with Fe(III) to obtain the final product. The materials were characterized by Fourier transform infrared spectrometry, scanning electron microscopy, and energy dispersive spectrometer; the adsorption of chromium(VI) from an aqueous solution was examined. The Langmuir isotherm accurately fit the experimental data, and the calculated adsorption ability of Fe(III)-loaded adsorbent for chromium(VI) was 11.1 mg/g. The adsorption process followed a pseudo-second-order kinetic model.

  • Researchpp 3049-3072Essoua Essoua, G. G., Blanchet, P., Landry, V., and Beauregard, R. (2016). "Pine wood treated with a citric acid and glycerol mixture: Biomaterial performance improved by a bio-byproduct," BioRes. 11(2), 3049-3072.AbstractArticlePDF

    Wood material is a good reservoir for biogenic carbon storage. The use of wood material for outdoor products such as siding in the building construction sector presents limits. These limits are bound to the nature of wood material (hygroscopic property and anatomical structure). They are responsible for the dimensional variation associated with moisture content variations. Fungal attacks and coating layers adhesion on wood surface, are other problems. This research investigated the feasibility of impregnation with environmentally friendly chemicals, i.e., a citric acid-glycerol mixture (CA-G). The anti-swelling efficiency (ASE), hardness, biodegradation, and coating adhesion tests were performed on softwood specimens. ASE results were up to 53%. The equilibrium moisture content of the treated specimens was less than half of the untreated ones. FTIR spectroscopy showed bands at 1720 to 1750 cm-1, indicating the presence of ester bonds, and scanning electron microscopy images confirmed the polymerization and condensation of treatment solution inside the wood structure. Hardness and decay resistance were increased; however, treatment reduces coating adhesion. In conclusion, CA-G represents a promising eco-responsible solution for improving the technical performance of outdoor wood products.

  • Researchpp 3073-3083Li, H., Deng, Y., Liang, J., Dai, Y., Liu, B., Ren, Y., Qiu, X., and Li, C. (2016). "Direct preparation of hollow nanospheres with kraft lignin: A facile strategy for effective utilization of biomass waste," BioRes. 11(2), 3073-3083.AbstractArticlePDF

    This work discusses the preparation and characterization of hollow nanospheres based on kraft lignin (KL). Kraft lignin is a by-product of the papermaking industry and an abundant renewable resource. It was determined that adding water to a KL/THF solution induced KL to form hollow nanospheres via self-assembly. Scanning electron microscopy and transmission electron microscopy confirmed the hollow nanosphere morphology. The shell thickness of the hollow nanospheres was tunable by adjusting the initial KL concentration in THF, making the nanospheres a potential material for the encapsulation and controlled release of guest molecules. Ultraviolet (UV) and Fourier transform infrared (FTIR) spectroscopy confirmed the π-π stacking of aromatic rings as an important and distinctive mechanism for the formation of hollow KL nanospheres. The nanospheres were obtained simply and inexpensively, and they exhibited the characteristics of biocompatibility, biodegradability, and low toxicity. These advantages make hollow KL nanospheres attractive for applications in nanoscience and nanotechnology. This study developed an economically feasible and facile strategy for the effective use of biomass waste in sustainable chemistry.

  • Researchpp 3084-3093Wang, W., Wang, J., Shi, X., Yu, Z., Song, Z., Dong, L., Jiang, G., and Han, S. (2016). "Synthesis of mesoporous TiO2 induced by nano-cellulose and its photocatalytic properties," BioRes. 11(2), 3084-3093.AbstractArticlePDF

    Nano-cellulose was prepared via acid hydrolysis and cell crushing using microcrystalline cellulose as the raw material. Mesoporous TiO2 was then prepared via hydrothermal synthesis using butyl titanate as the titanium source and the previously prepared nano-cellulose as the template. It is confirmed by FT-IR and XRD that the commercial product P25 consisted of anatase and rutile mixed crystal structure, in which the content of anatase and rutile was 80.5% and 19.5%, respectively. The prepared TiO2 had an anatase single crystal structure. XPS analysis showed an elemental content of C, O, and Ti with two kinds of TiO2. TEM, HRTEM, and electron diffraction were used to characterize the particle size of the prepared mesoporous TiO2, mainly concentrated in the 10 to 20 nm range. Crystalline spacing was 0.35 nm (101). By comparison, the particle size of P25 was mainly distributed in the 15 to 25 nm range with a crystalline spacing of 0.35 (101) and 0.32 nm (110) respectively. XRD analysis was consistent with the results. Based on N2 adsorption-desorption isotherm curves it was evident that the surface area of prepared TiO2 and P25 was 38.92 m2/g and 53.54 m2/g, the cumulative pore volume of the two is 0.24 m2/g and 0.17 m2/g respectively. The experiments of photocatalytic degradation of rhodamine B showed that the catalytic ability of the prepared mesoporous TiO2 to degrade pollutants was better than commercial TiO2 under UV irradiation.

  • Researchpp 3094-3109Shen, Z., Yu, X., and Chen, J. (2016). "Production of 5-hydroxymethylfurfural from fructose catalyzed by sulfonated bamboo-derived carbon prepared by simultaneous carbonization and sulfonation," BioRes. 11(2), 3094-3109.AbstractArticlePDF

    A novel sulfonated bamboo-derived carbon (SBC) was prepared through a one-pot simultaneous carbonization and sulfonation method using p-toluenesulfonic acid as the sulfonating agent. This method was used in place of the two-step method of high temperature carbonization followed by sulfonation, in order to reduce energy consumption and avoid the use of substantial amounts of strong liquid acid. The as-prepared catalyst bearing SO3H, COOH, and phenolic OH groups demonstrated efficient catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural (HMF), achieving 92.1% HMF yield in a mixture of tetrahydrofuran (THF) and dimethylsulfoxiden (DMSO) (volume ratio of THF/DMSO 3/7). The mixture had a fructose concentration of 0.08 g·mL-1 with a catalyst amount of 10% weight of fructose at 140 °C in 60 min. No distinct activity drop was observed after the initial deactivation during 5 recycling runs, confirming a good stability of the prepared catalyst. Moreover, kinetic data showed that SBC promoted fructose dehydration to HMF may follow pseudo-first order kinetics with the activation energy of 43.6 kJ·mol-1 under investigated conditions. The convenient catalyst preparation method and excellent catalytic performance of the catalyst provide an easy-handling and eco-friendly strategy for crude biomass utilization in catalyst production.

  • Researchpp 3110-3122Zhou, H., Xu, R., and Ma, E. (2016)."Effects of removal of chemical components on moisture adsorption by wood," BioRes. 11(2), 3110-3122.AbstractArticlePDF

    To investigate the effects on moisture sorption behavior of wood caused by the removal of chemical components, Populus euramericana flour (40 to 60 mesh) was divided into four groups: untreated, extractives removed, hemicellulose removed, and matrix removed. The samples at the fiber saturation point and under oven-dried conditions were separately exposed to relative humidities of 11%, 45%, and 75% at 25 °C for desorption and adsorption. Additionally, moisture changes were measured during the processes. The results showed that moisture changed rapidly for all four groups at the initial stage during sorption, after which the rate gradually decreased until a steady-state equilibrium was reached. Among the four groups, the samples from which extractives had been removed exhibited the highest moisture content and moisture sorption coefficient, followed by the untreated samples, hemicellulose removed, and matrix removed samples. With increasing relative humidity, the hysteresis ratio A/D of the samples increased, indicating a reduction in sorption hysteresis, which was further decreased by hemicellulose extraction.

  • Researchpp 3123-3135Luppold, W. G., and Bumgardner, M. S. (2016). "Employment changes in U.S. hardwood lumber consuming industries during economic expansions and contractions since 1991," BioRes. 11(2), 3123-3135.AbstractArticlePDF

    Understanding employment trends is important for discerning the economic vitality of U.S. hardwood lumber users. After a period of growth in the 1990s, employment in industries consuming hardwood lumber has declined in the 21st century. The wood household furniture industry has experienced the greatest decline, with North Carolina, Virginia, and California being the states most affected. Nearly all of the decline in employment in the furniture industry can be attributed to increased importation of this product. Millwork and kitchen cabinets are industries associated with home construction. Both of these industries experienced declines in employment in the 21st century. Employment in millwork started to decline after 2000, while employment in the kitchen cabinet industry started to decline after 2006. While there was little change in the relative regional employment rankings in the millwork industry, Indiana displaced California and Texas to become the largest employer in the kitchen cabinet industry. Employment in the pallet industry has declined in the 21st century, but mostly during the two recessionary periods. The pallet industry was the only industry that had an employment increase after 2009. Ohio was once the major pallet producing state, but it was displaced by California and Texas after 2002.

  • Researchpp 3136-3152Runtti, H., Tuomikoski, S., Kangas, T., Kuokkanen, T., Rämö, J., and Lassi, U. (2016). "Sulphate removal from water by carbon residue from biomass gasification: Effect of chemical modification methods on sulphate removal efficiency," BioRes. 11(2), 3136-3152.AbstractArticlePDF

    Sulphate removal from mine water is a problem because traditional chemical precipitation does not remove all sulphates. In addition, it creates lime sediment as a secondary waste. Therefore, an inexpensive and environmental-friendly sulphate removal method is needed in addition to precipitation. In this study, carbon residues from a wood gasification process were repurposed as precursors to a suitable sorbent for SO42- ion removal. The raw material was modified using ZnCl2, BaCl2, CaCl2, FeCl3, or FeCl2. Carbon residues modified with FeCl3 were selected for further consideration because the removal efficiency toward sulphate was the highest. Batch sorption experiments were performed to evaluate the effects of the initial pH, initial SO42- ion concentration, and contact time on sulphate removal. The removal of SO42- ions using Fe-modified carbon residue was notably higher compared with unmodified carbon residue and commercially available activated carbon. The sorption data exhibited pseudo-second-order kinetics. The isotherm analysis indicated that the sorption data of Fe-modified carbon residues can be represented by the bi-Langmuir isotherm model.

  • Researchpp 3153-3164Tufan, M., Güleç, T., Peşman, E., and Ayrilmis, N. (2016). "Technological and thermal properties of thermoplastic composites filled with heat-treated alder wood," BioRes. 11(2), 3153-3164.AbstractArticlePDF

    This study investigated the effect of heat-treated wood content on the water absorption, mechanical, and thermal properties of wood plastic composites (WPCs). The WPCs were produced from various loadings (30, 40, and 50 wt%) of heat-treated and untreated alder wood flours (Alnus glutinosa L.) using high-density polyethylene (HDPE) with 3 wt% maleated polyethylene (MAPE) coupling agent. All WPC formulations were compression molded into a hot press for 3 min at 170 ºC. The WPCs were evaluated using mechanical testing, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The mechanical property values of the WPC specimens decreased with increasing amounts of the heat-treated wood flour, except for the tensile modulus values. The heat treatment of alder wood slightly increased the thermal stability of the WPCs compared with the reference WPCs. The crystallization degree (Xc) and the enthalpy of crystallization of the WPCs slightly decreased with increasing content of the heat-treated wood flour. However, all WPCs containing the heat-treated alder wood flour showed a higher crystallinity degree than that of the virgin HDPE.

  • Researchpp 3165-3177Long, L., Shi, H., Li, X., Zhang, Y., Hu, J., and Wang, F. (2016). "Cloning, purification, and characterization of a thermostable β-glucosidase from Thermotoga thermarum DSM 5069," BioRes. 11(2), 3165-3177.AbstractArticlePDF

    A 56-kDa β-glucosidase (TthBgl) derived from Thermotoga thermarum DSM 5069 was expressed and purified from Escherichia coli BL21 (DE3). The purified enzyme showed hydrolytic activity towards only p-nitrophenyl-β-D-glucopyranoside among the synthetic glycosides tested. The pH maximum was 5.0, and under the conditions tested, maximal activity was at 85 ºC, and pH stability occurred from 5.0 to 6.0. After being incubated at 80 ºC for 120 min, TthBgl retained 80% of its original activity. The β-glucosidase had no apparent requirement for metal ions or other co-factors, but its activity was significantly inhibited by 0.1% SDS and 1mM Cu2+, in which only 3% and 10% residual activity was maintained, respectively. The Vmax of TthBgl was 8.79 U mg-1 for p-nitrophenyl-β-D-glucopyranoside, while the Km was 2.41 mM. The Enzyme activity was gradually inhibited by the addition of glucose, but remained approximately 50% of its original value in 500 mM glucose. 789.25 mg/L glucose was released from cellobiose by the incubation of 0.2 U/mL TthBgl for 9 h at 75 ºC. According to a phylogenetic analysis, TthBgl belongs to the glycosyl hydrolase family 3 (GH3).

  • Researchpp 3178-3190Liu, Z., Huang, Y., and Zhao, G. (2016). "Preparation and characterization of activated carbon fibers from liquefied wood by ZnCl2 activation," BioRes. 11(2), 3178-3190.AbstractArticlePDF

    In this study, activated carbon fibers (ACFs) were prepared from liquefied wood by chemical activation with ZnCl2, with a particular focus on the effects of temperature and ZnCl2: liquefied wood-based fiber (LWF) ratio on yield, porous texture, and surface chemistry. The characterization and properties of these ACFs were investigated by nitrogen adsorption/desorption, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). When using a 6:1 impregnation ratio, the specific surface area (SBET) of the resultant ACFs was as high as 1423 m2/g. The effect of an increase in impregnation ratio on the porosity of ACFs was stronger than that of an increase in the activation temperature. However, the former had a weaker impact on the surface chemistry and structure. It was also found that the yields of ACFs obtained by ZnCl2 activation were higher than those obtained by physical activation. Besides, the prepared ACFs presented higher adsorption than other raw materials in the adsorption test, indicating that ACFs prepared from LWF by ZnCl2 activation could be used as an adsorbent for the adsorption of medium size organic compounds.

  • Researchpp 3191-3203Zhou, Z., Cheng, Y., Zhang, W., Jiang, J., and Lei, F. (2016). "Characterization of lignins from sugarcane bagasse pretreated with green liquor combined with ethanol and hydrogen peroxide," BioRes. 11(2), 3191-3203.AbstractArticlePDF

    Sugarcane bagasse was pretreated by green liquor combined with ethanol (GL-Ethanol) and green liquor combined with H2O2 (GL-H2O2). After 72 h of enzymatic hydrolysis, the glucose yields of sugarcane bagasse pretreated with GL-Ethanol and GL-H2O2 were 97.7% and 41.7%, respectively. The reason that GL-Ethanol was more effective than GL-H2O2 has not been elucidated clearly. In this study, the chemical composition of the sugarcane bagasse and chemical structure of the isolated lignins after these two pretreatment methods were characterized to investigate their correlation with the enzymatic hydrolysis of sugarcane bagasse. The removal of lignins with GL-Ethanol pretreatment was much higher than that of GL-H2O2. In addition, the decomposition of cellulose was lower in the case of GL-Ethanol than in that of GL-H2O2. According to Fourier transform infrared spectroscopy (FT-IR) and 1H-nuclear magnetic resonance (NMR) studies, the ester bonds (belonging to lignin-carbohydrate complex) could be broken during GL-Ethanol treatment. It was also found that the molecular weight of lignins obtained from GL-Ethanol was lower than that of lignins from GL-H2O2.

  • Researchpp 3204-3214Dai, Y., Song, X., Gao, C., He, S., Nie, S., and Qin, C. (2016). "Xylanase-aided chlorine dioxide bleaching of bagasse pulp to reduce AOX formation," BioRes. 11(2), 3204-3214.AbstractArticlePDF

    Xylanase pretreatment was used to improve the chlorine dioxide bleaching of bagasse pulp. The pulp was pretreated with xylanase, which was followed by a chlorine dioxide bleaching stage. The HexA content of the pulp and the AOX content of the bleaching effluent were measured using UV-Vis and GC-MS methods, respectively. The results showed that a good correlation occurred between HexA and kappa number. HexA content of the pulp decreased significantly after the xylanase pretreatment. The AOX content of the bleaching effluent decreased as HexA was removed from the pulp. It was found that AOX could be reduced by up to 29.8%, comparing XD0 with a D0 stage. Fourier transform infrared spectroscopy (FTIR) was employed to determine the breakage of chemical bonds in the pulp. It revealed that some lignin and hemicellulose were removed after xylanase treatment. The GC-MS results showed that some toxic chloride such as 2,4,6-trichlorophenol could be completely removed after xylanase pretreatment.

  • Researchpp 3215-3229Pelit, H., Budakçı, M., and Sönmez, A. (2016). "Effects of heat post-treatment on dimensional stability and water absorption behaviours of mechanically densified Uludağ fir and black poplar woods," BioRes. 11(2), 3215-3229.AbstractArticlePDF

    One of the most persistent problems with mechanically densified wood is its inherent dimensional instability. The effects of heat post-treatment on the changes in spring-back (SB), compression ratio recovery (CRR), thickness swelling (TS), and water absorption (WA) of newly-tested Uludağ fir (Abies bornmuelleriana Mattf.) and black poplar (Populus nigra L.) wood samples that had been thermo-mechanically densified were investigated. Samples were densified with compression ratios of 25% and 50% with temperatures of 100 and 140 °C, respectively. Then, the heat post-treatment was applied to the samples at 185 and 212 °C for 2 h. For the two newly-tested wood types, results of the preliminary study show that SB and TS were higher at a 50% compression ratio compared with 25%. Regarding densification temperature, TS was lower in samples densified at 140 °C, while SB was higher. WA values were lower in compressed samples (50%) at high rates. The effect of the densification temperature on WA was insignificant. Heat post-treatment had a considerable effect on the dimensional stability and hygroscopicity of the densified Uludağ fir and black poplar samples. With an increase in heat treatment temperature, the dimensional stability increased, while the hygroscopicity of densified samples decreased. As a result of heat post-treatment applied at 212 °C, SB, CRR, TS, and WA decreased by 88%, 85%, 79%, and 53%, respectively.

  • Researchpp 3230-3243Mirmohamadsadeghi, S., Karimi, K., and Horváth, I. S. (2016). "Improvement of solid-state biogas production from wood by concentrated phosphoric acid pretreatment," BioRes. 11(2), 3230-3243.AbstractArticlePDF

    Cellulose solvent- and organic solvent-based lignocellulose fractionation (COSLIF) has been repeatedly shown to be a cost-effective and promising process to modify the structure of different lignocelluloses. It has been repeatedly reported to improve enzymatic hydrolysis and ethanol production from different lignocelluloses. In this study, COSLIF was used to improve biomethane production from pine (softwood), poplar (soft hardwood), and berry (hard hardwood) via solid state anaerobic digestion (SSAD). Feed to inoculum (F/I) ratio, which plays a major role in SSAD, was set to 3, 4, and 5. After the pretreatment, 39, 33, and 24% higher methane yield from pine was achieved for F/I ratios of 3, 4, and 5, respectively. However, the methane yield from the hardwoods was not improved by the pretreatment, which was related to overloading of the digester. Compositional analysis showed considerable reduction in hemicellulose and lignin content by the pretreatment. Structural changes in the woods, before and after the pretreatment, were examined by X-ray diffractometer and scanning electron microscopy. The results showed that the crystallinity of cellulose was decreased and accessible surface area was drastically increased by the pretreatment.

  • Researchpp 3244-3258Revin, V., Novokuptsev, N., and Kadimaliev, D. (2016). "Preparation of biocomposites using sawdust and lignosulfonate with a culture liquid of levan producer Azotobacter vinelandii as a bonding agent," BioRes. 11(2), 3244-3258.AbstractArticlePDF

    The possibility of preparing molding-bioengineered materials, such as woodchip boards (WCB), from sawdust using technical lignosulfonate (LGS), a wood waste product, and a culture liquid (CL) of levan microbial polysaccharide producer by Azotobacter vinelandii D-08 is explored in this article. The parameters of the derived materials are comparable to those of traditional materials made from toxic phenol-formaldehyde resins. The various physical and mechanical characteristics of the materials depend on the quantity of the bonding agent used for the preparation. Adding a culture liquid increases the humidity resistance of the molding materials. Using electron microscopy and X-ray micro-tomography, it is clear that the structure of woodchip boards become more homogeneous without microcracks with the addition of CL. The strength of the best samples prepared was approximately 24 to 29 MPa with a density of 1170 to 1255 kg/m3 and a swell on wetting of 6.7%. During hot pressing, noticeable changes were observed by Fourier transform infrared spectroscopy (FTIR) at frequencies typical of LGS sulfonic-acid groups, levan fructose fragments, and skeletal vibrations of a syringal/guaiacyl core in lignin and of C-H groups of hemicelluloses. This indicates the involvement of these functional groups in the process of binding wood particles with hot pressing.

  • Researchpp 3259-3274Li, A., Liu, H. L., Wang, H., Xu, H. B., Jin, L. F., Liu, J. L., and Hu, J. H. (2016). "Effects of temperature and heating rate on the characteristics of molded bio-char," BioRes. 11(2), 3259-3274.AbstractArticlePDF

    A slow pyrolysis of pinewood was investigated in this paper. Through the briquette process, the pinewood sawdust becomes molded biomass. The molded bio-char was produced from molded biomass with different pyrolysis factors, and the bio-char’s heating value, char yield rates, and physicochemical and morphological properties were investigated. Molded bio-char’s characteristics depended principally on pyrolysis factors. At low temperature (400 °C), the char yield rate was positively correlated to the heating rate. But at higher temperatures (500 to 700 °C), the char yield rates decreased as heating rates increased. As pyrolysis temperature increased from 400 to 700 °C, the following increased in molded bio-char: fixed-carbon content, percentage carbon, heating value, ash content, as well as surface areas. And its pore structure, graphite degree, and polymerization degree achieved a higher level. Compared with pulverized bio-char, the molded bio-char had a higher char yield rate, ash content, graphite degree, and structure ordering. The molded bio-char obtained from a low temperature (400 °C) and high heating rate (15 °C/min) can be used as a reducing agent, the molded bio-char from 600 °C is recommend as an activated carbon precursor, and the molded bio-chars from low temperature (400 °C) have a higher efficiency as fuel.

  • Researchpp 3275-3288Nguyen, Q. N., Cloutier, A., Achim, A., and Stevanovic, T. (2016). "Fuel properties of sugar maple and yellow birch wood in relation with tree vigor," BioRes. 11(2), 3275-3288.AbstractArticlePDF

    The fuel properties of wood obtained from sugar maple (SM) and yellow birch (YB) of temperate hardwood stands located in the Province of Québec, Canada were studied to see how tree vigor affects the chemical composition and calorific value of the wood. This study focused on the physical and chemical properties of wood with the aim of using the material for the production of solid biofuels. Specific items measured included the wood’s calorific values, and the levels of extractives, ash, and lignin. Changes in chemical composition were found among tree vigor classes. The low vigor trees had higher extractives, ash, and lignin contents than the vigorous trees. Total extractives ranged between 4.88 and 7.32% in SM, and between 3.35 and 5.12% in YB. Klason lignin ranged between 21.46 and 23.53% in SM, and between 18.60 and 21.51% in YB. Ash content ranged between 0.38 and 0.97% in SM, and between 0.26 and 0.47% in YB. The combined effects of higher lignin content that could contribute to a better self-bonding of particles and of higher extractives content that could facilitate the pelletization process makes the low vigor trees more suitable for conversion into solid biofuels. The higher amounts of extractives and lignin present in the low vigor sugar maple and yellow birch trees could also have a positive role in maintaining the high calorific values of this wood despite higher ash content.

  • Researchpp 3289-3302Dong, A., Fan, X., Wang, Q., Yu, Y., and Cavaco-Paulo, A. (2016). "Enzymatic treatments to improve mechanical properties and surface hydrophobicity of jute fiber membranes," BioRes. 11(2), 3289-3302.AbstractArticlePDF

    Fiber membranes prepared from jute fragments can be valuable, low cost, and renewable. They have broad application prospects in packing bags, geotextiles, filters, and composite reinforcements. Traditionally, chemical adhesives have been used to improve the properties of jute fiber membranes. A series of new laccase, laccase/mediator systems, and multi-enzyme synergisms were attempted. After the laccase treatment of jute fragments, the mechanical properties and surface hydrophobicity of the produced fiber membranes increased because of the cross-coupling of lignins with ether bonds mediated by laccase. The optimum conditions were a buffer pH of 4.5 and an incubation temperature of 60 °C with 0.92 U/mL laccase for 3 h. Laccase/guaiacol and laccase/alkali lignin treatments resulted in remarkable increases in the mechanical properties; in contrast, the laccase/2,2’-azino-bis-(3-ethylthiazoline-6-sulfonate) (ABTS) and laccase/2,6-dimethoxyphenol treatments led to a decrease. The laccase/ guaiacol system was favorable to the surface hydrophobicity of jute fiber membranes. However, the laccase/alkali lignin system had the opposite effect. Xylanase/laccase and cellulase/laccase combined treatments were able to enhance both the mechanical properties and the surface hydrophobicity of jute fiber membranes. Among these, cellulase/laccase treatment performed better; compared to mechanical properties, the surface hydrophobicity of the jute fiber membranes showed only a slight increase after the enzymatic multi-step processes.

  • Researchpp 3303-3317Llana, D. F., Iñiguez-Gonzalez, G., Arriaga, F., and Wang, X. (2016). "Time-of-flight adjustment procedure for acoustic measurements in structural timber," BioRes. 11(2), 3303-3317.AbstractArticlePDF

    The effect of timber length on time-of-flight acoustic longitudinal measurements was investigated on the structural timber of four Spanish species: radiata pine (Pinus radiata D. Don), Scots pine (Pinus sylvestris L.), laricio pine (Pinus nigra Arn.), and maritime pine (Pinus pinaster Ait.). Time-of-flight longitudinal measurements were conducted on 120 specimens of dimensions 90 × 140 mm using three commercially available acoustic instruments (Sylvatest Duo, USLab, and Microsecond Timer). Time-of-flight data were initially obtained from the full-length (4 m) specimens, and then from the specimens cut to 3, 2, and 1 meter in length by successively cutting off 0.5 m from each end. The acoustic longitudinal velocity of the timber specimens of different lengths was also measured using a resonance-based acoustic method. The apparent acoustic longitudinal velocity for all species increased linearly as the timber length decreased from 4 to 1 meter. Acoustic velocity determined from time-of-flight data was significantly higher than the acoustic velocity determined using the resonance method, indicating systematic measurement errors associated with the time-of-flight instruments. Empirical models were developed for the relationships between time-of-flight measurements on timber specimens and timber lengths in the range of 1 to 4 m. Finally, a procedure was proposed to correct the time-of-flight data.

  • Researchpp 3318-3331Song, W., Wei, W., Ren, C., and Zhang, S. (2016). "Developing and evaluating composites based on plantation eucalyptus rotary-cut veneer and high-density polyethylene film as novel building materials," BioRes. 11(2), 3318-3331.AbstractArticlePDF

    To achieve value-added utilizations of plantation timbers, eucalyptus veneer/high-density polyethylene film composites were prepared, with process-factors (PF) (hot-pressing temperature, HT; hot-pressing duration, HD; hot-pressing pressure, HP; HDPE-film content, HC) and composite-properties (CP) (water-resistant bonding-strength, BS; modulus of rupture, MOR; modulus of elasticity, MOE) investigated. According to thermal analyses, 140 to 180 °C was appropriate for HT. Based on statistical analyses, HD was easier to affect CP, while MOE was easier to be affected by PF. Quantitative relationships between PF and CP were determined by the neural-network (ANN) modeling. In ANN simulation surveys, CP displayed Gaussian distributions (R2 > 0.9) when PF changed in current ranges, with positive correlations between BS and MOR (R2 ≈ 0.5). Combining ANN and the genetic-algorithm, optimal processes (HT, 160 °C; HD, 50 s/mm; HP, 1.3 MPa; HC, 6 layers) were found, and optimal results (BS, 1.30 MPa; MOR, 86.94 MPa; MOE, 8.33 GPa) were comparable to various reported poplar-plywoods. Microscopic images demonstrated that composite interfaces were formed by the mechanical interlocking. The optimal BS attained Chinese standards for water-resistant plywoods, so proposed composites can serve as water-resistant and formaldehyde-free building materials for furniture and interior design.

  • Researchpp 3332-3355Birnin-Yauri, A. U., Ibrahim, N. A., Zainuddin, N., Abdan, K., Then, Y. Y., and Chieng, B. W. (2016). "Influence of kenaf core fiber incorporation on the mechanical performance and dimensional stability of oil palm fiber reinforced poly(lactic acid) hybrid biocomposites," BioRes. 11(2), 3332-3355.AbstractArticlePDF

    This study demonstrated the reinforcing potential of kenaf core fiber (KCF) to complement and sustain oil palm fiber supply chain in the production of natural fiber-thermoplastic biocomposites. The lignin-rich KCF was incorporated into cellulose-rich oil palm empty fruit bunch fiber (EFBF)- and oil palm mesocarp fiber (OPMF)-poly(lactic acid) (PLA) composites, aimed at achieving synergism. The hybrid biocomposites developed by melt blending and subsequent compression molding were characterized for possible application as an alternative to medium-density fiberboards. The mechanical properties and dimensional stability of both single fiber- and hybrid fiber-PLA biocomposites were evaluated and compared. The test results showed a synergistic improvement as a consequence of fiber hybridization. Also, the findings suggested the best material performance with the incorporation of 5% KCF into 55% EFBF or OPMF and 40% PLA matrix. The OPMF-KCF-PLA hybrid biocomposites gave better results than the EFBF-KCF-PLA hybrid biocomposites.

  • Researchpp 3356-3372Chowdhury, Z. Z., Karim, M. Z., Ashraf, M. A., and Khalid, K. (2016). "Influence of carbonization temperature on physicochemical properties of biochar derived from slow pyrolysis of durian wood (Durio zibethinus) sawdust," BioRes. 11(2), 3356-3372.AbstractArticlePDF

    The objective of this study was to explore the influence of pyrolysis temperature on the physicochemical properties of biochar synthesized from durian wood (Durio zibethinus) sawdust. Surface morphological features, including the porosity and BET surface area of biochars, provide appropriate dimensions for growing clusters of microorganisms with excellent water retention capacity in soil. Oxygen-containing surface functional groups play a vital role in improving soil fertility by increasing its cation and anion exchange capacities with reduced leaching of nutrients from the soil surface. Biochar was produced via slow pyrolysis of woody biomass (WS) using a fixed bed reactor under an oxygen-free atmosphere at different pyrolysis temperatures (350, 450, and 550 °C). The biochars obtained were characterized using ultimate and proximate analyses, Brunauer-Emmett-Teller (BET) surface area, field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The yield of biochar decreased from 66.46 to 24.56%, whereas the BET surface area increased sharply from 2.567 to 220.989 m2/g, when the pyrolysis temperature was increased from 350 to 550 °C. The results highlighted the effect of pyrolysis temperature on the structure of the biochar, which could be advantageous for agricultural industries.

  • Researchpp 3373-3383Ståhl, M., Berghel, J., and Granström, K. (2016). "Improvement of wood fuel pellet quality using sustainable sugar additives," BioRes. 11(2), 3373-3383.AbstractArticlePDF

    The global production and use of wood fuel pellets has increased significantly in recent years. The raw material and the energy required to dry it are the main production costs. Therefore, it is crucial to minimize energy consumption, production costs, and the environmental impact associated with wood pellets. However, these changes should not negatively affect the quality of the pellets. One way to achieve these goals is to use additives. This work investigates how different types of sugar additives affect both the energy needed by the pellet press and the durability and oxidation of the produced pellets. When sugar was used as an additive, the energy use was practically unaffected. When molasses and SSL were added, a small decrease in energy use was observed (6 to 8%) for admixtures up to 1 wt.%; however, when more molasses was added, the energy use increased. Using these additives increased the bulk density (7 to 15 %) and durability (10 to 20 %) of the pellets. The storage of the pellets also caused a small increase in durability (1 to 3 %). Volatile organic compounds were produced as oxidation peaks within the first two months of storage; thereafter, the peaks tapered off.

  • Researchpp 3384-3396Li, M., Ma, S., and Zhu, X. (2016). "Preparation of activated carbon from pyrolyzed rice husk by leaching out ash content after CO2 activation," BioRes. 11(2), 3384-3396.AbstractArticlePDF

    To prepare activated carbons with a high porosity and low ash content from pyrolyzed rice husk, the method of KOH or K2CO3 solution leaching after CO2 activation was investigated. The effects of KOH or K2CO3 concentration and leaching time on the yield, ash content, and textural properties of the activated carbon were studied, and the activated carbon prepared under the best conditions was characterized. The results showed that the best leaching time was 1 h for KOH and K2CO3, and the best concentrations were 1.0 and 4.0 M, respectively. The leaching process was greatly beneficial to the development of the pore structure. The specific surface area of the activated carbon prepared under the most favorable conditions was approximately 1100 m2/g, and the iodine values were greater than 1100 mg/g. As a result of the leaching process, the ash content of the sample was notably decreased from 63% to approximately 5%, andthe porosity development was attributed to the reaction of the leaching reagents with silica.

  • Researchpp 3397-3415Chowdhury, Z. Z., and Hamid, S. B. A. (2016). "Preparation and characterization of nanocrystalline cellulose using ultrasonication combined with a microwave-assisted pretreatment process," BioRes. 11(2), 3397-3415.AbstractArticlePDF

    This study focuses on the extraction of nanocrystalline cellulose (NCC) from the dried stalk of Corchorus olitorius,commonly known as jute,using a combination of a microwave-assisted alkaline peroxide pulping process (AHP) and ultrasonication. Dried jute stalk powder was pretreated using sodium hydroxide under microwave irradiation for the removal of lignin. The partially delignified sample was bleached using 30% hydrogen peroxide solution. The resulting crude cellulose was hydrolyzed using ultrasonication in the presence of ionic liquid and sulfuric acid. The effect of hydrolyzing medium on the physicochemical characteristics of the extracted nanocellulose was investigated. The nanocrystalline cellulose (NCC) obtained after combined treatments was rod-like, with diameters of 10 to 15 nm and lengths of 92 to 105 nm. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD) showed that some breakages of intramolecular hydrogen bonds and glycosidic bonds occurred during the hydrolysis reaction of pretreated biomass. Ultrasonication in the presence of an acid hydrolyzing medium most effectively accelerated these breakages in the long chain cellulose biopolymer, leading to the formation of nanocrystalline cellulose (NCC) with higher crystallinity.

  • Researchpp 3416-3431Balea, A., Merayo, N., Fuente, E., Delgado-Aguilar, M., Mutje, P., Blanco, A., and Negro, C. (2016). "Valorization of corn stalk by the production of cellulose nanofibers to improve recycled paper properties," BioRes. 11(2), 3416-3431.AbstractArticlePDF

    Corn stalk, an agricultural waste, was valorized by the production of cellulose nanofibers (CNF), which were tested for improving recycled paper properties. CNF from eucalyptus kraft pulp (E-CNF) was used as a reference. Addition of 0.5% wt. CNF produced from corn organosolv pulp (C-CNF) to recycled paper increased the tensile index by 20%, whereas the same improvement with E-CNF was achieved at 1.5% wt. Tensile index was further enhanced by increasing the E-CNF, whereas C-CNF achieved its maximum effect at this dose. Different recycled furnish compositions were studied to evaluate C-CNF as a product additive. C-CNF improved tensile strength in all the different recycled furnishes studied. The tensile index improvement caused by C-CNF did not depend on the proportions of old newspaper and old magazine paper used. Addition of C-CNF to recycled corrugated board fluting increased the tensile strength, but to a slightly lower extent than in the case of recycled newsprint paper.

  • Researchpp 3432-3441Qian, L., Chen, P., Li, R., Mei, L., Liu, Y., Wu, G., and Liu, S. (2016). "Biomorphic charcoal/TiO2 composites from poplar templates," BioRes. 11(2), 3432-3441.AbstractArticlePDF

    Biomorphic charcoal/TiO2 composites (C/TiO2) were produced from poplar templates. The poplar templates were impregnated with butyl titanate sol with a vacuum/positive pressure technology. From the anatomic structure of poplar and fluid thermodynamics, the alternative vacuum/positive pressure technology was an efficient method of infiltrating bio-templates with sol and overcoming the embolization effect of the sol in capillaries. After sol infiltration, the maximum density of the poplar was approximately 0.958 ± 0.005 g/cm3. Using X-ray diffraction (XRD), thermogravimetric data (TG-DTG), and scanning electron microscopy (SEM), it was found that the pore sizes in the cell walls of C/TiO2 were, respectively, 30 to 150, 3 to 15, and 1.5 μm, and a surprising mesoporous-like honeycomb structure formed at approximately 800 °C in a N2 atmosphere. The phase structure of C/TiO2 shifted from anatase to rutile between 700 and 900 °C in N2. Furthermore, the temperature of the maximum combustion rates of C/TiO2 sintered at 800 °C in N2 was approximately 610 °C. The average shrinkage values from the native poplar to C/TiO2 along the radial, tangential, and axial directions were 28.53%, 21.80%, and 17.03%, respectively.

  • Researchpp 3442-3452Kačík, F., Luptáková, J., Šmíra, P., Nasswettrová, A., Kačíková, D., and Vacek, V. (2016). "Chemical alterations of pine wood lignin during heat sterilization," BioRes. 11(2), 3442-3452.AbstractArticlePDF

    This study investigated alterations in the lignin of pinewood (Pinus sylvestris L.) during heat sterilization. The Klason lignin content was determined, and the dioxane lignin was isolated. Changes in the dioxane lignin were evaluated by size exclusion chromatography (SEC) as well as Fourier transform infrared (FTIR) spectroscopy. The analyses illustrated an increase in the percentage of extractives and the amount of dioxane lignin yields, while a decrease in the acid-insoluble lignin content was also observed. Changes in the macromolecular characteristics of the dioxane lignin (molecular weight and polydispersity) were not significant (p < 0.05); however, they indicated that simultaneous degradation and condensation reactions had occurred. The FTIR spectra of the dioxane lignins showed an increase at 3420 cm-1 (O-H stretching vibration), indicating the cleavage of ether bonds. The band at 1715 cm-1 (unconjugated C=O stretching) increased after an initial decrease due to the cleavage of the β-alkyl-aryl ether bonds. Also, the band at 1660 cm-1 (conjugated C=O groups) increased, which was caused by the cleavage of the α-alkyl-aryl ether bonds.

  • Researchpp 3453-3465Owi, W. T., Lin, O. H., Sam, S. T., Chia, C. H., Zakaria, S., Mohaiyiddin, M. S., Villagracia, A. R., Santos, G. N., and Md Akil, H. (2016). "Comparative study of microcelluloses isolated from two different biomasses with commercial cellulose," BioRes. 11(2), 3453-3465.AbstractArticlePDF

    Microcelluloses (MCs) were chemically isolated from two different biomass sources, empty fruit bunches (EFB) and sugarcane bagasse (SCB). The resulting MCs were compared to the commercially available cellulose (MC-Sigma) that was used as a standard. Structural, crystalline, morphological, and thermal properties of all specimens were characterized and compared by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). FTIR analysis verified that the chemical treatments removed non-cellulosic constituents including hemicelluloses and lignin. XRD patterns revealed the crystallinity increment from 43.1% to 52.1% for MC-EFB and 38.9% to 52.4% for MC-SCB. SEM images demonstrated the fibrillar structure of both MC-EFB and MC-SCB, and their surfaces were smoother compared with MC-Sigma. From the TG curves, MC-EFB provided the highest thermal stability, as it had the highest maximum degradation temperature at 345 °C. DSC results showed only one endothermic peak for all specimens. Taken together, these results reasonably confirmed that the MCs from EFB and SCB are comparable to standard MC-Sigma.

  • Researchpp 3466-3480Mahmood Raouf, R., Abdul Wahab, Z., Azowa Ibrahim, N., Abidin Talib, Z., and Chieng, B. W. (2016). "Miscible transparent polymethylmethacrylate/cellulose acetate propionate blend: Optical, morphological, and thermomechanical properties," BioRes. 11(2), 3466-3480.AbstractArticlePDF

    To obtain a high transmittance blend within ultraviolet and visible regions, various transparent samples of ascending percentages of polymethylmethacrylate (PMMA)/cellulose acetate propionate (CAP) were prepared by melt blending using a twin screw extruder. These blends were characterised by ultraviolet-visible spectroscopy, and the curves illustrated that the blending ratio of 10% CAP in PMMA meets the required purpose. The morphological, mechanical, and thermal properties for pure PMMA and the PMMA/CAP 10% blend were investigated using X-ray diffraction, scanning electron microscopy, dynamic mechanical analysis, and thermogravimetric analysis. The results showed that the PMMA/CAP 10% blend has an amorphous structure and low stiffness than pure PMMA. The miscible PMMA/CAP 10% blend exhibited mechanical stability below the glass transition temperature (Tg), with a slight increase in Tg value relative to that of pure PMMA. The study also demonstrated that the intermolecular interaction between blend elements has an effective influence on the physical properties of the blend.

  • Researchpp 3481-3493Sha, J., Zhang, F., and Zhang, H. (2016). "Thixotropic flow behaviour in chemical pulp fibre suspensions," BioRes. 11(2), 3481-3493.AbstractArticlePDF

    This paper presents results on the thixotropic behaviour of hardwood and softwood pulp fibre suspensions. Three rheological tests including hysteresis-loops, creep tests, and step-wise experiments were used to investigate the thixotropic rheology. Both suspensions exhibited a plateau in their flow curves where a slight change of the applied shear stress led to a dramatic change in the corresponding shear rates. During creep experiments under controlled stress, they evolved either towards a rapid shear (liquid regime) or stoppage (solid regime), depending on the relative values of the imposed stress, leading to a viscosity bifurcation around a critical stress. The transient response of pulp to step changes in shear rate was marked by a characteristic time, which can be used to understand the rate of structural change for pulp suspensions. Moreover, the yielding and thixotropic behaviour of the pulp suspensions were highly dependent on shear history and the time of rest prior to the measurement.

  • Researchpp 3494-3510Giummarella, N., Lindgren, C., Lindström, M. E., and Henriksson, G. (2016). "Lignin prepared by ultrafiltration of black liquor: Investigation of solubility, viscosity, and ash content," BioRes. 11(2), 3494-3510.AbstractArticlePDF

    Technical lignin, which can be potentially obtained in large amounts as a by-product from kraft pulping, represents a potential resource for manufacturing fuels and chemicals. Upgrading of lignin, by lowering its molecular weight, is a valuable alternative to precipitation from black liquor, which occurs in the Lignoboost process. The solubility properties of Lignoboost lignin and filtered lignin in a number of technically feasible solvents were compared, and it was found that both lignins were dissolved in similar solvents. With the exception of furfural, the best lignin solvents generally were organic solvents miscible with water, such as methanol. It was possible to dissolve more filtered lignin in higher concentrations than Lignoboost lignin; additionally, the viscosities of the filtered lignin solutions were also considerably lower than those of Lignoboost lignin, especially at higher concentrations. Methods for non-organic component removal from filtrated lignin were tested, and it was concluded that several cold acidic treatments after dewatering can lower the ash content to values below 0.5% by weight.

  • Researchpp 3511-3523Yuan, Z., Long, J., Xia, Y., Zhang, X., Wang, T., and Ma, L. (2016). "Production of levulinic acid from Pennisetum alopecuroides in the presence of an acid catalyst," BioRes. 11(2), 3511-3523.AbstractArticlePDF

    The perennial grass Pennisetum alopecuroides was degraded using a conventional heating method with sulfuric acid. The effects of temperature (150 to 200 °C), reaction time (30 to 210 min), acid concentration (2% to 10%), and solid-liquid ratio (1:10 to 1:4) were optimized for P. alopecuroides hydrolysis. The production of levulinic acid was strongly affected by variations in these parameters. The optimum conditions with respect to reaction temperature, time, acid concentration, and solid-liquid ratio were 190 °C, 60 min, 8%, and 1:6, respectively. The maximum levulinic acid yield using the optimum conditions was 50.49%. The residues obtained from various temperatures were also intensively characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric (TG) analyses. These results extend the current understanding of the bioconversion and utilization of renewable lignocellulosic biomass.

  • Researchpp 3524-3537Zaaba, N. F., Ismail, H., and Jaafar, M. (2016). "Recycled polypropylene/peanut shell powder composites: Pre-treatment of lignin using alkaline peroxide," BioRes. 11(2), 3524-3537.AbstractArticlePDF

    This study investigated the performance of recycled polypropylene (RPP)/peanut shell powder (PSP) composites with untreated PSP and treated PSP with alkaline peroxide. The RPP/PSP and RPP/PSP-H2O2 composites were prepared by melt mixing and compression molding at different PSP loadings (10 wt.% to 40 wt.%). The samples were characterized by processing properties, tensile properties, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and water absorption behavior. The treated PSP enhanced the stabilization torque, tensile strength, elongation at break, tensile modulus, and water absorption of RPP/PSP-H2O2 composites. FTIR spectra and SEM showed that the elimination of lignin content strongly influenced the fractured surface and chemical characteristics of the RPP/PSP-H2O2 composites.

  • Researchpp 3538-3549Han, Y., Ta, J., and Qi, D. (2016). "Computer tomography of the density and its spatial distribution of wood-plastic composites," BioRes. 11(2), 3538-3549.AbstractArticlePDF

    The density and its spatial distribution of wood-plastic composites (WPCs) were tested by the computer tomography (CT) method. Based on the correlation among the attenuation coefficient, density, and CT number, a mathematical model between CT number and density of WPCs was established. This contributed to the realization of fast and nondestructive detection of WPC density and to the determination of the quality of wood-plastic composite products. Taking pine and poplar wood powder WPCs as subjects, the density was higher near the edge and lower in the middle of the sample, which resembled a “V” shape in the width direction. Compared with the density variations of poplar wood powder WPCs, those of pine wood powder had more of a “V” distribution.

  • Researchpp 3550-3560Xue, L., Zhao, Z., Zhang, Y., Chu, D., and Mu, J. (2016). "Analysis of gas chromatography-mass spectrometry coupled with dynamic headspace sampling on volatile organic compounds of heat-treated poplar at high temperatures," BioRes. 11(2), 3550-3560.AbstractArticlePDF

    Thermal modifications tend to darken wood color and enhance dimensional stability, erosion resistance, weather resistance, and product value. To investigate the chemical characteristics of VOCs influenced by the heat treatment process, air-dried poplar wood was heat-treated at four treatment temperatures (160,180, 200, and 220 °C) for 2 h. Near-infrared spectroscopy (NIR) was used to investigate the changes in sample hemicellulose, cellulose, and lignin composition. Acid-insoluble lignin and holocellulose were determined using wet chemistry methods. Volatile organic compounds of the poplar wood were analyzed for composition using gas chromatographic-mass spectroscopy coupled with dynamic headspace sampling. The results showed that the most significant volatiles in heat-treated poplar were aldehydes, which were the most abundant compound at 180 °C, in the furfural form. The amount of aromatic compounds and esters increased with increasing temperature. In addition, alcohol benzene extractives and acid-insoluble lignin increased, while holocellulose content decreased.

  • Researchpp 3561-3574Darmawan, S., Wistara, N. J., Pari, G., Maddu, A., and Syafii, W. (2016). "Characterization of lignocellulosic biomass as raw material for the production of porous carbon-based materials," BioRes. 11(2), 3561-3574.AbstractArticlePDF

    Lignocellulosic biomass is a potential raw material that can be used in the synthesis (manufacture) of porous carbon stuffs. The properties of such porous carbon products are affected by the species of the raw material and the manufacturing process, among other things. This paper scrutinizes the related characteristics of lignocellulosic raw materials that indicate potential for the production of porous carbon. Three species were used: pine (Pinusmerkusii) wood, mangium (Acacia mangium) wood, and candlenut (Aleuritesmoluccana) shells, representing softwoods, hardwoods, and non-wood stuffs, respectively. Analyses of their chemical compounds and proximate contents were carried out. Additionally, nano scale scrutiny of the lignocellulosic biomass was also conducted using the nano capable instruments, which consisted of SEM, EDS, XRD, FTIR, and DSC. Results revealed that pine wood had the most potential to produce porous carbon. Morphologically, pine wood afforded the best permeability, whereby at the structure of monoclinic cellulose crystals, there were cellulose-Ia structures, which contained less cellulose-Ib structures. Furthermore, pine wood exhibited greater volatile matter content, as confirmed through the FTIR, which greatly assisted the forming of porosity inside its corresponding carbon.

  • Researchpp 3575-3586Salman, S. D., Sharba, M. J., Leman, Z., Sultan, M. T. H., Ishak, M. R., and Cardona, F. (2016). "Tension-compression fatigue behavior of plain woven kenaf/kevlar hybrid composites," BioRes. 11(2), 3575-3586.AbstractArticlePDF

    The applications of hybrid natural/synthetic reinforced polymer composites have been rapidly gaining market share in structural applications due to their remarkable characteristics and the fact that most of the components made of these materials are subjected to cyclic loading. Their fatigue properties have received a lot of attention because predicting their behavior is a challenge due to the effects of the synergies between the fibers. The purpose of this work is to characterize the tension, compression, and tensile-compression fatigue behavior of six layers of Kevlar hybridized with one layer of woven kenaf reinforced epoxy, at a 35% weight fraction. Fatigue tests were carried out and loaded cyclically at 60%, 70%, 80%, and 90% of their ultimate compressive stress. The results give a complete description for tensile and compression properties and could be used to predict fatigue-induced failure mechanisms.

  • Researchpp 3587-3597Villasante, A., Fernandez-Serrano, A., Puigdomenech, L., Lampurlanes, J., and Moliner, D. (2016). "Effect of a longitudinal cut on the mechanical properties of small-diameter roundwood of Pinus nigra Arnold," BioRes. 11(2), 3587-3597.AbstractArticlePDF

    The use of roundwood in structures has drawbacks that include tapering and lack of flatness, which can be overcome by making a longitudinal cut to flatten one side. The aim of this work was to compare the mechanical behavior of roundwood vs. roundwood with one flat face, comparing pieces of small-diameter roundwood from young trees of Pinus nigra Arnold. Half the samples were given a longitudinal cut. Specimens taken from these pieces were tested for bending and compression parallel to the grain to determine their modulus of elasticity and strength. The modulus of rupture by bending was 22% lower in roundwood with one flat face (59.0 MPa) than in roundwood (75.6 MPa). It has been observed that the smaller cross section in the roundwood with one flat face is not the only explanation for the decrease in the bending strength. In contrast, no significant differences were observed for the other three mechanical properties studied (compression strength parallel to the grain and modulus of elasticity in bending and compression).

  • Researchpp 3598-3613Zhang, X., Li, J., Liu, H., and Zhou, P. (2016). "Soft sensors for pulp freeness and outlet consistency estimation in the alkaline peroxide mechanical pulping (APMP) high-consistency refining process," BioRes. 11(2), 3598-3613.AbstractArticlePDF

    In the mechanical pulping process, some process state and product quality variables are difficult to measure on-line. In this paper, soft sensors were used to estimate Canadian Standard Freeness (CSF) and outlet consistency (Cout) after the high consistency refining stage of the alkaline peroxide mechanical pulping (APMP) process. After the secondary variables for modeling that are readily available processed measurements in pre-treatment and the HC refining stage was selected, models based on the case-based reasoning (CBR) method were developed to estimate CSF and Cout. The ability of CBR soft sensors to predict CSF and Cout was tested using data collected from an APMP mill, and the results were satisfactory. Additionally, two typical soft sensor methods that back propagation network (BP) algorithms and support vector regression algorithms (SVR) were employed to predict CSF and Cout and evaluate the performance of the CBR soft sensor. As a result, the proposed soft sensor demonstrated a better performance than the BP method and can be regarded as of comparable quality to the SVR method.

  • Researchpp 3614-3625Li, W., Ren, D., Zhang, X., Wang, H., and Yu, Y. (2016). "The furfurylation of wood: A nanomechanical study of modified wood cells," BioRes. 11(2), 3614-3625.AbstractArticlePDF

    Furfurylation of wood is of interest worldwide as an environmentally friendly modification process. It is widely assumed that low-molecular weight furfuryl alcohol (FA) can penetrate into wood cells and polymerize in-situ during the process, resulting in substantial improvement in the physical-mechanical properties and durability of wood. In this study, confocal laser scanning microscopy (CLSM) was used to visualize the microscopic distribution of polymerized FA resin in the Masson pine wood cavities, and a Nanoindenter was used to probe the mechanical properties of modified wood cells. The effects of catalysts (maleic anhydride and a mixed organic acid catalyst), FA concentration, curing time, and curing temperature on the nanomechanical properties of wood cell walls were investigated. An improvement in the indentation modulus and hardness of modified wood cells demonstrated indirectly but strongly that FA indeed penetrated wood cells during the modification process. Based on the results of the cell wall nanoindentation test, a combination of 50% furfuryl alcohol, 8 h curing time, and 95 °C curing temperature were proposed as the starting processing parameters for the development of a more practical and effective wood furfurylation process using a mixed organic acid catalyst.

  • Researchpp 3626-3636Liu, C., Deng, Y., Wu, S., Lei, M., and Liang, J. (2016). "Experimental and theoretical analysis of the pyrolysis mechanism of a dimeric lignin model compound with α-O-4 linkage," BioRes. 11(2), 3626-3636.AbstractArticlePDF

    Tar and char can be regarded as unwanted byproducts during the gasification process. In this study, three types of catalyst, i.e., biomass char (bio-char), nickel supported on biomass (Ni+bio-char), and nickel supported on bio-char (bio-char+Ni), were studied to compare the catalytic effects of different preparation methods on tar model compound removal. The structural characteristics of the three catalysts were also investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) methods. The results revealed that Ni+bio-char catalyst showed much higher activity for the reformation of toluene (C7H8) as a tar model compound than the other two catalysts. Toluene could be completely converted to small gas molecules at a conversion rate of 99.92% at 800 °C, and the maximum yield of gas was 432 mL/(mL C7H8). In particular, the H2 and CH4 yields were 339 and 85 mL/(mL C7H8) at 850 °C, respectively. An N2 absorption-desorption experiment demonstrated that the specific surface area of Ni+bio-char was 32.87 times that of bio-char and 8.39 times that of bio-char+Ni. Moreover, metallic nickel (Ni0) particles could be generated in the carbon matrix of Ni+bio-char catalyst. SEM analysis confirmed that the Ni+bio-char catalyst had a more porous structure. Nickel supported on biomass might be a promising catalyst for tar reformation because of its excellent catalytic activities.

  • Researchpp 3637-3659Chowdhury, Z. Z., Yehye, W. A., Julkapli, N. M., Al Saadi, M. A. H., and Atieh, M. A. (2016). "Application of graphitic bio-carbon using two-level factorial design for microwave-assisted carbonization," BioRes. 11(2), 3637-3659.AbstractArticlePDF

    A novel intermittent microwave-assisted carbonization method was developed to prepare bio-char (BWSC) from Durian wood sawdust (BWS). The BWS was further activated using a base-catalytic approach to produce a graphitic form of bio-carbon (BWSAC). A three factor, two-level central composite (CCD) experimental design was used to maximize Pb(II) ion removal from aqueous solution using BWSAC. Three independent variables (initial pH of solution (pH0) ranging from 2 to 8, initial metal ion concentration of Pb(II) cations (C0) ranging from 50 to 100 mg/L, and contact time (Ct) ranging from 10 to 300 min) were consecutively coded as x1, x2, and x3 at three levels (−1, 0 and 1) of the design matrix. The experimental conditions in terms of actual factors were determined to be x1 (pH0) = 5.86, x2 (C0) = 57.77 mg/L, and x3 (temperature) = 53.85 °C, and the resultant Pb(II) ion removal efficiency (y1) obtained was 92.73%, with a model desirability of 0.974. The change in physiochemical properties after carbonization as well as activation was observed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer, Emmett and Teller surface area analysis (BET), Thermogravimetric analysis (TGA), Ultimate analysis, and Fourier transform infrared spectroscopy (FTIR).

  • Researchpp 3660-3678Zhang, X., Li, J., and Liu, H. (2016). "Improved model for brightness optimization control in the first (C95/D5) bleaching stage," BioRes. 11(2), 3660-3678.AbstractArticlePDF

    In the first stage of pulp bleaching, the quantity of added chemicals (ClO2 and/or Cl2) is commonly controlled by kappa factor, based on a kappa number online analyzer together with a compensated brightness control scheme as a feedback strategy. However, a kappa number analyzer is not always available, so the bleaching quality relies heavily on the chemical dosage set-point chosen by the operators. In this study, an improved model for the chlorination stage brightness optimization was proposed, based on brightness and residual chemicals before pulp enters the bleaching tower. Additionally, the experience of operators of (C95/D5) bleaching was employed in order to find an optimum chemical dosage set-point quickly. The golden section search algorithm (i.e., ‘0.618 method’) was used to find the optimum chemical dosage in this paper. After applying the proposed method in a pulp mill (C95/D5) bleaching stage, the chlorination stage brightness shifted from 62.9% ISO to the target value 60.7% ISO. Meanwhile, the standard deviation was reduced from 3.0 to 2.5.

  • Researchpp 3679-3690Dong, Y., Qin, Y., Wang, K., Yan, Y., Zhang, S., Li, J., and Zhang, S. (2016). "Assessment of the performance of furfurylated wood and acetylated wood: Comparison among four fast-growing wood species," BioRes. 11(2), 3679-3690.AbstractArticlePDF

    Four fast-growing wood species were treated, including two hardwood species and two softwood species, with either furfurylation or acetylation for comparison and analysis. The properties of the resultant woods, including weight percent gain, bulking effect, leach rate, anti-swelling efficiency (ASE), and color changes, were compared comprehensively. The effects of wood species on modification efficiency were also evaluated by morphological analysis. The results indicated that the species of wood had little effect on successful acetylation, but that wood species with more open pits and loose and ordered structures were best suited for furfurylation. Both types of modification resulted in wood samples with more uniform colors than untreated samples. Furfurylation caused considerable color changes in all of the wood samples; acetylation resulted in wood samples slightly lighter in color (lower ΔE* values). The differences in ΔE* values among the four wood species were primarily due to the natural differences in the color of the woods.

  • Researchpp 3691-3708Khandanlou, R., Ngoh, G. C., Chong, W. T., Bayat, S., and Saki, E. (2016). "Fabrication of silver nanoparticles supported on the rice straw: In vitro antibacterial activity and its heterogeneous catalysis in the degradation of 4-nitrophenol," BioRes. 11(2), 3691-3708.AbstractArticlePDF

    To investigate the influence of pH on the size and distribution of silver nanoparticles (Ag-NPs) as well as the antibacterial activity and catalytic performance of rice straw/silver nanocomposites (RS/Ag-NCs), Ag-NPs were synthesized on the surface of rice straw (RS) with various percentages of Ag-NPs (1.0, 5.0, 10.0, and 20.0 wt.%) under different temperatures and diverse pH values. The ultraviolet-visible spectroscopy of synthesized RS/Ag-NCs became noticeable with increased pH, and the peaks were blue-shifted to lower wavelengths. X-ray powder diffraction (PXRD) demonstrated the presence of pure Ag-NPs. Transmission electron microscopy (TEM) showed that the diameters of Ag-NPs on RS were between 7.78 and 2.84 nm at pH values of 8 to 10. The antibacterial activity of various sizes of Ag-NPs on RS was examined using Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) based on the well diffusion technique. Higher antibacterial activity was detected as the loading percentage of RS/Ag-NCs increased and particle size decreased. The superior catalytic performance of 20.0 wt.% RS/Ag-NCs was considered in a test reaction in 4-nitrophenol (4-NP) reduction in the presence of sodium borohydride (NaBH4) in an eco-friendly solvent at ambient temperature. The results represented the high-performance catalytic activity of 20.0 wt.% RS/Ag-NCs.

  • Researchpp 3709-3718Zhu, Y., Jin, E., Yang, F., Li, X., Zhu, W., Yao, C., and Song, J. (2016). "Molecular weight of amphoteric polyacrylamide: How it is influenced by the variables in synthesis, and its impacts on the dry strength of paper sheets," BioRes. 11(2), 3709-3718.AbstractArticlePDF

    Amphoteric polyacrylamide (AmPAM) is a linear water-soluble polymer that has been applied in papermaking as an agent for flocculation, retention, filtration, and dry-strength improvement. However, AmPAM with different ranges of molecular weight (MW) have different properties in these processes. In this study, a series of AmPAMs were constructed with an anionic monomer, itaconic acid (IA), a cationic monomer, methacryloxyethyl-trimethyl ammonium chloride (DMC), and a main backbone of acrylamide (AM). Four factors influencing free radical polymerization, i.e., reaction temperature, pH, initiator load, and the concentration of monomers, were systematically investigated via an orthogonal test to determine their effects on the MW of AmPAM. Spectroscopy and isoelectric point assays were used to characterize the structure of the produced AmPAM, and the MW was assessed by calculating the viscosity. The reaction temperature had the greatest influence on the MW of AmPAM, followed by the solution pH and the initiator load. To determine the dry strength of papersheets containing AmPAM, the breaking length of handsheets was assessed after adding 0.5% AmPAM (based on fiber) with different MWs. The maximum value, 4.05 km, was 15.0% higher than the control and was obtained using AmPAM with a MW of 330 kDa.

  • Researchpp 3719-3735Pech-Cohuo, S. C., Flores-Cerón, I., Valadez-González, A., Cupul-Manzano, C. V., Navarro-Arzate, F., Cruz-Estrada, R. H. (2016). "Interfacial shear strength evaluation of pinewood residue/high-density polyethylene composites exposed to UV radiation and moisture absorption-desorption cycles," BioRes. 11(2), 3719-3735.AbstractArticlePDF

    In outdoor applications, the mechanical performance of wood-plastic composites (WPCs) is affected by UV radiation, facilitating moisture intake and damaging the wood-polymer interfacial region. The purpose of this study was to evaluate the effect of moisture absorption-desorption cycles (MADCs), and the exposure to UV radiation on the interfacial shear strength (IFSS) of WPCs with 40% pinewood residue and 60% high-density polyethylene. One of the WPCs incorporated 5% coupling agent (CA) with respect to wood content. The IFSS was evaluated following the Iosipescu test method. The specimens were exposed to UV radiation using an accelerated weathering test device and subsequently subjected to four MADCs. Characterization was also performed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The absorption and desorption of moisture was slower in non-UV-irradiated WPCs, particularly in those with the CA. The UV radiation did not significantly contribute to the loss of the IFSS. Statistically, the CA had a favorable effect on the IFSS. Exposure of the samples to MADCs contributed to reduce the IFSS. The FTIR showed lignin degradation and the occurrence of hydrolysis reactions after exposure to MADCs. SEM confirmed that UV radiation did not significantly affect the IFSS.

  • Researchpp 3736-3751Oluoti, K., and Richards, T. (2016). "Investigation of the reaction behavior of Albizia gummifera wood under steam gasification with varied partial pressures and gasification temperatures," BioRes. 11(2), 3736-3751.AbstractArticlePDF

    The astronomical increase in global energy demand makes locating energy sources other than fossil fuels worthwhile. The use of tropical biomass wood waste as a renewable energy source was investigated in this study. The thermal conversion analysis of Albizia gummifera (ayinre) was carried out in a thermobalance reactor via steam gasification under varying temperature (700 to 1000 °C) and steam partial pressure (0.020 to 0.050 MPa). The experimental data was evaluated using three gas-solid reaction models. The modified volume reaction model (mVRM) gave the overall highest coefficient of determination (0.9993) and thereby the best conversion prediction. The observed char activation constant rates (from paired reaction conditions) indicated, on average, an increase in reactivity as the parameters increased. The results showed that the activation energy of the mVRM gave the lowest value (32.54 kJ/mol) compared with those of the shrinking core model (SCM) and the volume reaction model (VRM) (49.29 and 49.89 kJ/mol, respectively).

  • Researchpp 3752-3768Liu, J., He, Y., Ma, X., Liu, G., Yao, Y., Liu, H., Chen, H., Huang, Y., Chen, C., and Wang, W. (2016). "Catalytic pyrolysis of tar model compound with various bio-char catalysts to recycle char from biomass pyrolysis," BioRes. 11(2), 3752-3768.AbstractArticlePDF

    Tar and char can be regarded as unwanted byproducts during the gasification process. In this study, three types of catalyst, i.e., biomass char (bio-char), nickel supported on biomass (Ni+bio-char), and nickel supported on bio-char (bio-char+Ni), were studied to compare the catalytic effects of different preparation methods on tar model compound removal. The structural characteristics of the three catalysts were also investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) methods. The results revealed that Ni+bio-char catalyst showed much higher activity for the reformation of toluene (C7H8) as a tar model compound than the other two catalysts. Toluene could be completely converted to small gas molecules at a conversion rate of 99.92% at 800 °C, and the maximum yield of gas was 432 mL/(mL C7H8). In particular, the H2 and CH4 yields were 339 and 85 mL/(mL C7H8) at 850 °C, respectively. An N2 absorption-desorption experiment demonstrated that the specific surface area of Ni+bio-char was 32.87 times that of bio-char and 8.39 times that of bio-char+Ni. Moreover, metallic nickel (Ni0) particles could be generated in the carbon matrix of Ni+bio-char catalyst. SEM analysis confirmed that the Ni+bio-char catalyst had a more porous structure. Nickel supported on biomass might be a promising catalyst for tar reformation because of its excellent catalytic activities.

  • Researchpp 3769-3782Choi, K. H., Kim, A. R., and Cho, B. U. (2016). "Effects of alkali swelling and beating treatments on properties of kraft pulp fibers," BioRes. 11(2), 3769-3782.AbstractArticlePDF

    Three alkali swelling methods were used to treat two kinds of kraft pulp fibers. The morphological and chemical properties of the treated fibers were elucidated in terms of alkali concentration, with the aim of developing bulky paper and conserving wood resources. The effects of beating before and after alkali swelling were examined. The water retention value of fibers increased when higher concentrations of NaOH were used for swelling. Alkali swelling increased fiber width, while fiber length decreased. With increasing NaOH concentration, fibers became curled or kinked; the crystalline structure changed from cellulose I to cellulose II, and the crystalline index decreased. Beating before and after the alkali swelling affected the swelling behavior of kraft pulps, but there was no distinct influence on the crystalline structure. The beating treatment before alkali swelling improved the alkali swelling of fiber. However, beating after the alkali treatment diminished the alkali swelling effects. In addition, the beating after alkali swelling straightened the curled fibers.

  • Researchpp 3783-3798Yao, X., Xu, K., and Li, Y. (2016). "Physicochemical properties and possible applications of waste corncob fly ash from biomass gasification industries of China," BioRes. 11(2), 3783-3798.AbstractArticlePDF

    As a by-product generated from the processing of corn, the production in China of corncob (CC) is abundant, with up to 3.87 million tons per year. The biomass gasification industries make use of the CC residue as feedstock, but large volumes of generated corncob ash (CCA) requires daily disposal. In this study, CCA was characterized by laser particle size analyzer (LPSA), X-ray fluorescence (XRF), X-ray diffraction (XRD), thermal gravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy, and energy dispersive X-ray (SEM-EDX). XRF results showed that the CCA was rich in K, Ca, and P, indicating its potential as a soil amendment. High content of SiO2 in CCA revealed its potential as a pozzolan in blended cement concrete. XRD showed the presence of crystal phases such as potassium carbonate, sylvite, arcanite, quartz, calcite, and nitrite. SEM images revealed the high agglomeration of CCA. EDX gave evidence of the external surface of agglomerated particles coated with KCl. TG-DTA analysis indicates that decomposition of CCA has stepwise mechanism. The CCA powders through a 0.154 mm sieve showed a high specific surface area of 162.32 m2/g, average pore size of 12.17 Å with pore volume of 0.116 cm3/g. The carbon residue separated from CCA has the potential to be used as activated carbon.

  • Researchpp 3799-3812Hassan, N., and Idris, A. (2016). "Simultaneous saccharification and fermentation of lactic acid from empty fruit bunch at high solids loading," BioRes. 11(2), 3799-3812.AbstractArticlePDF

    The production of value-added chemicals from the bioconversion of lignocellulose biomass has been considered a promising venture. In this study, microwave, alkali-pretreated empty fruit bunch (EFB) was used as the substrate, utilizing pelletized filamentous Rhizopus oryzae NRRL 395 and cellulolytic enzymes for lactic acid production in a fed-batch simultaneous saccharification and fermentation (SSF) process. Insoluble solids generally do not affect the SSF process until a certain concentration is exceeded. To achieve a high lactic acid concentration in the broth, a high solids loading was required to allow a higher rate of glucose conversion. However, the results revealed a decrease in the final lactic acid yield when running SSF at a massive insoluble solids level. High osmotic pressure in the medium led to poor cellular performance and caused the Rhizopus oryzae pellets to break down, affecting the lactic acid production. To improve the process performance, a fed-batch operation mode was used. The fed-batch operation was shown to facilitate higher lactic acid yield, compared with the SSF batch mode. Enzyme feeding, as well as substrate feeding, was also investigated as a means of enabling a higher dry matter content, with a high glucose conversion in SSF of cellulose-rich EFB.

  • Researchpp 3813-3824Xiong, J., Yu, S., Zhu, H., Wang, S., Chen, Y., and Liu, S. (2016). "Dissolution and structure change of bagasse cellulose in zinc chloride solution," BioRes. 11(2), 3813-3824.AbstractArticlePDF

    The dissolution of sugarcane bagasse cellulose (SBC) in zinc chloride solution was studied at elevated temperatures. Based on single factor experiments, the effects of zinc chloride mass fraction, dissolution time, temperature, and bagasse cellulose mass fraction were investigated by an orthogonal experiment, and the optimal dissolution conditions were obtained. The dissolution process of bagasse cellulose was observed under a microscope. Additionally, the original SBC and regenerated SBC were both characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Temperature was found to be the most important factor affecting dissolution time. The best dissolving process took place at 85 °C to dissolve 2% SBC in 85% zinc chloride for 210 min. It was shown that the zinc chloride was a direct solvent for SBC. After regeneration of cellulose in zinc chloride, the crystallinity of cellulose was decreased greatly, from 77% to 54%, its crystalline form was transformed from cellulose I to cellulose II, its thermal decomposition temperature was reduced, its thermal stability was slightly decreased, and its internal structure was disrupted.

  • Researchpp 3825-3839Kusumoto, N., Takata, K., and Kurimoto, Y. (2016). "Mechanical properties and dimensional stabilities of wood-polypropylene composites prepared using mechanochemically acetylated Japanese cedar (Cryptomeria japonica) wood meal," BioRes. 11(2), 3825-3839.AbstractArticlePDF

    The scale-up of a mechanochemical acetylation operation using 100-L ball mills was performed to produce acetylated Japanese cedar (Cryptomeria japonica) wood meal for wood-polypropylene composite (WPC) production. Finely and coarsely acetylated wood meals (AWMs) were successfully produced with approximately 21% and 19% weight percent gains (WPG), respectively, which was close to the theoretical value. The mechanical properties of WPCs showed similar, rather weak strength compared with the AWM-filled WPCs without maleic anhydride-grafted polypropylene (MAPP) as a compatibilizing agent; however, coarse AWM-filled WPCs showed similar or higher mechanical properties than untreated wood meal (UWM)-filled WPCs when MAPP was added. Clear enhancements in the dimensional stability of AWM-filled WPCs were observed, but no significant differences in dimensional stability were observed between WPCs filled with fine and coarse AWMs, even when MAPP was added. Morphological analyses of the fracture surface showed the retention of some wood cell wall structures in coarse AWM, and fine loadings of the thermoplastic into the lumen were clearly observed. These properties were not found on the fracture surface of fine AWM-filled WPCs; therefore, high polymer loadings into the retained wood structure with high interfacial adhesion by MAPP could be suggested for improving the mechanical properties of coarse AWM-filled WPCs.

  • Researchpp 3840-3855Abd Hamid, S. B., Chowdhury, Z. Z., Karim, M. Z., and Ali, M. E. (2016). "Catalytic isolation and physicochemical properties of nanocrystalline cellulose (NCC) using HCL-FeCl3 system combined with ultrasonication," BioRes. 11(2), 3840-3855.AbstractArticlePDF

    This research emphasizes the isolation of nanocrystalline cellulose (NCC) from palm tree cellulose (PTC) and α-cellulose (AC), using acidic FeCl3-assisted catalytic pretreatment coupled with ultrasonication. The cavitation effect of ultrasonication affects the microstructure of the fibers, ultimately enhancing the crystallinity index of the prepared nanocrystalline cellulose (NCC) sample. In this research, Fourier transform infrared spectroscopy (FTIR) was used to identify the specific functional groups on both types of NCC sample. X-ray diffraction (XRD) analysis demonstrated that the isolated NCC from PTC and AC showed a higher crystallinity index of 73.51% and 89.03%, with diameters of 20 to 70 nm and 15 to 50 nm, respectively. The change in surface morphological features was observed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopic (TEM) analysis. It was observed that PTC-based NCC had higher thermal stability than the starting cellulosic sample, whereas NCC isolated from AC showed an opposite trend of reduced thermal stability relative to the raw sample. The results indicated that catalytic acid hydrolysis with ultrasonication was able to yield up to 80.88% and 81.20% of NCC from PTC and AC, respectively, which is comparatively high enough for economic viability of the process.

  • Researchpp 3856-3874Li, L., Wang, X., and Wu, F. (2016). "Chemical analysis of densification, drying, and heat treatment of Scots pine (Pinus sylvestris L.) through a hot-pressing process," BioRes. 11(2), 3856-3874.AbstractArticlePDF

    This study investigated a new potential hot-pressing method for wood modification, in which densification, drying, and heat-treatment were carried out in sequence. The effects of heat treatment on the chemical components of wood were evaluated. The specimens were treated at different temperatures (180 to 220 °C) for 2 to 5 h. Holocellulose, α-cellulose, and lignin were extracted from the treated and untreated milled wood. The changes in these components were analyzed by thermogravimetry (TG) and Fourier-transform infrared spectroscopy (FTIR). Due to its amorphous structure, most hemicelluloses were degraded when it was exposed to 220 °C for 3 h and to 200 °C for 5 h. Conversely, the lignin contents increased continuously throughout the treatment due to the loss of polysaccharides and the formation of cross-links. Because of the crystallinity, α-cellulose degradation was slight. According to the analysis of functional groups, FTIR showed treated wood was more hydrophobic than the untreated one.

  • Researchpp 3875-3889Sri Aprilia, N. A., Davoudpour, Y., Zulqarnain, W., Abdul Khalil, H. P. S., Mohamad Hazwan, C. I. C., Hossain, M. S., Dungani, R., Fizree, H. M., Zaidon, A., and Mohamad Haafiz, M. K. (2016). "Physiocochemical characterizationof microcrystalline cellulose extracted from kenaf bast," BioRes. 11(2), 3875-3889.AbstractArticlePDF

    Microcrystalline cellulose (MCC) was successfully prepared from bleached kenaf bast fiber through hydrochloric acid hydrolysis. The influence of hydrolysis time (1 to 3 h) on the MCC physicochemical properties was examined. Scanning electron microscopy (SEM), X-ray diffraction (XRD), particle size analysis, Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA) were utilized to characterize the isolated MCC. According to FTIR analysis, the chemical composition of MCC was not changed with the reaction time. The reaction times, however, did affect the thermal stability of MCC. The thermal stability decreased linearly with increasing hydrolysis time. The optimum hydrolysis time was determined based on the morphological, structural, and thermal properties of the kenaf bast MCC.

  • Researchpp 3890-3903Hosseinihashemi, S. K., Salem, M. Z. M., Hossein Ashrafi , S. K. and Latibari, A. J. (2016). "Chemical composition and antioxidant activity of extract from the wood of Fagus orientalis: Water resistance and decay resistance against Trametes versicolor," BioRes. 11(2), 3890-3903.AbstractArticlePDF

    Extracted wood samples of Fagus orientalis with different solvents were analyzed for their antifungal activity against white-rot fungus (Trametes versicolor) in an agar plate. The most active extract was analyzed for its antioxidant activity by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method, and the chemical composition were analyzed using gas chromatography-mass spectrometry. After the solvent removal of extractives, especially using chloroform (Chl) and Chl-water mixture, losses in the resistance of beech wood had occurred. However, Chl extract was found to be the most active antifungal agent, and the weight loss (30.38%) of specimens after 14 weeks of incubation was higher than that of other extracted specimens. At the concentration of 0.016 mg/mL, the highest activity observed was by Chl extract (89.45%), which was lower than the value of vitamin C (96.63%) at the same concentration. The lowest weight loss values obtained from the decay test were 0.35% and 0.64% for ethanol and ethanol-water extracted beech wood samples, respectively. The highest weight loss values were 30.38% and 23.98% for Chl and Chl-water extracted samples, respectively.

  • Researchpp 3904-3913Björngrim, N., Hagman, O., and Wang, X. (2016). "Moisture content monitoring of a timber footbridge," BioRes. 11(2), 3904-3913.AbstractArticlePDF

    Construction of modern timber bridges has greatly increased during the last 20 years in Sweden. Wood as a construction material has several advantageous properties, e.g., it is renewable, sustainable, and aesthetically pleasing, but it is also susceptible to deterioration. To protect wood from deterioration and ensure the service life, the wood is either treated or somehow covered. This work evaluates a technology to monitor the moisture content in wood constructions. Monitoring the moisture content is important both to verify the constructive protection and for finding areas with elevated levels of moisture which might lead to a microbiological attack of the wood. In this work, a timber bridge was studied. The structure was equipped with six wireless sensors that measured the moisture content of the wood and the relative humidity every hour. Data for 744 days of the bridge are presented in this paper. Results show that the technology used to monitor the bridge generally works; however, there were issues due to communication problems and malfunction of sensors. This technology is promising for monitoring the state of wood constructions, but a more reliable sensor technology is warranted continuous remote monitoring of wood bridges over long periods of time.

  • Researchpp 3914-3922Khademieslam, H., and Kalagar, M. (2016). "Evaluation of the bending strength, impact strength, and morphological properties of wheat straw fiber/paper mill sludge/polypropylene composites," BioRes. 11(2), 3914-3922.AbstractArticlePDF

    Composite production of polypropylene polymers was considered in this work as the matrix, filled with the fiber of wheat straw and paper mill sludge; different ratios were evaluated relative to their potential as reinforcement materials. Maleic anhydride polypropylene (MAAP) was used at 3% by weight. The bending modulus of elasticity of the composites significantly increased with both types of filler. The highest bending modulus of the composites was found with 40% of paper mill sludge. Using 40% wheat straw fiber decreased bending strength, but the addition of paper mill sludge increased bending strength. The highest bending strength of the composites related to polypropylene/10% of wheat straw fiber and 30% of paper mill sludge. In terms of impact strength, the use of paper mill sludge had a higher impact on strength than wheat straw fiber composites. The inclusion of MAPP improved the mechanical properties of all composites. Scanning electron micrographs showed that the composite paper mill sludge improved the adhesion and dispersion of the filler (paper mill sludge/fiber paper instead of wheat) in the matrix.

  • Researchpp 3923-3936Chen, W., Shi, S., Nguyen, T., Chen, M., and Zhou, X. (2016). "Effect of temperature on the evolution of physical structure and chemical properties of bio-char derived from co-pyrolysis of lignin with high-density polyethylene," BioRes. 11(2), 3923-3936.AbstractArticlePDF

    Bio-chars were produced by co-pyrolysis of lignin with high-density polyethylene at 350 °C, 450 °C, and 550 °C. X-ray diffraction (XRD), Raman spectroscopy, automated surface area and pore size analysis, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR) spectroscopy were performed on bio-char to reveal the effect of temperature on its physical structure and chemical properties. All of the bio-chars demonstrated a highly disordered, turbostratic structure and exhibited a wide pore distribution. Dramatic losses of carbonyl, hydroxyl, and C-H groups indicated the development of condensed aromatic structure in the bio-chars. Specifically, biochar produced at 450 °C showed the highest degree of aromaticity, which is the relative content of aromatic structure with small fused rings and free radical concentration. This structure has more potential application in composite production and as solid fuel for its combustion or gasification. Moreover, biochar produced at 550 °C had the greatest porosity development, favoring its use as a precursor for activated carbon production.

  • Researchpp 3937-3946Li, R., Shu, Z., Qian, L., Zhou, L., Liu, Y., and Liu, S. (2016). "Magnetic biomorphic BaFe12-xCrxO19 ceramics with multilayer wall structure made from spruce templates," BioRes. 11(2), 3937-3946.AbstractArticlePDF

    BaFe12-xCrxO19 (x = 0.0, 0.1, 0.2, 0.3, and 0.4) ferrite ceramics were prepared by a sol-gel method using spruce sapwoods as the templates. The prepared materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and a magnetic property measurement system (MPMS). The prepared materials maintained a multilayer wall structure of spruce sapwoods. All samples presented the single-phase of the magnetoplumbite barium hexaferrite. The saturation magnetization initially increased until it reached a maximum value at x= 0.2 and then decreased in three directions (parallel cross section, parallel radial section, and parallel tangential section). The coercivity decreased monotonously when measured in three directions. However, the coercivity was obviously lower in the parallel cross section direction than in the other directions because of the structural anisotropy caused by the multilayered wall structure.

  • Researchpp 3947-3963Yang, T. H., Chang, F. R., Lin, C. J., and Chang, F. C. (2016). "Effects of temperature and duration of heat treatment on the physical, surface, and mechanical properties of Japanese cedar wood," BioRes. 11(2), 3947-3963.AbstractArticlePDF

    This study investigated the application of heat to wood samples from Japanese cedar trees (Cryptomeria japonica) of small and medium diameters to evaluate the effects of both the temperature and duration of treatment on its surface, physical, and mechanical properties. The results indicate that the density, moisture content, and hygroscopicity of the wood samples decreased as the treatment temperature and duration increased, and the mass loss increased under the same conditions. Additionally, the dimensional stability of the wood improved in response to increased temperatures and prolonged durations. These results suggest that heat treatment can be used to improve the dimensional stability of wood. The surface color of the wood darkened progressively with increasing treatment temperature and duration, and the hydrophobicity of the wood sample improved as a result of the heat treatment. In contrast to the untreated wood, the heat-treated wood exhibited decreased mechanical properties with an increase in the treatment temperature and duration.

  • Researchpp 3964-3971Xu, Y., Zhang, W., Yue, X., and Zhang, D. (2016). "Determination of aluminum in bamboo pulp black liquor by ICP-AES," BioRes. 11(2), 3964-3971.AbstractArticlePDF

    Sodium aluminosilicate scaling in evaporators during alkali recovery is often associated with the concentration of aluminum and silicon in black liquor. The scaling problems are widespread during the utilization of non-wood raw materials. This study established a fast, reliable, and precise method to determine the aluminum concentration in bamboo black liquor by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Prior to ICP-AES measurements, black liquor samples were digested in an automatic electric heating assisted digestion system. After optimizing the digestion, ICP-AES testing showed that the recovery of the element was 96.2% to 99.9% and the relative standard deviation (RSD) was 0.07% to 0.52%. Additionally, comparative data for the concentration of analytes was obtained by flame atomic absorption spectrometry (FAAS). This technique will be useful for assessing the scaling properties of black liquor in the alkali recovery phase.

  • Researchpp 3972-3986Zhang, L., You, T., Zhou, T., Zhang, L., and Xu, F. (2016). "Determining lignin degradation in white-rot fungi-treated Sacrau poplar: Lignin structural changes and degradation compound analysis," BioRes. 11(2), 3972-3986.AbstractArticlePDF

    Determining the structural changes of lignin during bio-treatment will facilitate the understanding of biomass recalcitrance during the sustainable production of chemicals and fuels. However, the analysis of milled wood lignin (MWL) cannot completely elucidate the complex and irregular structural changes therein. In this study, MWL and lignin degradation compounds were extracted from white-rot fungi-treated poplar in order to unveil the degradation process. Results from MWL revealed that the cleavage of β-O-4′ linkages (from 76.4/100Ar to 31.5/100Ar) and the degradation of β–β′and β-5′ linkages clearly occurred, resulting in a decrease in molecular weight. In addition, G-type lignin was more degraded than S-type lignin, with a slightly elevated S/G ratio from 1.13 to 1.29. Further analyses of lignin degradation compounds confirmed these results by showing a high amount of conjugated and unconjugated C=O functionalities. Furthermore, the degradation product of G-type lignin (vanillin) was detected by 2D HSQC NMR and GC-MS. This study of lignin alterations during white-rot fungi treatment could be beneficial for the sustainable production of chemicals, materials, and fuels from renewable plant resources.

  • Researchpp 3987-4005Barčić, A. P., Motik, D., Oblak, L., and Vlosky, R. (2016). "Management activity linkages to innovation deconstruction: An exploratory study of the furniture industry in Croatia," BioRes. 11(2), 3987-4005.AbstractArticlePDF

    Corporate leaders often view innovation as a key contributor to superior profits, market sharing, and competitive positioning. However, confusion regarding the definition of innovation, how to create it, and how to implement it remains. In countries that are recent European Union members, little research has been done on innovation and how innovation is related to corporate management activities. In this study, the linkages were examined in the Croatian furniture industry. The first part of the study was to deconstruct innovation into three components: product innovation, production process innovation, and human resource innovation. The second part of the study evaluates the relationships between these innovation components and four company management activities/factors (research and development investments, company flexibility, export activity, and the Internet usage) were examined. Scale testing resulted in valid deconstruction measures of innovation. Hypothesized correlations between innovation components and company management factors were supported, although the results were not fully consistent with those of previous studies.

  • Researchpp 4006-4016Cheng, S., Huang, A., Wang, S., and Zhang, Q. (2016). "Effect of different heat treatment temperatures on the chemical composition and structure of Chinese fir wood," BioRes. 11(2), 4006-4016.AbstractArticlePDF

    The properties of wood can be improved after heat-treatment. There have been many studies dealing with mechanical properties and chemical modifications of heat-treated wood. The purpose of this paper is to provide a new analysis method, to give better insights on the hemicelluloses, cellulose, and lignin contents of heat-treated wood by using Fourier transform infrared (FT-IR) and two-dimensional infrared (2D-IR) spectroscopies. The FT-IR spectra results showed progressive degradation in the carbonyl groups of the glucuronic acid units and degradation of the pyranose of hemicelluloses. These changes were measured as the percentage decrease of crystalline cellulose and the loss of C=O and C=C groups linking together the aromatic skeleton of lignin. The 2D-IR spectra showed the appearance of 5 × 5 peak clusters in the 1000 to 1200 cm-1 region, which could account for the hemicellulose degradation. In addition, changes in the degree of sensitivity at 1627 and 1509 cm-1 coincided with cross-linking reactions among the aromatic units in the lignin molecules.

  • Researchpp 4017-4024Du, C., Liu, M., Li, B., Li, H., Meng, Q., and Zhan, H. (2016). "Cellulose nanocrystals prepared by persulfate one-step oxidation of bleached bagasse pulp," BioRes. 11(2), 4017-4024.AbstractArticlePDF

    This article describes a novel one-step method to prepare cellulose nanocrystals (CNCs) from bleached bagasse pulp via ammonium persulfate (APS) oxidation. The obtained persulfate oxidation cellulose nanocrystals (POCNs) were characterized for their microstructure, crystal properties, and chemical composition. The POCNs were successfully prepared with a total yield of 44.6%. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements indicated that the POCNs had an average length of 150 to 300 nm and an average width of 10 to 30 nm, as well as a rod-like morphology. Fourier transform infrared (FTIR) spectroscopy confirmed the introduction of carboxyl groups on the surface of cellulose. The X-ray diffraction (XRD) spectra proved the existence of cellulose type I, with a highly crystalline nature (79.2%), and thermogravimetric analysis (TGA) showed that the thermal stability decreased.

  • Researchpp 4025-4036Seki, M., Tanaka, S., Miki, T., Shigematsu, I., and Kanayama, K. (2016). "Extrudability of solid wood by acetylation and in-situ polymerisation of methyl methacrylate," BioRes. 11(2), 4025-4036.AbstractArticlePDF

    Recently, a processing technique resembling plastic-type forming has been developed for solid wood. To improve the recyclability of the formed products, thermoplastics were used as a binder. In this study, a hydrophobic monomer of methylmethacrylate (MMA) was used as a thermoplastic binder and was impregnated into wood, then polymerised by heat to form polymethylmethacrylate (PMMA). The effects of wood acetylation, a hydrophobising treatment of wood, on the extrudability of solid wood impregnated with PMMA (wood-PMMA composite) during extrusion were investigated. The acetylated wood was found to swell much more after the PMMA treatment than the untreated wood. The extrusion loads obtained from capillary fluidity tests of the acetylated wood-PMMA composite were lower than those of untreated composite. The fluidity improvement by acetylation can be attributed to a weakening of the cohesive interactions in the wood polymer, and this is primarily caused by the acetylation reaction itself. When the acetylated wood-PMMA composite was repeatedly extruded, the starting load of the extrusion decreased with increasing extrusion repetitions, probably as a result of decreasing wood particle size.

  • Researchpp 4037-4054Vanhatalo, K., Maximova, N., Perander, A. M., Johansson, L. S., Haimi, E., and Dahl, O. (2016). "Comparison of conventional and lignin-rich microcrystalline cellulose," BioRes. 11(2), 4037-4054.AbstractArticlePDF

    Three microcrystalline cellulose (MCC) samples were manufactured from bleached and unbleached softwood kraft pulp, and their properties were compared to those of the commercial MCC, Avicel PH-101. One of the produced samples retained a large portion of lignin (10.3%), while the two others retained only some. The physical, chemical, thermogravimetric, and molecular properties were analyzed. The presence of lignin caused a substantial effect on the thermogravimetric and chemical properties of the MCC, as well as on its surface characteristics. The lignin-containing sample degraded at lower temperatures, and its UV Raman spectra had a high intensity aromatic band (1600 cm-1) arising from the lignin. X-ray photoelectron spectroscopy confirmed a high surface lignin coverage (40%) in this specimen only. Particle size and BET surface area measurement results varied in some limits between MCCs, while the cellulose crystallinity index showed almost equal values between 0.82 and 0.84. This work introduces a new wood-based product, the lignin-containing MCC, comparable in properties to the wide-marketed Avicel.

  • Researchpp 4055-4068Ren, R., Shang, T., Jin, X., and Gao, J. (2016). "Preparation of N-, S-Co-doped activated carbons derived from waste medium density fiberboard for supercapacitors," BioRes. 11(2), 4055-4068.AbstractArticlePDF

    Nitrogen-, sulfur-co-doped activated carbons were obtained from sulfur-modified and nitrogen-doped activated carbons that were prepared from waste medium density fiberboard. The electrochemical capacitive performance of the activated carbon samples obtained was investigated in 7.0 M KOH electrolyte. The morphology, structure, and surface properties of the samples were investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 adsorption, X-ray photoelectron spectroscopy (XPS), and elemental analysis. The S-doping could be tuned by controlling the dosage of sulfur sublimed. Because of the introduction of sulfur functional groups, the prepared carbons exhibited better conductivity and higher specific capacitance, reaching 264 F/g under a current density of 50 mA/g and a 7.0 mol/L KOH electrolytic solution. A mechanism for improving the conductivity and capacitive performance of sulfur functional groups on activated carbons was discussed.

  • Researchpp 4069-4085Feng, J., Zhang, H., He, H., Huang, X., and Shi, Q. (2016). "Effects of fungicides on mold resistance and mechanical properties of wood and bamboo flour/high-density polyethylene composites," BioRes. 11(2), 4069-4085.AbstractArticlePDF

    The main objective of this study was to determine the mold resistance and mechanical properties of fungicide-treated wood and bamboo flour/high density polyethylene (HDPE) composites. Zinc borate (ZB), 4,5-dichloro-2-octyl-isothiazolone (DCOIT), zinc pyrithione (ZPT), and carbendazim (MBC) were used as fungicides. Then, treated and untreated samples were exposed to mold fungi (Aspergillus niger, Trichoderma viride, Penicillium funiculosum, and Aureobasidium pullulans) for 28 days. Mechanical properties, including the tensile strength, modulus of elasticity (MOE), modulus of rupture (MOR), and impact strength of treated and untreated composites, were evaluated. The experimental results indicated that incorporation of all four fungicides greatly improved the mold resistance of wood flour/HDPE composites. ZB-, DCOIT-, and ZPT-treated bamboo flour/HDPE composites were also more resistant to mold fungi, while no inhibitory effect on mold growth was observed for MBC-treated bamboo flour/HDPE composites. In most cases, fungicides lowered the tensile strengths and MOR of wood flour/HDPE samples but increased the impact strengths of wood flour/HDPE composites and tensile strengths and MOE of bamboo flour/HDPE composites, while other mechanical properties behaved differently. Accordingly, some fungicides can be effectively used as preservatives for both wood flour/HDPE and bamboo flour/HDPE composites.

  • Researchpp 4086-4103Wang, P., Fu, Y., Shao, Z., Zhang, F., and Qin, M. (2016). "Structural changes to aspen wood lignin during autohydrolysis pretreatment," BioRes. 11(2), 4086-4103.AbstractArticlePDF

    Aspen wood was subjected to autohydrolysis as a pre-treatment to characterize the structural changes occurring in lignin fractions during the pre-treatment process. Milled wood lignin (MWL) was isolated from both the native aspen wood and hydrolyzed wood chips, and its structural features were characterized by Fourier transform infrared (FT-IR), quantitative 13C, two-dimensional heteronuclear single quantum coherence (2D HSQC), and 31P nuclear magnetic resonance (NMR) spectroscopies, gel permeation chromatography/multi-angle laser light scattering (GPC-MALLS), and thermal analysis. The lignin remaining in the hydrolyzed wood chips revealed more phenolic OH groups, fewer aliphatic OH groups, higher syringyl/guaiacyl ratios (S/G), higher molecular weights, and narrower polydispersities than the native lignin of aspen wood. The inter-unit linkages of β-O-4 were noticeable cleaved, but the condensed structures in the lignin formed when undergoing autohydrolysis of high severity, resulting in elevated amounts of C-C linkages. Moreover, it was found that autohydrolysis promoted the removal of -OCH3 groups and increased the thermal stability of lignin fractions.

  • Researchpp 4104-4112Jiang, Q., Yang, G., Wang, Q., Sun, Q., Lucia, L. A., and Chen, J. (2016). "Ultrasound-assisted xylanase treatment of chemi-mechanical poplar pulp," BioRes. 11(2), 4104-4112.AbstractArticlePDF

    Xylanase treatment can be an environmentally friendly way to improve the formability and drainability of chemi-mechanical pulp (CMP). Improvements in xylanase treatment efficiency are possible with application of an ultrasonic wave via the cavitation effect. Results showed that the specific surface area (SSA) of the combined treated pulp increased by 14.6% at an ultrasonic treatment of 30 min and xylanase dosage of 10 U/g, in comparison to xylanase treatment alone. Also, the drainability of xylanase-treated pulp increased from 450 to 500 mL, and it further increased to 775 mL with ultrasonic-assisted xylanase treatment. Morphological characterization of pulps showed an enhanced fibrillation for the combined treatment, as shown by scanning electron microscope (SEM) images. In addition, the dimensions of treated fibers were negligibly affected.

  • Researchpp 4113-4133Gao, Y., Yu, B., Wu, K., Yuan, Q., Wang, X., and Chen, H. (2016). "Physicochemical, pyrolytic,and combustion characteristics of hydrochar obtained by hydrothermal carbonization of biomass," BioRes. 11(2), 4113-4133.AbstractArticlePDF

    Effects of the type of biomass and temperature, with longer residence time, on physicochemical characteristics of hydrochar were investigated. Different carbonization conditions were applied with the goal of producing hydrochars having better physicochemical properties. After the carbonization process, the pyrolysis and combustion behaviors of hydrochar were evaluated. The effect of temperature on the chemical characteristics of hydrochar was obvious. The yield and heating value of hydrochar were high for raw materials. Even though the yield of hydrochar from water hyacinth was low, the morphology of this hydrochar was the best among all biomass samples tested. Hydrochar derived from water hyacinth can be used as a new kind of carbon material, which can improve the utilization of biomass resources. The pyrolysis and combustion behaviors of hydrochar were studied; the corresponding kinetic parameters were determined by thermogravimetric (TG) analysis. With increasing heating rate, the TG and differential thermogravimetric (DTG) curves moved to high temperatures. The combustion of hydrochar had two stages: volatilization and fixed carbon combustion. The activation energy of the wheat straw was 37 kJ/mol, and the activation energy of the water hyacinth was 51 kJ/mol. This data indicated that the combustion of water hyacinth hydrochar was difficult.

  • Researchpp 4134-4145Sanyang, M. L., Sapuan, S. M., Jawaid, M., Ishak, M. R., and Sahari, S. (2016). "Effect of sugar palm-derived cellulose reinforcement on the mechanical and water barrier properties of sugar palm starch biocomposite films," BioRes. 11(2), 4134-4145.AbstractArticlePDF

    In this study, sugar palm-derived cellulose (SPC) composites were prepared and utilized as reinforcement material to improve the mechanical and water vapor barrier properties of sugar palm starch (SPS)-based films. Cellulose-reinforced SPS composite films (SPS-C) were prepared with different SPC loadings (1 to 10 wt.%) using a solution casting method. The mechanical properties of the composite films showed increased tensile strength and modulus, while the elongation at break decreased with SPC loading. Adding 1 wt. % SPC loading significantly improved the water vapor permeability (WVP) of the composite film by 63.53% compared with the neat SPS film. This was ascribed to the high compatibility between the SPC and SPS matrices, which was supported by the field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR) results.

  • Researchpp 4146-4158Wu, R., Huang, P., and He, B. (2016). "Preparation and characterization of regenerated cellulose microspheres and the adsorption of pectinase," BioRes. 11(2), 4146-4158.AbstractArticlePDF

    Porous cellulose beads were prepared through a simple, facile, and inexpensive method. The resultant microspheres exhibited good spherical shape with a diameter of 1 to 2 mm. Their morphology, pore structure, and physical properties were characterized by scanning electron microscopy, X-ray diffraction, and nitrogen adsorption. The regenerated cellulose was shown by scanning electron microscopy images to have a three-dimensional porous structure, which led to a BET surface area as large as 108 m2/g. These qualities make the beads potentially useful as adsorbents or carriers. The beads remained in the cellulose I structure. Finally, the cellulose beads were tested for the adsorption of pectinase; adsorption was a favorable spontaneous process. Moreover, adsorption was in agreement with the Langmuir isotherm with a capacity of 7.40 mg/g, signifying that pectinase adsorption was a monolayer sorption. Adsorption followed an intraparticle diffusion kinetic model, indicating that intraparticle diffusion was the rate-controlling mechanism. This information will aid in the potential utilization of regenerated cellulose microspheres as supports for pectinase.

  • Researchpp 4159-4167Tao, Y., Li, P., and Cai, L. (2016). "Effect of fiber content on sound absorption, thermal conductivity, and compression strength of straw fiber-filled rigid polyurethane foams," BioRes. 11(2), 4159-4167.AbstractArticlePDF

    Rigid polyurethane (PUR) foam is one of the most important insulating materials used today in the construction industry and is the main insulation material used in the global appliances industry. This study developed rice straw fiber-filled PUF (RPUF) and wheat straw fiber-filled PUF (WPUF) and explored the morphology, sound absorption properties, heat transfer, and compressive strength of the PUF composites. The results indicated that, with the higher fiber content, more open cells were observed in SEM images of the composites. The average sound absorption coefficients (ASAC) of both WPUF and RPUF were significantly increased when 5 per hundred polyols (php) by weight and 10 php fiber contents were added. When fiber contents of 15 php and 20 php were utilized, ASAC reduced due to the tortuosity of cells and large holes in the foam. The sound absorption coefficient (SAC) first increased, then decreased, and increased finally as the sound frequency increased from 100 to 2000 Hz for the two composites. The thermal conductivities of both WPUF and RPUF first decreased and then increased as the fiber content increased from 0 to 20 php. When 5 and 10 php straw contents was added, the thermal conductivities were reduced by 25% to 50% compared to that of the pure PU form (0 php), indicating that the improved thermal insulation ability was obtained. The composite compressive strength was reduced by 19% to 28% due to the fiber addition.

  • Researchpp 4168-4185Toghyani, A. E., Matthews, S., Eskelinen, H., Kärki, T., and Varis, J. (2016). "Feasibility assessment of a wood-plastic composite post-production process: Formability," BioRes. 11(2), 4168-4185.AbstractArticlePDF

    Wood-plastic composites (WPCs) – one of a number of promising classes of materials in the manufacturing industries – are experiencing rapid market growth. However, the favorable characteristics of this material and the development of new production processes and post-production processes suggest even greater potential for utilization of WPCs. This paper evaluates the formability of an extruded WPC material comprising nearly 45% wood fiber, 50% thermoplastic, and 5% of other additives in a novel extrusion-based post-production process. The press-forming process described in this work is used to form and cut the pre-determined profile shape to obtain the final product. After preliminary tests to determine the suitable temperature range, dimensions, and roughness range for a post-extrusion hot-pressing process of a sample WPC product, a diverse set of product quality tests were then conducted on pre-heated sheets of WPC material using forming tools attached to a hydraulic press. The forming process had high accuracy with respect to dimensional precision and acceptable repeatability. The forming process also reduced the surface roughness of the material. The test results clearly demonstrated the dependence of final product quality on the quality of the original extruded WPC profiles used, e.g., with respect to the thickness variation of the material.

  • Researchpp 4186-4200Díaz-Godínez, G., Téllez-Téllez, M., Rodríguez, A., Obregón-Barbosa, V., Acosta-Urdapilleta, M., and Villegas, E. (2016). "Enzymatic, antioxidant, antimicrobial, and insecticidal activities of Pleurotus pulmonarius and Pycnoporus cinnabarinus grown separately in an airlift reactor," BioRes. 11(2), 4186-4200.AbstractArticlePDF

    Crude extract samples of Pleurotus pulmonarius and Pycnoporus cinnabarinus were taken during growth in liquid broth in an airlift reactor. Growth was monitored indirectly by sugar consumption and pH profile. During growth Pleurotus pulmonarius consumed glucose more slowly than Pycnoporus cinnabarinus, reaching a final pH of 8.0. In contrast, Pycnoporus cinnabarinus started consuming glucose faster from the beginning to the end with a pH of 3.6, suggesting the production of different metabolites while they grow in the same culture broth. Additionally, antioxidant activity, polyphenol and flavonoid contents, as well as laccase and hydrolase activities were quantified in the culture extracts during the fermentation. Pleurotus pulmonarius showed higher antioxidant activity than Pycnoporus cinnabarinus. Both fungi have a very low polyphenol and flavonoid content. Values of amylase and pectinase activities were similar in crude extracts of both fungi; however, cellulase, xylanase, invertase, and laccase activities showed higher levels in crude extract of Pleurotus pulmonarius. Antimicrobial and insecticidal activities were also evaluated in each crude extract. In fact, Pycnoporus cinnabarinus presented a very strong bacteriostatic and bactericidal effect against Escherichia coli and Staphylococcus aureus and reliably killed Diatraea magnifactella larvae, while Pleurotus pulmonarius did not showed any negative effect on the growth of these bacteria or larvae.

  • Researchpp 4201-4211Saharinen, E., Särkilahti, A., Salminen, L. I., and Heinemann, S. (2016). "The effect of wood alignment on wood grinding - Part 1: Properties of pulp and fines revealed in the grinding mechanism," BioRes. 11(2), 4201-4211.AbstractArticlePDF

    In industrial wood grinding, logs are pressed against a rotating stone, with the logs and fiber axis parallel to the axis of the stone. The objective of this study is to clarify how the wood alignment affects the process and pulp properties. In this research, wood blocks were fed into a laboratory grinder with various alignments in relation to the surface of the grinding stone. The effects of the alignment on the properties of the pulp and the amount and quality of fines were measured. A grinding mechanism was proposed. The results show that the pulp quality is very sensitive to the angle between the stone surface and the log. In gentle refining, the fiber structure is loosened by fatigue before it is bent on the surface; pressure pulses produce fibrillar material, and fibers develop toward having good bonding ability. In forced grinding, the process is “violent”, and the fiber wears and becomes crushed immediately on the surface into small particles with low bonding ability.

  • Researchpp 4212-4225Chen, C., Zhang, Y., Sun, G., Wang, J., and Wang, G. (2016). "Windmill palm fiber/polyvinyl alcohol coated nonwoven mats with sound absorption characteristics," BioRes. 11(2), 4212-4225.AbstractArticlePDF

    Windmill palm single fibers (WPSFs) and fiber bundles (WPFBs) were extracted from a windmill sheath mesh. For the palm fiber acoustic application, WPSFs/WPFBs nonwoven materials and windmill palm fiber (WPF)/polyvinyl alcohol (PVA) coated nonwoven mats were developed. The effects of conditions such as the thickness and surface density of the materials and the concentration of PVA were studied. The sound absorption coefficients of all of the samples were measured using an impedance tube instrument. The statistical significance of the differences between these materials was tested using Duncan’s grouping method. Based on the results, the windmill palm fiber can be regarded as appropriate for use as a sound absorbing material. The addition of PVA was an effective way to improve the acoustic properties of the WPF/PVA coated nonwoven mats. This coated mat exhibited a greater ability to absorb sound than WPSFs/WPFBs nonwoven materials. The acoustic properties of the materials exhibited good results, with an average sound absorption coefficient of 0.38 when the concentration of PVA was 1 wt.%.

  • Researchpp 4226-4236Liu, Y., Sun, B., Wang, Z., and Ni, Y. (2016). "Mechanical and water vapor barrier properties of bagasse hemicellulose-based films," BioRes. 11(2), 4226-4236.AbstractArticlePDF

    The film-forming ability of bagasse hemicellulose and its potential for packaging were investigated in terms of its mechanical and water vapor barrier properties. The films were prepared under various hemicellulose concentrations, chitosan/glycerol amounts (based on the amount of hemicellulose), and temperatures. These were subsequently evaluated by measurement of their mechanical and water vapor barrier properties. Bagasse hemicellulose-based films with higher tensile strengths were obtained at higher hemicellulose concentrations. Scanning electron microscope images showed that the bagasse hemicellulose-based films did not have pores less than one micron in size, suggesting compatibility between the hemicelluloses and the other components present in the films. Moreover, the tensile strength, elongation, and water vapor barrier of the film increased by approximately 124%, 115%, and 48%, respectively, when the drying temperature increased from 25 to 55 °C. These results indicate that the bagasse hemicellulose can be used as part of the raw material for films with good barrier and mechanical properties.

  • Researchpp 4237-4251Valdez-Vazquez, I., Torres-Aguirre, G. J., Molina, C., and Ruiz-Aguilar , G. M. L. (2016). "Characterization of a lignocellulolytic consortium and methane production from untreated wheat straw: Dependence on nitrogen and phosphorus content," BioRes. 11(2), 4237-4251.AbstractArticlePDF

    Impacts of microbial diversity and macronutrients levels (expressed as C:N and C:P ratios) on the methane production from an untreated lignocellulosic feedstock were assessed. Next-generation sequencing technology revealed the bacterial diversity of a lignocellulolytic inoculum. This inoculum comprised 75 bacterial species that were well distributed in 14 phyla, 67% of which belonged to Firmicutes and Bacteroidetes. The families Ruminococcaceae, Clostridiaceae, Bacteroidaceae, Bacillaceae, and Fibrobacteraceae comprised 46% of the identified families and were associated with hydrolytic members. Nutrient adjustment reduced 40% of the length of the lag phase and doubled methane production rate compared with a control. The highest methane production of 0.197 m3 per kg of total volatile solids observed at C:N of 31:1 and C:P of 428:1, peaked 20 days earlier than in previous studies using untreated lignocellulosic feedstock. Interestingly, the highest hydrolytic activities and solids removal rates were observed at high nitrogen contents; however, the conditions (pH > 8.0) inhibited methanogenesis.

  • Researchpp 4252-4267Zhang, L., and Chen, K. (2016). "Effects of pH and suspended matter on the physico-chemical properties of black liquor from alkali-oxygen pulping of rice straw," BioRes. 11(2), 4252-4267.AbstractArticlePDF

    Black liquor (BL) can be regarded as the energy and alkali resource of the pulping mill. In this work, the effects of the characteristics of black liquor derived from the alkali-oxygen pulping of rice straw were studied. Through analyses of the chemical and physical properties, especially the thermodynamics properties, which depend on suspended matter and alkalinity, it was shown that the removal of the suspended matter from the black liquor could effectively improve its thermodynamic properties, particularly in making its solids content reach up to more than 56% at the turning point of its viscosity. Moreover, sodium salt played an important role in the presence of macromolecules and silica in the BL. When the BL was adjusted to pH = 11 with NaOH, the filtered BL had the lowest silica content, the highest volumetric isothermal expansivity (VIE), was more susceptibility to thermal cracking, and was more suitable for processing for alkali recovery.

  • Researchpp 4268-4280Zhang, H., Li, S., Xu, L., Sun, J., Li, J. (2016). "Kinetic study of the decomposition of cellulose to 5-hydroxymethylfurfural in ionic liquid," BioRes. 11(2), 4268-4280.AbstractArticlePDF

    The kinetics of cellulose decomposition in ionic liquid was investigated using microcrystalline cellulose as a raw material. Curve fitting of cellulose degradation kinetic data was carried out by MATLAB. Experimental results demonstrated that the cellulose decomposition rate constant, k1, was less than the constant for glucose decomposition to 5-hydroxymethylfurfural (5-HMF), k2, in the ionic liquid system, gaining a larger gap with increasing temperature. Results indicated that cellulose degradation is a slow reaction compared with glucose decomposition, which controls the speed of the overall reaction steps. CrCl3 increased the rate constant of cellulose and glucose degradation to almost the same degree, thus achieving simultaneous conversion of cellulose, glucose, and 5-HMF. Compared with other reaction systems, the ionic liquid system considerably reduced activation energy. Regression analysis of kinetic data indicated that the catalytic decomposition reactions of cellulose, glucose, and 5-HMF are all first-order reactions.

  • Researchpp 4281-4294Zhang, H., Zhang, Z., and Liu, K. (2016). "Regenerated lignocellulose beads prepared with wheat straw," BioRes. 11(2), 4281-4294.AbstractArticlePDF

    The conversion of lignocellulosic biomass into fine chemicals and polymers has been gaining attention recently. Regenerated lignocellulose beads (RLBs) were prepared by an emulsification/precipitation technique, using wheat straw as a raw material and [Bmim]Cl as a solvent. The morphology and properties of the obtained beads were characterized. The RLBs were perfectly spherical, with a porous microstructure, and had a huge specific surface area (142.4 m2/g). Their components were similar to that of wheat straw; however some chemical and crystal changes of these components occurred during the preparation process. Eighty percent of the beads were in the size range between 24.4 to 149.6 μm, and the mean particle size was 84.7 μm. Furthermore, the beads possessed good thermostability in the temperature range between ambient temperature and 200 °C. This work demonstrated the feasibility of the production of RLBs using lignocellulosic biomass and provided a new direction for high-valued utilization of lignocellulosic agricultural residues.

  • Researchpp 4295-4305Teoh, Y. P., and Ooi, Z. X. (2016). "Evaluation of unstructured kinetic models for the production of bioethanol from banana and pineapple wastes," BioRes. 11(2), 4295-4305.AbstractArticlePDF

    Bioethanol is a renewable energy source, and its production from agricultural wastes, such as banana and pineapple peels, is an economical approach. Enzymatic hydrolysis experiments were performed using a simultaneous saccharification and co-fermentation (SSCF) method. Banana and pineapple wastes inoculated with Aspergillus terreus and Kluyveromyces marxianus produced the maximum ethanol concentrations of 0.35 g/L and 0.27 g/L, respectively. Furthermore, logistic unstructured and incorporated models described well the growth of microorganism, product formation, and substrate utilization during SSCF system with high R2 and low RMSD.

  • Researchpp 4306-4318Ang, A., Ashaari, Z., Bakar, E. S., and Ibrahim, N. A. (2016). "Synthesis and thermal stability of glyoxalated alkali lignin-polyvinylpyrrolidone resins," BioRes. 11(2), 4306-4318.AbstractArticlePDF

    Natural, renewable, and non-toxic lignin-based resin was synthesized through copolymerization with monomeric N-vinyl-2-pyrrolidone (VP) in the presence of benzoyl peroxide (BPO) as the free radical initiator. Glyoxalated lignin was used as the feedstock. The mechanism of copolymerization between the glyoxalated alkali lignin and VP monomer was determined through Fourier-transform infrared spectroscopy (FT-IR). The optimum amount of VP monomer used and the reflux time required in the synthesis process were determined through thermogravimetric analysis (TGA). In the presence of BPO, copolymerization between glyoxalated alkali lignin and VP monomer was accomplished via the formation of ether linkages in a condensation reaction at pH 7.0. More ether linkages were formed with higher amounts of VP monomer and longer reflux times. The addition of VP monomer into glyoxalated alkali lignin increased its thermal stability. FT-IR and TGA indicated that 0.012 moles of VP monomer and an 8-h reflux time were optimum conditions for the synthesis of glyoxalated alkali lignin-polyvinylpyrrolidone resins.

  • Researchpp 4319-4331Jin, E., and Chung, Y. J. (2016). "Combustion characteristics of wood panels treated with phosphorus-nitrogen additives," BioRes. 11(2), 4319-4331.AbstractArticlePDF

    The combustion characteristics were evaluated for wood samples either untreated or treated with a piperazine-N-N´-bis(methylenephosphonic acid) flame retardant. Combustion properties were investigated using a cone calorimeter (ISO 5660-1 2002). The time to ignition of samples treated with the chemical additive was delayed by 193%, 124%, and 61% for maple, ash, and cypress, respectively, compared with the untreated samples. Compared with the untreated sample, the PHRR value was reduced by 20% for t-ash and by 2.6% for cypress, whereas it was increased by 0.28% for t-maple. The time of PHRR for the treated sample was shifted to 1605 s (698%), 470 s (45%), and 340 s (32%) for cypress, ash, and maple, respectively, compared with the untreated samples. The reduced PHRR value and postponed time to PHRR indicated that combustion was suppressed by the thicker char layer. The mean CO yield of t-ash and t-cypress was increased by 2.9% and 27%, respectively, compared with the untreated sample, but t-maple was reduced by 46% compared with maple. The mean CO2 yield of t-maple, t-ash, and t-cypress was decreased by 4%, 13%, and 37%, respectively, compared with the untreated sample. The combustion properties of treated wood were inhibited more than those of untreated wood.

  • Researchpp 4332-4341Zeng, X., Luo, J., Hu, J., Li, J., Gao, Q., and Li, L. (2016). "Aging resistance properties of poplar plywood bonded by soy protein-based adhesive," BioRes. 11(2), 4332-4341.AbstractArticlePDF

    The aging resistance properties of poplar plywood prepared with soy protein-based adhesives were investigated. The shear strength of soybean meal/bisphenol epoxy resin (SM/EP) adhesive increased by 197.5% (surface layer) to 1.19 MPa and 153.5% (core layer) to 1.09 MPa compared to soybean meal (SM) adhesive. Wet-dry cycles of 25 ± 3 °C, 63 ± 2 °C, and 95 ± 2 °C accelerated the aging of poplar plywood with soy protein-based adhesive. After eight 25 ± 3 °C wet-dry cycles, the shear strength of plywood bonded with SM/EP adhesive was reduced to 0.88 MPa (surface layer) and 0.71 MPa (core layer). Furthermore, the shear strength of SM adhesive gradually decreased to 0 (surface and core layer) after six and five 25 ± 3 °C wet-dry cycles. The shear strength of SM/EP adhesives was reduced to 0.96 MPa and 0.79 MPa (surface and core layer) after eight 63 ± 2 °C wet-dry cycles, and 0.53 MPa and 0.27 MPa (surface and core layer) after eight 95 ± 2 °C wet-dry cycles. Vertical density profiles indicated that the decrease of shear strength could be attributed to several factors: The small molecules were dissolved, the molecular chains of the adhesives were hydrolyzed by water, and the interior and thermal stress destroyed the bonding structure.

  • Researchpp 4342-4352Xu, Y., Kuang, Y., Salminen, P., and Chen, G. (2016). "The influence of nano-fibrillated cellulose as a coating component in paper coating," BioRes. 11(2), 4342-4352.AbstractArticlePDF

    This work investigates nano-fibrillated cellulose (NFC) as a component in mineral pigment paper coating. In this work, bleached Eucalyptus pulp was pretreated by TEMPO (2,2,6,6-tetramethyl-1-piperdinyloxy)-mediated oxidation. The oxidized pulp was then isolated to obtain NFC by sonication. Aqueous coating colors consisting of calcium carbonate, clay, carboxylated butadiene-styrene latex, additives, and NFC were prepared. The rheology of the coating colors and the surface properties of paper coated with NFC containing coating colors were determined. The rheological properties allowed NFC to be used in small amounts under laboratory conditions. Nano-fibrillated cellulose was found to improve the surface strength and smoothness of the coated paper. The water resistance of coated paper, on the other hand, decreased because of the hydrophilicity of NFC.

  • Researchpp 4353-4368Ni, H., Ren, S., Fang, G., and Ma, Y. (2016). "Determination of alkali lignin solubility parameters by inverse gas chromatography and Hansen solubility parameters," BioRes. 11(2), 4353-4368.AbstractArticlePDF

    The physicochemical properties of alkali lignin are crucial to its potential applications and recyclability, as it is one of the most important natural polymer materials. In this study, the solubility parameter (δ) of alkali lignin was determined using Hansen solubility parameters (HSP) theory and inverse gas chromatography (IGC). The δ of alkali lignin was determined by the IGC technique. Solute retention volumes (Vg0) of 6 solutes were determined using alkali lignin as the stationary phase. From 50 to 110 ºC, the δ of alkali lignin varied from 24.47 to 24.15 MPa1/2. Hansen solubility spheres were plotted using the data from the literature for the interactions of alkali lignin with 36 solutes to determine the three dimensional solubility parameter of alkali lignin at 25 to 100 ºC. These determined δ values were consistent with those calculated experimentally via IGC. Acetone was a moderate solvent for the alkali lignin.

  • Researchpp 4369-4378Xu, B., Yang, Z. Y., Liu, S., and Chao, J. (2016). "Comparative research between rhizome and culm of Phyllostachys pubescens based on thermal analysis," BioRes. 11(2), 4369-4378.AbstractArticlePDF

    A systematic study was conducted on P. pubescens by analyzing thermal characteristics of its rhizome and culm (1.5 m) at different ages, using various analyses such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetry (TG). For both the rhizome and culm of P. pubescens, the relative crystallinity (Cr) of cellulose increased and then appreciably decreased with increasing age, but the rhizome contained about 10% less Cr than culm. However, the glass transition temperature (Tg) of culm (268.8 to 273.8 °C) was higher than in the rhizome (213.9 to 219.4 °C). The extrapolated initial decomposition temperature (Te) of 1-, 3-, and 5-year-old rhizome were 263.7 °C, 266.1 °C, and 263.9 °C, respectively; the Te of culms of the same age were 289.7 °C, 282.8 °C, and 283.4 °C, respectively. Variance analysis showed no significant differences in the Te of either rhizome or culm of different ages. Taking the chemical characteristics into consideration, it was concluded that the rhizome has a stable composition and good heat resistance.

  • Researchpp 4379-4391Baker, P. W., Winters, A., and Hale, M. D. C. (2016). "Biodegradation of different genotypes of Miscanthus by wood rot fungi," BioRes. 11(2), 4379-4391.AbstractArticlePDF

    Miscanthus, which is comprised of several different genotypes, is an important high-biomass crop with applications in the biofuel industry and in the formation of biocomposite materials. The overall composition of Miscanthus can be altered via degradation with wood rot fungi. The starting composition revealed that the cellulose content of Miscanthus x giganteus was higher than that in Miscanthus sacchariflorus and that the lignin contents were similar in both genotypes. Of the wood rot fungi, only Lentinus edodes appeared to have completely colonized M. sacchariflorus and showed significant degradation. In contrast, all of the brown rot fungi showed partial colonization of both Miscanthus genotypes and had little effect on the fibrous composition. Cellulose degradation by some white rot fungi increased with cellulose content whereas cellulose degradation by other fungi was independent of cellulose content. All of the white rot fungi showed similar rates of lignin degradation, except for Pleurotus ostreatus, which was higher on M. sacchariflorus. The effect of the moisture contents of Miscanthus on cellulose and lignin decomposition by Phlebiopsis gigantea SPLog6 and Coniophora puteana 11E was also investigated. These results revealed subtle differences in the growth of white rot fungi on different Miscanthus genotypes.

  • Researchpp 4392-4401Cheng, X. F., Qian, H., Zhang, S. W., Zhang, Z. S., He, Y., and Ma, M. G. (2016). "Preparation and characterization of cellulose-CaCO3 composites by an eco-friendly microwave-assisted route in a mixed solution of ionic liquid and ethylene glycol," BioRes. 11(2), 4392-4401.AbstractArticlePDF

    The purpose of this study was to investigate a popular reinforcing agent in the papermaking industry through a quick, environmentally friendly, microwave-assisted method. The preparation and characterization of cellulose-CaCO3 composites through this route, in a mixed solution of an ionic liquid and ethylene glycol, can occur within a 10-min timeframe. The chemical compounds, calcium acetate and sodium carbonate, were used as reactants for the as-obtained CaCO3 crystals. A NaOH-urea aqueous solution was used to treat the cellulose and prepare cellulose-CaCO3 composites. It was discovered that the addition of ionic liquids favors the preparation of cellulose-CaCO3 composites.

  • Researchpp 4402-4414Porankiewicz, B., Tylman, M., Wieczorek, D., Bocho-Janiszewska, A., Klimaszewska, E., and Wieloch, G. (2016). "The combustive heat of thirteen deciduous wood species," BioRes. 11(2), 4402-4414.AbstractArticlePDF

    The heat of combustion relative to the mass, Qm, was evaluated for 13 deciduous wood species, ranging from low to high density. The maximum and minimum values for Qm ranged, respectively, from 19.01 kJ∙g-1 (Sd = 7 J∙g-1) to 21.66 kJ∙g-1 (Sd = 6 J∙g-1) for Populus tremula and Alnus glutinosa wood. The average value of the Qm for all wood specimens evaluated in the present study was 19.93 kJ∙g-1 (Sd = 706 J∙g-1), which is 1.6% higher than the value reported in the literature (Krzysik 1975). A high correlation, R = 0.99, was observed between the volumetric heat of combustion, Qv, and wood density, D0. No correlation was discovered among Qm, D0, the ash content in the wood, ac, as well as the content of the following elements in the ash: calcium (Ca), potassium (K), magnesium (Mg), sodium (Na), silica (Si), aluminum (Al), iron (Fe), copper (Cu), manganese (Mn), sulfur (S), and phosphorus (P).

  • Researchpp 4415-4431Luo, Y., Guda, V. K., Steele, P. H., and Wan, H. (2016). "Hydrodeoxygenation of oxidized and hydrotreated bio-oils to hydrocarbons in fixed-bed continuous reactor," BioRes. 11(2), 4415-4431.AbstractArticlePDF

    The physical and chemical properties of raw bio-oil, two oxidized bio-oils, and hydrotreated bio-oil were compared before and after catalytic hydrodeoxygenation using sulfided CoMo/γ-Al2O3 catalyst. Following continuous hydrodeoxygenation, the organic liquid products from treated bio-oils and raw bio-oil were compared for higher heating value, oxygen content, water content, and viscosity. In addition, Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry were employed to identify functional groups and chemical species, respectively. Fresh and spent catalysts were characterized by nitrogen adsorption-desorption for surface area and pore properties. The degree of coking of the spent catalysts was analyzed by thermogravimetric analysis. Hydrodeoxygenation of hydrotreated bio-oil (HB) gave the longest reaction time on stream of 780 min, the least coking amount of 20 wt%, and the highest hydrocarbon selectivity of 70% up to 720 min of reaction time on stream. Moreover, organic liquid products from HB showed relatively stable properties such as low oxygen content, water content, and viscosity over a longer period of reaction time on stream.

  • Researchpp 4432-4445Rout, A. K., Kar, J., Jesthi, D. K., and Sutar, A. K. (2016). "Effect of surface treatment on the physical, chemical, and mechanical properties of palm tree leaf stalk fibers," BioRes. 11(2), 4432-4445.AbstractArticlePDF

    A new class of leaf stalk fibers of the palm tree were extracted and treated with a 5% NaOH solution for 1 h, 2 h, 6 h, and 12 h. The treated fibers were then characterized by tensile strength testing, chemical analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and solid state NMR. The tensile strength of the fibers was improved with an alkali treatment, and the 6 h treatment resulted in the maximum fiber strength. The maximum cellulose content was present in the 6 h-treated fibers; cellulose content was reduced with a longer treatment (12 h). Similarly, SEM, FTIR, XRD, and NMR confirmed the removal of hemicelluloses from the raw fiber surface and the formation of new hydrogen bonds between the cellulose fibril chains with respect to the duration of the treatment. The 5% alkali treatment also improved the fiber density from 0.85 gm/cc (raw fiber) to 1.05 gm/cc, 1.13 gm/cc, 1.17 gm/cc, and 1.25 gm/cc after the 1 h, 2 h, 6 h, and 12 h treatments, respectively.

  • Researchpp 4446-4458Takata, E., Nge, T. T., Takahashi, S., Ohashi, Y., and Yamada, T. (2016). "Acidic solvolysis of softwood in recycled polyethylene glycol system," BioRes. 11(2), 4446-4458.AbstractArticlePDF

    The acidic solvolysis of lignocellulose using a glycol solvent such as polyethylene glycol (PEG) is a promising process for separating its components and producing a valuable lignin product that can be used as thermoplastic and fusible materials. To decrease operational costs, a glycol solvent that is used as a solvolysis reagent must be recovered and reused. In the present study, PEG was recovered by the removal of water by evaporation from the supernatant after glycol lignin production by acidic solvolysis of Japanese cedar using PEG with an average molecular weight of 200 (PEG200). The recovered PEG200 worked as a solvolysis reagent and produced glycol lignin with appropriate yield. The thermomechanical analysis of glycol lignin from the fresh and recovered PEG200 systems exhibited two inflection points, which were assigned to a glass transition point (Tg) and a thermal softening point (Ts). The Ts of the glycol lignin from the recovered PEG200 system was higher than that from the fresh PEG200 system. These results suggest that the glycol lignin from the recovered PEG200 system had high thermostability as well as high thermal fusibility.

  • Researchpp 4459-4471Ni, L., Zhang, X., Liu, H., Sun, Z., Song, G., Yang, L., and Jiang, Z. (2016). "Manufacture and mechanical properties of glued bamboo laminates," BioRes. 11(2), 4459-4471.AbstractArticlePDF

    Moso bamboo (Phyllostachys pubescens Mazei ex H. de Lebaie), one of the most commonly used species in China, is a strong and stiff material. In this paper, the manufacturing process for glued bamboo laminate (GBL) is presented. The mechanical properties of GBL (compression strength, bending, tension, and shearing) were tested. Results indicated that the mechanical properties of GBL were significantly different for different grades of GBL, but that the performance of GBL was controllable. The edge butt joint greatly influenced the tensile performance, but the butt joint had little impact on the bending performance. In addition, the good mechanical performance of GBL is sufficient for engineering members, making it a potentially useful bamboo product for engineering.

  • Researchpp 4472-4484Zhang, W., Chen, J., Bekele, L. D., Liu, Y., Duns, G. J., and Jin, L. (2016). "Physical and mechanical properties of modified wheat straw-filled polyethylene composites," BioRes. 11(2), 4472-4484.AbstractArticlePDF

    This study investigates the effect of modified wheat straw on the physical and mechanical properties of modified wheat straw/high-density polyethylene (MWS/HDPE) straw-plastic composites. Wheat straw fibers with particle sizes in the range of 0.25 to 0.50 mm were modified with caprolactam (CPL). A Fourier transform infrared spectroscopy (FT-IR) analysis of MWS showed that when the CPL level was 5%, the intensity of the hydroxyl (O–H) and carbonyl (C–O) absorption peaks noticeably decreased, indicating a corresponding decrease in the polarity of the fibers. A physical analysis of the wheat straw fibers indicated that after the modification, the characteristics of the fibers were closer to those of the HDPE polymer matrix, thus contributing to good compatibility and dispersion of the straw fibers within the matrix. The composites of the high-density polyethylene with modified wheat straw particles were successfully synthesized using the melt blend method. The prepared composites were characterized using scanning electron microscopy (SEM), and their mechanical properties were investigated. The MWS/HDPE composites showed superior mechanical properties because of a greater compatibility of MWS with HDPE. The modified WS fibers function as “biological steel,” reinforcing the HDPE to produce bio-composites.

  • Researchpp 4485-4511Abu Bakar, A. H., Koay, Y. S., Ching, Y. C., Abdullah, L. C., Choong, T. S. Y., Alkhatib, M., Mobarekeh, M. N., and Mohd Zahri, N. A. (2016). "Removal of fluoride using quaternized palm kernel shell as adsorbents: Equilibrium isotherms and kinetics studies," BioRes. 11(2), 4485-4511.AbstractArticlePDF

    Palm kernel shell (PKS) core fibers, an agricultural waste, were chemically modified using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHMAC) as a quaternizing agent. The potential of quaternized palm kernel shell (QPKS) as an adsorbent for fluoride in an aqueous solution was then studied. The quaternized palm kernel shell (QPKS) core fibers were characterized using Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope (SEM). The effect of various factors on the fluoride sequestration was also investigated. The results showed that with an increase in the adsorbent amount and contact time, the efficiency of fluoride removal was improved. The maximum fluoride uptake was obtained at pH 3 and a contact time of 4 h. The adsorption behavior was further investigated using equilibrium isotherms and kinetics studies. The results from these studies fit well into Freundlich, Redlich-Peterson, and Sips isotherm’s with a coefficient of determination (R2) of 0.9716. The maximum fluoride removal was 63%. For kinetics studies, the pseudo-second order was the best fit for fluoride, with an R2 of 0.999. These results suggest that QPKS has the potential to serve as a low-cost adsorbent for fluoride removal from aqueous solutions.

  • Researchpp 4512-4525Shen, H., Cao, J., Sun, W., and Peng, Y. (2016). "Influence of post-extraction on photostability of thermally modified Scots pine wood during artificial weathering," BioRes. 11(2), 4512-4525.AbstractArticlePDF

    The photo-stabilizing effect of post-extraction was evaluated for thermally modified wood. Extracted and non-extracted thermally modified Scots pine (Pinus sylvestris L.) samples were exposed in a xenon weather-ometer for 1008 h, and the surface color and chemical changes were characterized using a chroma meter, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The results showed that: (1) the weight losses of thermally modified wood were higher than those of unmodified wood after extraction due to the leaching of some low molecular weight compounds that were generated during thermal modification; (2) the photodegradation of thermally modified wood during weathering was hindered by the presence of extractives; and (3) the color change during weathering was a little more severe in sapwood than in heartwood because more extractives were present in heartwood.

  • Researchpp 4526-4535Widyorini, R., Nugraha, P. A., Rahman, M. Z. A., and Prayitno, T. A. (2016). "Bonding ability of a new adhesive composed of citric acid-sucrose for particleboard," BioRes. 11(2), 4526-4535.AbstractArticlePDF

    Citric acid is a potential binding agent for composite products that has three carboxyl groups that can be ester linked with the hydroxyl groups found in wood. The addition of sucrose provides hydroxyl groups and increases the amount of ester groups. This research investigated the bonding ability of a new adhesive composed of citric acid-sucrose for teak particleboard. Citric acid and sucrose were dissolved in water under various ratios, and the concentration of the solution was adjusted to 59 to 60 wt%.This adhesive solution was sprayed onto the particles at 10% resin content based on the weight of air-dried particles. Each mixture was then hot pressed at 180 and 200 °C for 10 min. The physical and mechanical properties of the particleboards were tested, and the results showed that increasing the pressing temperature affected the dimensional stability. However, increasing of citric acid in adhesive composition improved the dimensional stability and mechanical properties of the particleboards. The optimum properties of the board were achieved at a pressing temperature of 200 °C and addition of only 10% citric acid. The results also indicated that the peak intensity of C=O group increased with the addition of citric acid and increasing pressing temperature, indicating that ester linkage occurred. However, the addition of sucrose did not greatly affect the peak intensity of C=O group.

  • Researchpp 4536-4549Jiang, Z., Miao, J., Yu, Y., and Zhang, L. (2016). "Effective preparation of bamboo cellulose fibers in quaternary ammonium/DMSO solvent," BioRes. 11(2), 4536-4549.AbstractArticlePDF

    A novel, efficient, and direct blend of solvents, tetrabutylammonium acetate/dimethyl sulfoxide (TBAA/DMSO), was used for the dissolution and regeneration of bamboo pulp. Regenerated fibers were successfully prepared by a wet spinning process. The bamboo pulp without any pretreatment was readily soluble in the solvent under mild conditions. The dissolution process was observed using a confocal laser scanning microscope (CLSM). Rheological properties of the cellulose solutions at various concentrations were investigated. The regenerated fibers prepared by coagulation in ethanol were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and an electronic tensile tester. The SEM images showed that the regenerated fibers possessed a smooth surface and circular cross-section, and the XRD and FT-IR results revealed that the fibers exhibited a cellulose II structure. The thermostability and mechanical properties of the fibers was also investigated.

  • Researchpp 4550-4563Siddhu, M. A. H., Li, J., Zhang, R., Liu, J., Ji, J., He, Y., Chen, C., and Liu, G. (2016). "Potential of black liquor of potassium hydroxide to pretreat corn stover for biomethane production," BioRes. 11(2), 4550-4563.AbstractArticlePDF

    Reducing the pretreatment cost of lignocellulosic biomass by utilizing alkali to alter its recalcitrant nature is an effective method for biofuel production. In this experiment, 1.5% KOH solution and its black liquor (spent liquor of KOH) (BL) were applied to pretreat corn stover (CS) at a temperature of 20 °C to enhance the digestibility for anaerobic digestion (AD). Results showed no significant difference in weighted average methane content on the basis of experimental methane and biogas yields between BL-treated and original KOH-treated CS after AD. The BL process significantly increased the overall methane yield by 52.4% compared with untreated CS (135.2 mL/gVS), whereas no significant difference between the overall methane yields of 1.5% KOH-treated and BL-treated CS was observed. In addition, the BL process significantly saved water and KOH consumption, by 56.2% and 57.4%, respectively, compared with the 1.5% KOH pretreatment. Overall methane production was well explained by the modified Gompertz model. The physiochemical changes to CS after BL pretreatment were confirmed by SEM, FTIR, and XRD analyses. Our findings collectively suggest that recycling and reuse of KOH black liquor might be an efficient method for lignocellulosic biomass treatment and have the capability to reduce input costs in future AD processes.

  • Researchpp 4564-4578He, X., Wang, D., Zhang, Y., and Tang, Y. (2016). "Manufacturing technology and parameter optimization for composite board from corn stalk rinds," BioRes. 11(2), 4564-4578.AbstractArticlePDF

    To improve the bonding strength between adhesive and enhance the performance of composite board made from corn stalk rinds, a method for preparing three-layer composite boards was proposed. Accordingly, corn stalk rinds with the epidermis removed, were used as the core layer, while crushed aggregates from the epidermis were used as the surface layer of the composite board. Single-factor and orthogonal experiments were conducted to analyze the effects of the sampling height of corn stalk rinds, the surface layer proportions, and the hot-pressing temperature and time on the physico-mechanical properties of composite board. The resulting composite board from corn stalk rinds showed enhanced properties, except for the internal bond strength (P < 0.01). The physical properties of the composite board were significantly improved (P < 0.01) by removing the crushed aggregates of the epidermis, forming a single layer of composite board. The optimal parameters were as follows: the sampling height below the ear part of the corn stalk rinds; 12% surface layers; 150 °C hot-pressing temperature; and 6 min time. Under these conditions, the physico-mechanical properties of the composite board met the requirement level for particleboard. This research supports the use of corn stalk rinds as composite boards.

  • Researchpp 4579-4592Cai, L., Fu, Q., Niu, M., Wu, Z., and Xie, Y. (2016). "Effect of chlorinated paraffin nanoemulsion on the microstructure and water repellency of ultra-low density fiberboard," BioRes. 11(2), 4579-4592.AbstractArticlePDF

    This work describes a water repellent ultra-low density fiberboard (ULDF) prepared by chlorinated paraffin nanoemulsion (CPNE). Compared with the untreated ULDF, the contact angle of ULDF treated with 150 mL of CPNE increased from 40° to 134°, while its apparent surface free energy decreased from 24.19 mN/m to 10.06 mN/m. Moreover, the water absorbance of ULDF treated with CPNE decreased from 88.2% to 24% in the first hour. The improved hydrophobicity and hygroscopicity of ULDF was supported by the presence of a film on the surface of fibers, as observed by environmental scanning electron microscopy. The occurrence of chlorine and the chemical structure changes in ULDF before and after CPNE treatment were also confirmed by X-ray photoelectron spectroscopy analysis and Fourier transform infrared spectroscopy respectively. This ULDF with enhanced water repellency is a promising insulation material.

  • Researchpp 4593-4604Guan, C., Zhang, H., Hunt, J. F., Zhou, L., and Feng, D. (2016). "Measurement of dynamic viscoelasticity of full-size wood composite panels using a vibration testing method," BioRes. 11(2), 4593-4604.AbstractArticlePDF

    The dynamic viscoelasticity of full-size wood composite panels (WCPs) under the free-free vibrational state were determined by a vibration testing method. Vibration detection tests were performed on 194 pieces of three types of full-size WCPs (particleboard, medium density fiberboard, and plywood (PW)). The dynamic viscoelasticity from smaller specimens cut from the panels was measured using a cantilever beam vibration test apparatus, and the two data sets were compared. A strong linear relationship was discovered between the dynamic viscoelasticity values measured by the vibration detection test and the cantilever beam vibration test. The storage modulus values of the panels were far higher than their loss modulus values, and PW panels had the smallest value of loss modulus. For the panels tested, density had a good linear impact on storage modulus. In comparison with density, logarithmic decrement had a greater linear impact on loss modulus. This study demonstrated that the vibration test method is a valid approach for determining the dynamic viscoelasticity of full-size WCPs.

  • Researchpp 4605-4620Lu, X., and Hu, Y. (2016). "Layer-by-layer deposition of TiO2 nanoparticles in the wood surface and its superhydrophobic performance," BioRes. 11(2), 4605-4620.AbstractArticlePDF

    A hydrophilic wood surface was transformed to become superhydrophobic by layer-by-layer (LbL) assembly of polyelectrolyte/titanium dioxide (TiO2) nanoparticles multilayers and subsequent hydrophobic modification with 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane (POTS). The chemical composition of the wood samples before and after treatment was characterized by energy dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). These analyses showed that a high-surface-roughness film of TiO2 nanoparticles deposited by LbL became combined on the wood surface with a low-surface-energy thin layer of POTS. The microstructure and the hydrophobicity of the wood samples were analyzed by scanning electron microscope (SEM) and contact angle measurements, respectively. The morphology and the values of water contact angle (WCA) demonstrated that the reaction pH and number of self-assembled layers were the main factors affecting hydrophobic wood samples. After assembly with 5 or more multilayers, the wood surface exhibited excellent superhydrophobicity with the highest WCA of 161°.

  • Researchpp 4621-4632Lehto, J. T., Louhelainen, J., Pakkanen, H., Malkavaara, P., Kłosińska, T., Drożdżek, M., and Alén, R. (2016). "Chemometric study on alkaline pre-treatments of wood chips prior to pulping," BioRes. 11(2), 4621-4632.AbstractArticlePDF

    Alkaline pre-treatments were performed for the production of organics-containing effluents from silver/white birch (Betula pendula/pubescens) and Scots pine (Pinus sylvestris) chips prior to chemical pulping. Pre-treatment conditions were varied with respect to time (from 30 min to 120 min), temperature (130 °C and 150 °C), and alkali charge (1, 2, 3, 4, 6, and 8% of NaOH on oven-dried wood). The analytical data (total content, weight average molar mass, and molar mass distribution) on dissolved lignin were subjected to principal component analysis to examine the relationship between molar mass and molar mass distributions in lignin removed from different wood species under varying alkaline pre-treatment conditions. Using this method, differences between the wood species and effects of the various pre-treatment process variables (i.e., time, temperature, and alkali charge) were determined.

  • Researchpp 4633-4644Buck, D., Wang, X., Hagman, O., and Gustafsson, A. (2016). "Bending properties of cross laminated timber (CLT) with a 45° alternating layer configuration," BioRes. 11(2), 4633-4644.AbstractArticlePDF

    Bending tests were conducted with cross laminated timber (CLT) panels made using an alternating layer arrangement. Boards of Norway spruce were used to manufacture five-layer panels on an industrial CLT production line. In total, 20 samples were tested, consisting of two CLT configurations with 10 samples of each type: transverse layers at 45° and the conventional 90° arrangement. Sample dimensions were 95 mm × 590 mm × 2000 mm. The CLT panels were tested by four point bending in the main load-carrying direction in a flatwise panel layup. The results indicated that bending strength increased by 35% for elements assembled with 45° layers in comparison with 90° layers. Improved mechanical load bearing panel properties could lead to a larger span length with less material.

  • Researchpp 4645-4662Chen, Y. W., Lee, H. V., and Abd Hamid, S. B. (2016). "A response surface methodology study: Effects of trivalent Cr3+ metal ion-catalyzed hydrolysis on nanocellulose crystallinity and yield," BioRes. 11(2), 4645-4662.AbstractArticlePDF

    The preparation of nanocellulose via Cr(NO3)3-assisted sulfuric acid hydrolysis was optimized using response surface methodology (RSM). The experiment was performed using a five-level, four-factor central composite design coupled with RSM in order to optimize nanocellulose crystallinity and product yield. Four factors were evaluated for the preparation of nanocellulose: (1) reaction temperature, (2) hydrolysis time, (3) Cr(NO3­)3 concentration, and (4) H2SO4 concentration. Based on the RSM model, the maximum yield and highest crystallinity of nanocellulose was obtained under hydrolysis conditions of 82.2 °C, 0.22 M Cr(NO3)3, and 0.80 M H2SO4 with 1 h of reaction. Furthermore, the physicochemical properties of the obtained nanocellulose were examined, revealing that the amorphous regions were successfully hydrolyzed, while the crystalline region remained unaltered. Morphology analysis also showed that the nanocellulose was an interconnected web-like network. Thus, both H2SO4 and Cr(III) metal salt concentration were important factors that influenced the nanocellulose yield and crystallinity index.

  • Researchpp 4663-4676Pánek, M., and Reinprecht, L. (2016). "Effect of the number of UV-protective coats on the color stability and surface defects of painted black locust and Norway spruce woods subjected to natural weathering," BioRes. 11(2), 4663-4676.AbstractArticlePDF

    This paper utilized 12 coating systems, based on an acrylate and a hydrophobic polymer, with the addition of light pigments, nano-sized polyvalent metal (AsS-chelate complex) for ultraviolet protection, and iodopropynyl butylcarbamate fungicide. This study deals with the impact of the number of coats on the color stability and the surface defects of painted black locust (Robinia pseudoacacia L.) and Norway spruce (Picea abies Karst L.) woods after up to three years of natural weathering, at a slope of 45°. The best coating system was created from three coats, which consisted of two pigmented acrylates (PerlColor) and one transparent hydrophobic water-repellent (AquaStop). The total color change, ΔE*, of the weathered surfaces was approximately two times lower when the application involved a pigmented coating system compared with a transparent one. The color stability of the surfaces and their resistance to defects was better when the coating system was applied to black locust wood compared with spruce wood. Smoother surfaces of wood before painting resulted in a higher resistance against cracking and other defects caused by natural weathering; however, the effect of the initial wood roughness on the color stability of painted woods during natural weathering was usually negligible.

  • Researchpp 4677-4687Podlena, M., and Borůvka, V. (2016). "Stiffness coefficients of mortise and tenon joints used on wooden window profiles," BioRes. 11(2), 4677-4687.AbstractArticlePDF

    Samples of corner joints of wooden rectangular windows, with widths of 78 and 92 mm, were used to determine the stiffness of tenon and mortise joints. Two series of samples were loaded statically in the angular plane of compression and tension, so that the bending moment could be derived. The objective of the experiment was to determine the existing correlations between the stiffness in maximum strength and the stiffness in the elastic area for both types of tests. After strength tests were carried out, the annual ring width of the samples was measured to determine whether this factor affects the stiffness of the joints. The results showed that there was a relatively strong correlation between the stiffness in the elastic area and the maximum load. A two-factor analysis of variance confirmed that the type of load did not affect the stiffness of the joint, but the type of joint (width) does significantly affect the stiffness. Therefore, the width of annual rings was positively correlated with the stiffness of the joints.

  • Researchpp 4688-4704Wallmeier, M., Hauptmann, M., and Majschak, J. P. (2016). "The occurrence of rupture in deep-drawing of paperboard," BioRes. 11(2), 4688-4704.AbstractArticlePDF

    The production of paperboard packaging components in fast-running machines requires reliability of the production process. Boundaries for the process parameters and constraints for the geometry of the tools require investigation to determine dependable configurations. This paper aimed to investigate the relationships between process parameters, tool geometry, and the occurrence of rupture in the deep-drawing process of paperboard. Different types of ruptures in various phases of the process were distinguished and linked to their specific cause. An extensive experimental investigation with multiple variables of influence was conducted. A logistic regression model was used to describe the experimental data and was statistically validated. The blankholder force was found to be the most influential parameter. Interactions between the parameters blankholder force, punch velocity, and punch diameter were recognized. A high punch velocity can reduce the probability of rupture when the punch diameter is adjusted.

  • Researchpp 4705-4717Chang, F. C., Chan, K. K., and Chang, C. Y. (2016). "The effect of processing parameters on formation of lignosulfonate fibers produced using electrospinning technology," BioRes. 11(2), 4705-4717.AbstractArticlePDF

    Lignosulfonate fibers were produced using electrospinning technology, a method of manufacturing fibrous materials using polymeric solutions, by adding traces of polyethylene oxide to lignosulfonate solutions. Continuous and uniform fibers were obtained under appropriate processing conditions. Solution concentration, applied voltage, flow rate, and syringe-to-collector distance all had effects on fiber formation and diameter. Certain interactive effects among these processing parameters were also observed. Solution concentration was the most significant parameter influencing the diameters of the resulting lignosulfonate fibers. Higher solution concentrations resulted in greater fiber diameters. A broader distribution of fibers was observed as the solution concentration increased. Applied voltage, flow rate, and syringe-to-collector distance had moderate effects on the fiber diameters, and needle gauge had a minor impact on the fiber diameters.

  • Researchpp 4718-4726Lee, J. Y., Kim, E. H., and Sung, Y. J. (2016). "Improvement in the retention and strength of paper made from white-grade wastepaper," BioRes. 11(2), 4718-4726.AbstractArticlePDF

    White ledger is white-grade recycled pulp that replaces the bleached kraft pulp (BKP) that typically forms the top ply of duplex boards. However, sheets made from white ledger are inferior in strength compared with those made from virgin pulp. Therefore, it is necessary to select a proper additive in order to overcome the disadvantages of using white ledger. In this study, the physical properties of white ledger used at a mill that produced duplex boards were analyzed. The effect of cationic polyacrylamides (C-PAMs) with different charge densities and molecular weights on first-pass retention and paper strengths was simultaneously measured. White ledger contains fiber fines and filler fines, which reduced the strength of paper made from white ledger compared with paper made with BKP. This indicates that the improvement of first-pass retention and paper strength is important when the amount of white ledger increases in the top ply of a duplex board. The charge density of C-PAM, which acts as a retention aid, is more important than its molecular weight in terms of improving the first-pass retention and paper strength of white ledger. The charge density of C-PAM must be high enough to catch anionic fine particles.

  • Researchpp 4727-4744Fleming, M. B., Decker, S. R., and Bedinger, P. A. (2016). "Investigating the role of extensin proteins in poplar biomass recalcitrance," BioRes. 11(2), 4727-4744.AbstractArticlePDF

    The biological conversion of cellulosic biomass to biofuel is hindered by cell wall recalcitrance, which can limit the ability of cellulases to access and break down cellulose. The purpose of this study was to investigate whether hydroxyproline-rich cell wall proteins (extensins) are present in poplar stem biomass, and whether these proteins may contribute to recalcitrance. Three classical extensin genes were identified in Populus trichocarpa through bioinformatic analysis of poplar genome sequences, with the following proposed names: PtEXTENSIN1 (Potri.001G019700); PtEXTENSIN2 (Potri.001G020100); PtEXTENSIN3 (Potri.018G050100). Tissue print immunoblots localized the extensin proteins in poplar stems to regions near the vascular cambium. Different thermochemical pretreatments reduced but did not eliminate hydroxyproline (Hyp, a proxy for extensins) from the biomass. Protease treatment of liquid hot water-pretreated poplar biomass reduced Hyp content by a further 16% and increased subsequent glucose yield by 20%. These data suggest that extensins may contribute to recalcitrance in pretreated poplar biomass, and that incorporating protease treatment into pretreatment protocols could result in a small but significant increase in the yield of fermentable glucose.

  • Researchpp 4745-4757Li, J., Zhou, P., Lv, X., Xiao, W., Gong, Y., Lin, J., and Liu, Z. (2016). "Use of sugarcane bagasse with different particle sizes to determine the relationship between physical properties and enzymatic hydrolysis," BioRes. 11(2), 4745-4757.AbstractArticlePDF

    The supramolecular structures of a substrate, such as crystallinity, specific surface area, average pore size, and cellulase adsorption capacity, etc., affect the enzymatic hydrolysis of a lignocellulosic biomass. It is unclear which of these factors is most important for efficient hydrolysis. To eliminate the influence of the hemicellulose content and the lignin, sugarcane bagasse samples with the same cellulose, hemicellulose, and lignin content but with different particle sizes were used as substrates to investigate the relationship between physical properties and enzymatic conversion efficiency. When the content of hemicellulose and lignin was not significantly different, the decrease in the crystallinity index (CrI) and the increase in the specific surface area (SSA), cellulase adsorption, average pore size, and the cellulase adsorption per SSA could give rise to higher enzymatic convertibility. The effects of the CrI and the average pore size were more pronounced than the effects of the SSA, the cellulase adsorption capacity, and the cellulase adsorption per SSA. According to the developed formula, the CrI was more influential than the average pore size under the specific conditions.

  • Researchpp 4758-4769Kiziltas, E. E., Yang, H. S., Kiziltas, A., Boran, S., Ozen. E., and Gardner, D. J. (2016). "Thermal analysis of polyamide 6 composites filled by natural fiber blend," BioRes. 11(2), 4758-4769.AbstractArticlePDF

    This study describes changes in the viscoelastic and thermal properties of composites made with various percentages (up to 20 wt.%) of a natural fiber blend (a mixture of flax, kenaf, and hemp fibers) and polyamide 6 (PA 6). According to the differential scanning calorimetry (DSC) analyses, the incorporation of natural fibers produced minor changes in the glass transition (Tg), melting (Tm), and crystallization temperature (Tc) of the PA 6 composites. Because of the reinforcing effect of natural fibers, the storage modulus (E’) from dynamic mechanical thermal analysis (DMTA) increased as the natural fiber content increased. The E’ values at room temperature and Tg were 3960 MPa and 1800 MPa, respectively, with the incorporation 20 wt.% fiber, which were 68% and 193% higher than the E’ value of neat PA 6. As the natural fiber content increased, the thermal stability of the composites decreased, and thermogravimetric analysis (TGA) showed that the onset temperature of rapid thermal degradation decreased from around 440 (neat PA 6) to 420 °C (20 wt.% natural fiber blend). The addition of 20 wt.% single type fibers showed comparable DSC and TG results to the incorporation of 20 wt.% natural fiber blends.

  • Researchpp 4770-4780Kiziltas, E. E., Kiziltas, A., and Gardner, D. J. (2016). "Rheological and mechanical properties of ultra-fine cellulose-filled thermoplastic epoxy composites," BioRes. 11(2), 4770-4780.AbstractArticlePDF

    Thermoplastic epoxy resin (TPER)-based composites containing different amounts of ultra-fine cellulose (UFC) were prepared via melt compounding and injection molding. The effect of UFC loading on the mechanical properties and dynamic rheological behavior of the UFC-filled TPER composites was analyzed. The UFC-filled composites displayed higher complex viscosities than those of the neat TPER composites, especially at low frequencies. The elastic modulus of the 20 wt.% UFC-filled composite was up to 6- and 2-fold higher than that of TPER at 0.1 and 100 Hz, respectively. The loss factor decreased over the entire frequency range with the incorporation of UFC. The tensile modulus of elasticity (TMOE) of neat TPER was 3.13 GPa, and it increased as a function of UFC loading. The neat TPER exhibited the lowest flexural strength (108.1 MPa), and the flexural strength increased by 14% with the incorporation of 20 wt.% UFC. The results of the TMOE and the flexural modulus of elasticity (FMOE) were in agreement with rheological data on complex viscosity, elastic modulus, and viscous modulus. Ultra-fine cellulose-filled TPER composites may provide special capabilities for automotive applications and may also meet requirements for end-of-life vehicle (ELV) directives.

  • Researchpp 4781-4793Sakagami, H., Tokunaga, A., Fujimoto, N., Koga, S., Kobayashi, I., and Momohara, I. (2016). "Effects of drying temperature for Cryptomeria japonica on the permeability of wood preservative. I: The permeability of dried logs," BioRes. 11(2), 4781-4793.AbstractArticlePDF

    Wood preservative treatments are indispensable for wood used in severe environmental conditions. Decay occurs in preservative-treated woods due to the poor impregnation of sapwood; this problem has recently gained attention for Cryptomeria japonica kiln-dried logs. To clarify the causes of this phenomenon, the influence of drying temperature on the penetration of preservative into sapwood logs was investigated. Sapwood samples taken from logs dried at 20 °C to 120 °C were impregnated with copper azole (CuAz). The bordered pits of these samples were observed by scanning electron microscopy (SEM). These results revealed that CuAz absorption decreased with increased drying temperature. The CuAz penetration was deepest for the samples dried at 20 °C. The occurrence of neutral-position bordered pits tended to decrease with increasing drying temperature. These results indicated that there is a strong relationship between the drying temperature and the appearance of bordered pits. Furthermore, the preservative permeability decreased with increasing drying temperature. This result implies that one factor restraining fluid permeability is the aspiration of bordered pits.

  • Researchpp 4794-4807Carmo, J. F., Miranda, I., Quilhó, T., Carvalho, A. M., Carmo, F. H. D. J., Latorraca, J. V. F., and Pereira, H. (2016). "Bark characterisation of the Brazilian hardwood Goupia glabra in terms of its valorisation," BioRes. 11(2), 4794-4807.AbstractArticlePDF

    The bark of Goupia glabra trees grown in a native forest area in the Amazon region of Brazil was anatomically and chemically characterised for potential use as a chemical source for bio-refineries. The bark is silvery-grey to reddish-grey, with a scaly rhytidome composed of 2 to 3 periderms with a small phellem content. The phloem has abundant sieve tube members and a conspicuous presence of sclerified nodules of fiber-sclereids or sclereids; no fibers were observed. The bark had the following average composition (dry mass): 5.2% ash, 24.6% total extractives, 1.1% suberin, and 43.8% total lignin. The polysaccharide composition showed a high ratio of xylan hemicelluloses to cellulose. The ethanol-water bark extract showed high antioxidant capacity. The chemical characterisation of different granulometric fractions showed that extractives were present preferentially in the finest fractions, particularly with enrichment in ethanol solution.

  • Researchpp 4808-4820Hajdúchová, I., Sedliačiková, M., Halaj, D., Krištofík, P., Musa, H., and Viszlai, I. (2016). "The Slovakian forest-based sector in the context of globalization," BioRes. 11(2), 4808-4820.AbstractArticlePDF

    This paper investigates the impact of the global economy on the forest-based sector in Slovakia in the early years of the 21st century. Indicators such as gross domestic product, production value of forestry-wood sectors, net exports, foreign direct investments, and the ratio indices of foreign direct investment to GDP in industrial production and foreign direct investment to production value were used to analyze this sector in the context of globalization. Multiple regression analysis was used to determine the factors that significantly affect the development of the forest-based sector and to shed light on how globalization impacts the analyzed sector. The results showed that the forest-based sector had a minor impact of the Slovak economy with less than 5% share on the whole GDP. Using multiple regression analysis it was found that globalization factors such as foreign direct investment and net export did not have a significant influence (p > 0.44175) on the forest-based sector during the investigated period. Nevertheless, the highest globalization indicators were detected by the pulp and paper industry ( = 2.72; 29.14) and the furniture manufacturing ( = 1.60; 27.57). The highest variability of FDI was identified in the forest sector (vx = 72.38%; 67.32%) by influence of zero FDI in the last three years and in the wood industry (vx = 38.90%; 38.51%).

  • Researchpp 4821-4838Wang, G, Zhang, J., Shao, J., Jiang, Y., Gao, B., Zhao, D., Liu, D., Wang, H., Liu, Z., and Jiao, K. (2016). "Experiments and kinetic modeling for the oxidative decomposition of herbaceous and wooden residues," BioRes. 11(2), 4821-4838.AbstractArticlePDF

    The thermal characteristics of Paulownia sawdust (PS), bamboo sawdust (BS), rice lemma (RL), and corncob (CC) in an oxidizing atmosphere were investigated using thermogravimetric analysis. The results indicated that the reaction of biomass oxidative decomposition took place in two main phases: devolatilization and char oxidation. Among various types of biomass, BS was found to possess the highest oxidative decomposition reactivity followed by PS, CC, and RL. Additionally, an increase in heating rate led to a significant improvement of the reactivity. The kinetic modeling of the oxidation reaction with the direct fitting method using the DRPM model showed a satisfied match with the experimental data, and the activation energy of biomass during the devolatilization process was higher than that of the char oxidation process. The activation energy of devolatilization was in the range of 80.7 to 133.8 kJ/mol, while that value of char oxidation fluctuated between 41.7 and 67.5 kJ/mol. In addition, with an increase in the heating rate, a marked compensation effect between the activation energy and pre-exponential factors was observed.

  • Researchpp 4839-4849Qiao, Z., Gu, J., Lv, S., Cao, J., Tan, H., and Zhang, Y. (2016). "Preparation and properties of normal temperature cured starch-based wood adhesive," BioRes. 11(2), 4839-4849.AbstractArticlePDF

    A normal temperature cured starch-based wood adhesive was prepared using dry method esterification and polyisocyanate prepolymer crosslinking. The effects of esterification and crosslinking on the properties of corn starch adhesive were investigated. The esterified starch and adhesive were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), dielectric analysis (DEA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that maleic anhydride (MAH) esterified starch was obtained using dry method esterification. After esterification, the crystal type of starch did not change, but the crystallinity of starch decreased. The distribution of adhesive at the bonding interface was improved after esterification. The prepolymer improved the thermal stability of the adhesive, and the optimal addition of prepolymer was 10%.

  • Researchpp 4850-4864Hadi, S., Hosseinihashemi, S. K., Jahan Latibari, A., and Salem, M. Z. M. (2016). "Effects of acid copper chromate preservative and hydrothermal treatment on the dimensional stability, hardness, and decay resistance of poplar wood," BioRes. 11(2), 4850-4864.AbstractArticlePDF

    The effects of acid copper chromate (ACC) and hydrothermal treatments were determined relative to the hardness, decay resistance, and dimensional stability of poplar wood. Test specimens, prepared from poplar wood (Populus nigra L.), were first heat-treated under saturated steam in a digester and then impregnated with ACC solution and by a long-term (21 days) dipping technique to reach complete saturation. Impregnated specimens were exposed to white-rot fungus (Trametes versicolor) for 14 weeks, using the Kolle flask method. The weight loss and Brinell hardness were determined after impregnation, thermal treatment, and exposure to T. versicolor. The combination of thermal treatment and ACC preservative on the poplar wood showed improved hardness and decay resistance properties of wood, depending on the treatment time and temperature. The highest weight loss (37.78%) was observed for control specimens, and the lowest (3.03%) occurred in 1% ACC-treated specimens. The highest Brinell hardness on a tangential surface was observed in 1% ACC-treated specimens (6.45 kN), and the lowest was noted in the specimens heat-treated at 130 °C and 180 min (0.52 kN).

  • Researchpp 4865-4884Birnin-Yauri, A. U., Ibrahim, N. A., Zainuddin, N., Abdan, K., Then, Y. Y., and Chieng, B. W. (2016). "Enhancement of the mechanical properties and dimensional stability of oil palm empty fruit bunch-kenaf core and oil palm mesocarp-kenaf core hybrid fiber-reinforced poly(lactic acid) biocomposites by borax decahydrate modification of fibers," BioRes. 11(2), 4865-4884.AbstractArticlePDF

    The surfaces of kenaf core fiber (KCF), oil palmempty fruit bunch fiber (EFBF), and oil palm mesocarp fiber (OPMF), were chemically modified using 5 wt.% aqueous sodium tetraborate decahydrate (borax) solution to enhance their hybrid fiber interface bonding with a polylactic acid (PLA) matrix. The untreated fibers (KCF, EFBF, and OPMF) and treated fibers (BXKCF, BXEFBF, and BXOPMF), were examined using chemical analysis, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The treatment caused minimal removal of lignin and significant elimination of hemicellulose and waxy substances. The treated and untreated KCF (5%), as a secondary fiber, was randomly mixed, respectively, with treated and untreated EFBF and OPMF (55%), melt-blended with PLA (40%), and subsequently compression-molded to form hybrid fiber-PLA biocomposites. The resulting composite is aimed to exhibit improvements in its mechanical properties and dimensional stability. The optimum results for tensile and flexural properties, as well as water uptake and thickness swelling, were observed for the borax-treated fibers in comparison with the untreated fibers. The BXEFBF-BXKCF-PLA biocomposites exhibited the best results. This work demonstrated that aqueous borax modification of natural fibers could offer a possible option to the most common mercerization method.

  • Researchpp 4885-4898Cao, X., Zhu, B., Chen, T., Zhang, X., and Dong, H. (2016). "Recombinant protein A immobilized on cross-linked cellulose microspheres for immunoglobulin G adsorption from human plasma," BioRes. 11(2), 4885-4898.AbstractArticlePDF

    Cross-linked cellulose microspheres (CL-CMs) were successfully prepared using an inverse crosslinking suspension method from a cellulose solution with sodium hydroxide/urea aqueous solution as a solvent and epichlorohydrin as the crosslinker. The effects of epichlorohydrin content on the appearance and dispersity, average pore volume, moisture content, and wet real density of CL-CMs were studied. The microspheres presented a good spherical shape and porous surface structure. After activation with NaIO4, the recombinant protein A was immobilized onto the surface of CL-CMs to form an immunoadsorbent. Adsorbents containing various amounts of protein A were applied to adsorb immunoglobulin G (IgG) from human plasma. The maximum IgG adsorption capacities with static adsorption and dynamic adsorption were 23 and 13 mg, respectively, per gram of CL-CMs carrying 6.8 mg of recombinant protein A. Therefore, CL-CMs immobilized with recombinant protein A have great potential for application in the field of blood purification.

  • Researchpp 4899-4920Gao, Y., Yu, B., Xin, S., Mi, T., Chen, Y., Yuan, Q., Yang, L., and Li, P. (2016). "Use of extreme vertices method for analysis of how proportional composition affects component interactions and product distribution during hydrothermal treatment," BioRes. 11(2), 4899-4920.AbstractArticlePDF

    The interaction among three biomass components (hemicellulose, cellulose, and lignin) in an autoclave was studied based on the extreme vertices of a constrained region that had a significant effect on the distribution and characteristics of the products. The mathematical model of the three components was established according to the yield distribution. Based on the model, the biomass components and the hydrothermal characteristics of biomass were predicted. Subsequently, the contents of the main biomass components were analyzed, thus eliminating the complicated testing process and providing a convenient and reliable calculation tool for determining the three biomass components. The gaseous products showed that products from cellulose hydrolysis promoted hemicellulose hydrolysis and generated large amounts of CO2. The lignin content, as well as the low cellulose and hemicellulose contents, inhibited the acids and ketones in light oil. In addition, the interaction among cellulose, hemicellulose, and lignin inhibited the production of acids in heavy oil and promoted phenolic synthesis. A series of hydrolysis product reactions such as polymerization and condensation were increased to produce a char at a high degree of aromatization by the interaction among the three components.

  • Researchpp 4921-4934Zhu, L., Liu, Y., and Liu, Z. (2016). "Effect of high-temperature heat treatment on the acoustic-vibration performance of Picea jezoensis," BioRes. 11(2), 4921-4934.AbstractPDF
    The crystallinity and acoustic-vibration parameters of Picea jezoensis, including specific Young’s modulus (E/ρ)coefficient of sound-radiation resistance (R), sound resistance (ω), and the ratio of Young’s modulus to the dynamic stiffness modulus (E/G), before and after heat treatment were measured and characterized. Conditions for the heat treatment included N2 as the protection gas and temperatures of 170 °C, 190 °C, and 210 °C with holding times of 2 h, 3 h, and 4 h. The results showed that specific Young’s modulus, the coefficient of sound-radiation resistance, and the ratio of Young’s modulus to the dynamic stiffness modulus ncreased, whereas sound resistance decreased, thereby improving the acoustic performance of the wood. The maximum increments were 5.7% for specific Young’s modulus (210 °C, 3 h), 8.8% for the coefficient of sound-radiation resistance (210 °C, 3 h), and 13.8% for the ratio of Young’s modulus to the dynamic stiffness modulus (210 °C, 4 h). Conversely, the maximum decrease in sound resistance was 5.6% (170 °C, 2 h). The crystallinity of heat-treated samples universally increased, and the maximum reached 60.67% (210 °C, 4 h), which was 9.9% higher than that of the control group. Moreover, the sound resistance decreased within increasing crystallinity growth, indicating that these two parameters were negatively correlated. Overall, the acoustic-vibration performance of P. jezoensis was improved through heat treatment, with the best vibration performance obtained at 210 °C with a holding time of 4 h.
  • Researchpp 4935-4946Shalbafan, A., Benthien, J. T., and Lerche, H. (2016). "Biological characterization of panels manufactured from recycled particleboards using different adhesives," BioRes. 11(2), 4935-4946.AbstractPDF
    Transforming waste or recycled materials into value-added products is of high priority today. Wood plastic composites (WPCs) show high potential for the use of recycled materials in making durable composites. The applicability of WPC panels produced from recycled materials (ultralight foam core particleboards) for exterior building application was tested using wood-destroying basidiomycetes. The results showed that the panels were fully resistant against Coniophora puteana (Cp) and Gloeophyllum trabeum (Gt), but not very resistant against Pleurotus ostreatus (Po). The decay susceptibility index of Po-exposed specimens showed that the polystyrene-bonded (PS) samples were more resistant than solid beech wood samples that were used as references, followed by melamine-urea formaldehyde-bonded samples. A comparison with the reference samples also showed that the panel density had a significant influence on the panel’s resistance against basidiomycetes. The higher the panel density, the more resistance will be achieved in the panel.
  • Researchpp 4947-4963Zhang, X., Li, J., Zhang, Y., Cai, W., and Liu, H. (2016). "Data-driven method for pulp properties estimation in stock preparation," BioRes. 11(2), 4947-4963.AbstractPDF
    Pulp properties are key factors to assessing the performance of a refining process, evaluating operational conditions, and optimizing the process of stock preparation. This paper presents a data-driven approach to estimate the beating degree and wet weight of pulp after refining using case-based reasoning (CBR). Historical data generated in a refining process at a paper mill was used to evaluate the proposed model. The root mean square error (RMSE) and coefficient of variance of the root mean square error (CV-RMSE) of the beating degree estimation results in CBR were 1.30 and 4.32%, respectively, and the RMSE and CV-RMSE of the wet weight were 0.50 and 19.09%, respectively. The results of beating degree prediction were satisfactory, and the results of wet weight were also acceptable. To test the performance of CBR model, support vector machine algorithm (SVM) were employed to verify the effectiveness and accuracy. The RMSE and CV-RMSE of the beating degree estimation results in SVM were 1.20 and 4.02%, respectively, and the RMSE and CV-RMSE of the wet weight were 0.44 and 16.73%, respectively. As a result, the proposed model was as accurate as the SVM method.
  • Researchpp 4964-4989Žlahtič, M., and Humar, M. (2016). "Influence of artificial and natural weathering on the hydrophobicity and surface properties of wood," BioRes. 11(2), 4964-4989.AbstractPDF
    The use of wood in outdoor, above-ground applications is increasing in Europe. To further increase wood usage, more information related to service life and maintenance costs must be provided. Water exclusion efficacy (WEE) is one of the most important factors influencing service life and strongly correlates to wood moisture dynamics, surface properties, and hydrophobicity (WEE as a whole). WEE can be improved with modifications and hydrophobic treatments. The aim of this study was to elucidate which wood surface properties affect WEE and to note changes over time caused by artificial or natural aging. Wood samples of oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica) were used to investigate this phenomenon. The moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. In total, 17 materials were prepared. After treatment, four different aging procedures were applied. Before and after aging, Fourier transform infrared spectra, colour, and contact angle were determined. The analysis of untreated wood based materials indicated that durability and hydrophobicity are related. Of all the treatments, wax performed the best and retained high hydrophobicity even after the most severe aging method (outdoor exposure).
  • Researchpp 4990-5002Kiaei, M., Samariha, A., and Farsi, M. (2016). "Effects of montmorillonite clay on mechanical and morphological properties of papers made with cationic starch and neutral sulfite semichemical or old corrugated container pulps," BioRes. 11(2), 4990-5002.AbstractArticlePDF

    The impact of montmorillonite (nanoclay) addition on the mechanical and morphological properties of paper made from neutral sulfite semichemical (NSSC) and old corrugated container (OCC) pulps was evaluated in systems utilizing cationic starch for dry-strength. The nanoclay amount was considered at five levels, and cationic starch was applied at a 1% level. In OCC pulp, by increasing the nanoclay up to 4%, the tensile index and corrugating medium test (CMT) were increased; however, there was a decrease when the nanoclay was increased to 8%. By increasing the nanoclay to 2%, the tear and burst indexes and ring crush test (RCT) increased, but there was a reduction when the nanoclay was increased to 8%. Average air resistance tended to increase as the nanoclay was increased to 8%. In the case of NSSC pulp, by increasing the nanoclay amount from 0 to 8%, the average tensile, tear, and burst indexes decreased, while the air resistance increased. The CMT amount increased with increasing nanoclay content to 2%, but a reduction was seen for other levels. The RCT exhibited an increase with increasing nanoclay up to 4%, after which it decreased. Results suggest that the proportion of nanoclay added with cationic starch needs to be optimized, depending on furnish conditions.

  • Researchpp 5003-5012Ratnasingam, J., Ramasamy, G., and Ioras, F. (2016). "The influence of log felling season on the extent of discoloration in rubberwood sawn timber during the kiln drying process," BioRes. 11(2), 5003-5012.AbstractArticlePDF

    This study investigated the effects of felling season on the discoloration of rubberwood sawn timber during conventional kiln drying. The samples were collected throughout the year 2015 to monitor the variation of free sugars and starch content in the rubberwood logs. Two batches of logs, one from the rainy season and the other from the dry season, were felled and sawn for experimentation. The findings showed that discoloration was more prominent in sawn timber obtained from logs felled during the dry season. The amount of free sugars and starch in the logs had a strong influence on the extent of discoloration in the rubberwood sawn timber during the kiln drying process. A higher amount of free sugars and starch in the logs felled during the dry season increased the incidence of blue stain on these logs. The results of this study conclusively showed that discoloration in rubberwood can be minimized by the choice of log felling season and the use of an appropriate drying technique, which will inevitably improve the aesthetic appeal of the wood.

  • Researchpp 5013-5032Ishmael, U. C., Shah, S. R., Palliah, J. V., Asras, M. F. F., Ahmad, S. S., and Ayodele Bamidele, V. (2016). "Statistical modeling and optimization of enzymatic pretreatment of empty fruit bunches with laccase enzyme," BioRes. 11(2), 5013-5032.AbstractArticlePDF

    Laccase enzyme was used as a pretreatment agent to delignify empty fruit bunches (EFB) for sugar production. The degree of delignification of the biomass was assessed directly by the percentage of pre-pretreatment weight loss (%) after pretreatment and indirectly by the amount of total sugar produced after saccharification of the pretreated biomass with cellulase enzymes. Process parameters such as pretreatment time, temperature, enzyme concentration, substrate concentration, pH, and substrate size were studied using a one-factor-at-a-time (OFAT) analysis. The combined effect of temperature and pH on the pretreatment was studied using the face-centered central composite design (FCCCD) of response surface methodology (RSM). The optimized conditions for EFB pretreatment using laccase enzyme were achieved as follows: sample size, 2 mm; temperature, 25 °C; time, 4 h; substrate concentration, 5% (w/v); pH 5; and enzyme concentration, 20 IU/g of EFB. Although higher pretreatment was achieved with substrates of 1 mm size and at a temperature of 35 °C, these conditions were not considered energetically sustainable because of the need for energy during milling for sample size reduction and energy for temperature maintenance at 35 °C.

  • Researchpp 5033-5049Plazonic, I., Bates, I., and Barbaric-Mikocevic , Z. (2016). "The effect of straw fibers in printing papers on dot reproduction attributes, as realized by UV inkjet technology," BioRes. 11(2), 5033-5049.AbstractArticlePDF

    Paper performance qualities strongly depend on the origin of cellulose fibers. Awareness of environmental issues and sustainable development has led to the increase in the use of recycled printing papers. Recovered fibers are often used as a substitute for virgin wood fibers in the production of certain types of papers. As recovered fibers cannot provide the same quality level of paper products as virgin wood fibers, alternative sources of virgin cellulose fibers need to be identified. The aim of this research was to analyze the printability of laboratory papers made of different contents of straw pulp. Therefore, the printing papers were formed using straw pulp of three different cereal species (wheat, barley, and triticale) and mixing them with recycled newsprint in different weight ratios. The printability of these laboratory papers was analyzed by classifying dot reproduction quality based on four dot reproduction attributes. Printed dot reproduction greatly affects the quality of reproduction in graphic products, as dots are the most important element in multi-color reproduction of texts and images. It was confirmed that laboratory papers containing straw pulp provide the same or even better dot reproduction quality than laboratory control papers formed only of recycled newsprint.

  • Researchpp 5050-5063Wu, Z., Chen, T., Niu, M., Cai, L., Xie, Y., and Wang, X. (2016). "Effect of boron-zinc-aluminum-silicium compounds on the fire performance of ultra-low density fiberboards," BioRes. 11(2), 5050-5063.AbstractPDF
    B-Zn-Si-Al compounds are modified Si-Al compounds made of sodium silicate, zinc sulfate, borax, and aluminum sulfate. They act as a fire retardant during the preparation of ultra-low density fiberboards (ULDFs). An orthogonal experiment was used to optimize the contents of the four compounds according to the limiting oxygen index. Fourier transform infrared spectroscopy was employed to preliminarily analyze the chemical structure of the compounds. Additionally, a cone calorimeter was used to assess the fire performance of the ULDFs. The results suggested that the optimized solution was made of 27.0 mL of sodium silicate solution, 27.0 mL of aluminum sulfate solution, 3.0 g of zinc sulfate, and 6.5 g of borax, resulting in an oxygen index of 29.5%. The bond Al-O-B was detected at 1397 and 796 cm-1. The Si-O-Zn bonds were detected at 867 cm-1. The heat release rate, total heat release, and total smoke release decreased and the mass residual ratio increased in the sample using the optimal conditions from the orthogonal array design. It was concluded that B-Zn-Si-Al compounds effectively protect fibers from fire.
  • Researchpp 5064-5074Ratnasingam, J., Ramasamy, G., Ioras, F., and Thanasegaran, G. (2016). "Potential co-generation of electrical energy from mill waste: A case study of the Malaysian furniture manufacturing industry," BioRes. 11(2), 5064-5074.AbstractArticlePDF

    Furniture manufacturing in Malaysia is an established industry driven primarily by the availability of raw materials and labor. However, the industry suffers from the low-recovery rate of its materials, as it produces a substantial amount of waste during the manufacturing process. Although smaller waste fragments, or off-cuts, are recovered for other purposes, the splinters, shavings, and coarse dust have little economic value and are often discarded. Because wood is a well-established source of bioenergy, this study investigated the potential use of mill waste from the furniture-manufacturing industry for electrical energy generation. Waste from the rubberwood, bamboo, and rattan furniture industries was evaluated for its potential electrical energy generation, and the amount was compared with the electrical energy that was consumed by the furniture industry. The study also compared the emission of greenhouse gases from the combustion of these waste materials against fossil fuels used to generate electricity to assess its potential in terms of the environmental benefits. In conclusion, such mill waste could be utilized as substitute for fossil fuel to generate energy in the furniture industry.

  • Researchpp 5075-5082Zhang, Y., Zhang, W., and Lu, W. (2016). "Effect on tensile strength of wood-based carbon fiber impregnated by boron," BioRes. 11(2), 5075-5082.AbstractPDF
    Wood-based carbon fiber derived from liquefied wood has the disadvantages of low mechanical strength and unstable performance. To improve its mechanical properties, wood-based carbon fiber precursors were impregnated with 5 wt.% and 8 wt.% boric acid solutions for 1 h and then carbonized at 900 °C for 1 h. The effect of boron content on fiber tensile strength and microstructure was investigated through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The tensile strength of wood-based carbon fibers impregnated with 5 wt.% boric acid reached 0.468 GPa, an increase of 44.89% compared with the untreated samples. In addition, the amount of graphitoidal crystal and the degree of graphitization increased with the boric impregnation. Furthermore, boron in the form of a boron-carbon solid solution in the graphene layer of carbon fibers effectively improved the tensile strength of wood-based carbon fibers.
  • Researchpp 5083-5099Chen, Y., Su, C., Yuan, Q., Zhan, M., Yang, B., and Xia, J. (2016). "Electromagnetic shielding performance of nickel plated expanded graphite/wood fiber composite," BioRes. 11(2), 5083-5099.AbstractPDF
    To develop a wood-based electromagnetic shielding composite, in-situ electroless plating was used to plate nickel onto the surface of expanded graphite (EG) to obtain nickel-plated EG (Ni-EG), and the Ni-EG was mixed with wood fiber to manufacture the composite. The optimal plating formula was as follows: 20 g/L NiSO4·6H2O as the main salt, 60 g/L N2H4·H2O as the reducing agent, 50 g/L Na3C6H5O7·2H2O as the complexing agent, 40 g/L CH3COONa·H2O as the buffering agent, pH value 11, and a temperature of 90 °C. These conditions yielded the highest quality of nickel coating (3.57 g). As EG concentration increased from 2 to 10 g/L, the percentage of the Ni-EG in the composite was 60%, the thickness of the composite was 2 mm, the density was 0.9 g/cm3, the magnetic properties and resistivity of the Ni-EG decreased from 29.5 to 5.57 emu/g and 80.2 to 10.7 mΩ·cm, respectively, and the electromagnetic shielding effectiveness (SE) and the reflectivity of the composite increased from 55 to 60 dB and −3.6 to -1.8 dB, respectively. Consequently, the introduction of nickel is suitable for improving the absorbing performance of Ni-EG/wood fiber composites, leading to better SE in a broad frequency range.
  • Researchpp 5100-5112Zhang, X., Li, M., Zhong, L., Peng, X., and Sun, R. (2016). "Microwave-assisted extraction of polysaccharides from bamboo (Phyllostachys acuta) leaves and their antioxidant activity," BioRes. 11(2), 5100-5112.AbstractPDF
    Polysaccharides were isolated from Phyllostachys acuta leaves by microwave-assisted extraction under various temperatures and time. The obtained polysaccharides were characterized by acid hydrolysis, the Folin-Ciocalteu method, and Fourier transform infrared spectroscopy (FTIR). The major monosaccharides presented in the extracts were arabinose (258.0 mg/g to 414.5 mg/g), galactose (167.0 mg/g to 289.2 mg/g), and glucose (157.4 mg/g to 246.7 mg/g) along with some mannose, fructose, and xylose. The total phenol yield of the bamboo leaves was 0.31 mg/g to 0.73 mg/g. The FTIR spectra revealed that the polysaccharides mostly consisted of β-glycosidic linkages. For the cytotoxicity, the presence of polysaccharides considerably elevated the multiplication of HepG2 cells and showed no growth inhibition for the samples. For the antioxidant activities, the polysaccharides exhibited excellent abilities both in the diphenyl picrylhydrazyl radical potential (DPPH) assay and ferric reducing antioxidant potential (FRAP) assay. The results suggest that bamboo leaf polysaccharides have great potential to be applied in the food, healthcare, and pharmaceutical fields.
  • Researchpp 5113-5123Yu, X., Zhu, X., Lin, X., Li, F., and Gu, Z. (2016). "Effects of two-stage controlled pH and temperature vs. one-step process for hemicellulase biosynthesis and feruloyl oligosaccharide fermentation using Aureobasidium pullulans," BioRes. 11(2), 5113-5123.AbstractPDF
    A two-stage, pH- and temperature-controlled wheat bran fermentation method using Aureobasidium pullulans was investigated for feruloyl oligosaccharides (FOs) production and the activities of xylanase, xylosidase, and ferulic acid esterase (FAE). A. pullulans secreted xylanase, xylosidase, and FAE at high levels in the initial pH of 4.0 to 5.0 and a fermentation liquid temperature of 31 °C to 33 °C. FOs production via two-stage fermentation (FOs 2) reached 1123 nmol/L after fermentation for 96 h, by controlling the initial pH at 4.0 and the initial temperature at 33 °C, and then changing the pH to 6.0 and the temperature to 29 °C at the same time at 36 h. This process was 12 h shorter and 219 nmol/L higher than a one-stage fermentation for producing FOs 1. Xylanase, xylosidase, and FAE activities were highly correlated with controlled pH and temperature and FOs biosynthesis rate. Thus, the combination of two-stage controlled pH and temperature could support mass production of FOs.
  • Researchpp 5124-5137Inoue, H., Fujimoto, S., and Sakaki, T. (2016). "Two-step hot-compressed water treatment of Douglas fir for efficient total sugar recovery by enzymatic hydrolysis," BioRes. 11(2), 5124-5137.AbstractPDF
    The non-catalytic hydrothermal pretreatment of softwood is generally less effective for subsequent enzymatic hydrolysis. In this study, the efficacy of hot-compressed water (HCW) treatment of Douglas fir was investigated between 180 °C and 260 °C, allowing solubilization of the cellulose components. The enzymatic digestibility of cellulosic residues increased significantly under HCW conditions > 250 °C, and the enhanced glucan digestibility was closely related to the decomposition of the cellulose component. Combination of the first-stage HCW treatment (220 °C, 5 min) to recover hemicellulosic sugars with the second-stage HCW treatment (260 °C, 5 min) to improve cellulose digestibility gave a total sugar recovery of 56.2% based on the dried raw materials. This yield was 1.4 times higher than that from the one-step HCW-treated sample (260 °C, 5 min). Additionally, an enzymatic hydrolysate from the two-step HCW-treated sample exceeded 90% of the ethanol fermentation yield based on the total sugars present in the hydrolysates. These results suggest the potential of the two-step HCW treatment of softwood as a pretreatment technology for efficient total sugar recovery and ethanol production.
  • Researchpp 5138-5154Shah, S. R., Ishmael, U. C., Palliah, J. V., Asras, M. F. F., and Wan Ahmad, S. S. B. N. (2016). "Optimization of the enzymatic saccharification process of empty fruit bunch pretreated with laccase enzyme," BioRes. 11(2), 5138-5154.AbstractPDF
    The saccharification of laccase-pretreated empty fruit bunch (EFB) was optimized in a lab-scale experiment using one-factor-at-a-time (OFAT) and response surface methodology (RSM). After pretreatment, the degree of delignification was checked by noting the weight loss (%) after pretreatment, and also by the quantity of total sugar produced after saccharification with cellulase enzyme. OFAT studies of saccharification of the pretreated EFB showed that the biomass was best saccharified using cellulase enzyme at the following conditions: enzyme concentration of 30 IU/g of EFB, substrate concentration of 5.0% w/v, 50 °C, saccharification time of 24 h, and pH 5. This combination exhibited the highest yield of total sugar (28% w/w). Although 29% w/w yield was achieved with an enzyme concentration of 40 IU/g of EFB, this increase in yield was not proportional to the increased enzyme concentration and, therefore, was considered insignificant. Statistical analysis of the combined effects of pH and temperature showed that pH had a more significant effect than the temperature on the saccharification process, based on a P < 0.05 significance level. The effect of pH on total sugar production was more significant than the temperature in both linear and quadratic functions. In sum, the saccharification of laccase-pretreated EFB should follow the optimized process conditions achieved in the current study.
  • Researchpp 5155-5168Oberhofnerová, E., Arnetová, K., Holeček, T., Borůvka, V., and Bomba, J. (2016). "Determination of correlation between destructive and nondestructive test methods applied on modified wood exposed to natural weathering," BioRes. 11(2), 5155-5168.AbstractPDF
    The objective of this study was to determine a correlation between the dynamic modulus of elasticity (MOEd) and the static modulus of elasticity (MOEs), and to assess the potential of using nondestructive (NDT) methods as a grading tool for both treated and untreated wood exposed to weathering. In the experiment, test samples made from spruce and oak were exposed for four months to natural weathering. Half of the specimens were treated with a silicon-based nano-protection. The MOEd was determined using acoustic NDT methods–ultrasound transmission (MOEdu) and the vibration methods (MOEdv), while the MOEs was determined by a destructive three-point bending test. The results showed that there was no statistical significance for the influence of the time of exposure and the surface treatment on the modulus of elasticity. The ultrasound method, measured in the longest distance of the sample, had the most significant correlation with the MOEs. The vibration method also reached a similar correlation with the MOEs. The mean values of the MOEdu and MOEdv were higher than the MOEs. The influence of density on the acoustic wave velocity was not confirmed.
  • Researchpp 5169-5180Madhoushi, M. (2016). "Species and mechanical strengths of wood members in a historical timber building in Gorgan (North of Iran)," BioRes. 11(2), 5169-5180.AbstractPDF
    This research introduces one of the most important historic constructions in Gorgan, namely, the House of Bagheri, placing an emphasis on wooden materials, noting that a considerable amount of solid wood was utilized as a structural element of this building. First, anatomical identification of species of wood was performed by the microscopic identification. The mechanical properties of selected old structural members were determined and compared with standard values, as well as visually inspected by an expert carpenter. The results indicated that several domestic hardwoods and one imported softwood had been used, and that old members (~ %36) showed acceptable mechanical strength despite their decayed appearance. The results implied that the visual inspections were very conservative and not reliable for restoration operations.
  • Researchpp 5181-5189Pinkowski, G., Krauss, A., Piernik, M., and Szymański, W. (2016). "Effect of thermal treatment on the surface roughness of scots pine (Pinus sylvestris L.) wood after plane milling" BioRes. 11(2), 5181-5189.AbstractPDF
    The surface roughness in plane milled Scots pine wood that was thermally modified at 190 °C and 220 °C was examined. Indicators of wood surface roughness included the three most commonly applied parameters, arithmetic mean surface roughness (Ra), surface roughness depth (Rz), and total height of the roughness profile (Rt). Roughness was tested separately for earlywood and latewood using two feed speeds of 1 and 5 m/min. The thickness of the milled layer was 1 mm. The effect of all controlled factors, i.e., feed speed, temperature of modification, and place of measurements, on the parameters of surface roughness were statistically significant (P < 0.05). Surface roughness increased with an increase in feed speed, whereas it decreased with an increased modification temperature. Latewood was characteristically lower in roughness than earlywood. The greatest differences in homogenous groups for the determination of the roughness parameters were found in measurements taken on earlywood and latewood, while the smallest differences were recorded for different feed speeds.
  • Researchpp 5190-5203Zhang, H., Li, S., Song, X., Li, P., and Li, J. (2016). "Preparation of 5-(hydroxymethyl)furfural by the catalytic degradation of cellulose in an ionic liquid/organic biphasic system," BioRes. 11(2), 5190-5203.AbstractPDF
    This work has established the optimum reaction conditions in a biphasic system using microcrystalline cellulose as the raw material, an ionic liquid as the solvent, metal chloride as a catalyst, and an organic solvent as the extraction reagent. The optimum reaction conditions were microcrystalline cellulose:ionic liquid - 1:10 (mass ratio), chromium(III) chloride (CrCl3) - 6.8 mol% (based on the glucose unit of cellulose molecule), reaction time - 3 h, temperature - 130 °C, and mass ratio of 1-butyl-3-methyl-imidazolium chloride ([BMIM]Cl) to methylbenzene - 1:4.4]. Under these conditions, the yields of glucose and 5-(hydroxymethyl)furfural (5-HMF) were 27% and 55%, respectively. The solvent [BMIM]Cl could be reused twice. The first recovery rate of [BMIM]Cl was approximately 70.9%. The product 5-HMF was obtained in 64.7% yield, which decreased after the first [BMIM]Cl recycling. The second recovery rate of [BMIM]Cl was 45%. The yield of 5-HMF was 39.6%, which decreased after the second recycling of [BMIM]Cl. In this paper, the energy consumption, operation, reutilization of [BMIM]Cl, and product yields of a one-phase system and a biphasic system were compared. Experimental results demonstrated that the biphasic solvent system was suitable for the degradation of cellulose to glucose and 5-HMF.
  • Researchpp 5204-5214Rafique, N., Tabassum, R., Awan, M. S., Orts, W., and Wong, D. W. S. (2016). "Cloning and expression of Pectobacterium carotovorum endo-polygalacturonase gene in Pichia pastoris for production of oligogalacturonates" BioRes. 11(2), 5204-5214.AbstractPDF
    A bacterial endo-polygalacturonase (endo-PGase) gene from the plant pathogen Pectobacterium carotovorum was cloned into pGAPZαA vector and constitutively expressed in Pichia pastoris. The recombinant endo-PGase secreted by the Pichia clone showed a 1.7 fold increase when the culture medium included glycerol in replacement of glucose as the carbon source. The enzyme had optimum activity at pH 5.5 and 40 °C with stability between pH 5.0 and 8.0 and at temperatures up to 50 °C. The enzyme activity was enhanced by 41% with the addition of 1 mM Co++, and inhibited by Fe++ with a 63% reduction. The mode of the enzyme action showed internal cleavage of α-1,4 glycoside bonds of polygalacturonic acid and citrus peel pectin. Trigalacturonate and hexagalacturonate were the main hydrolysis products, with a yield of 0.44±0.01 and 0.21±0.01 mg released per mg polygalacturonic acid substrate, respectively. This represents the first report of a microbial endo-PGase that produced trimer and hexamer uniquely as the end products of hydrolysis, in contrast to mixtures of mono-, di-, and trigalacturonates commonly observed for the action of fungal enzymes. Pectic oligosaccharides generated from native carbohydrate polymers offer the potential application as building blocks for value-added products.
  • Researchpp 5215-5229Cai, L., Zhuang, B., Hang, D., Wang, W., Niu, M., Xie, Y., Chen, T., and Wang, X. (2016). "Ultra-low density fibreboard with improved fire retardance and thermal stability using a novel fire-resistant adhesive," BioRes. 11(2), 5215-5229.AbstractPDF
    A novel fire-resistant adhesive made from polyvinyl alcohol, urea, phosphoric acid, and starch was demonstrated for use as a binder and fire retardant to produce ultra-low density fibreboard (ULDF) with clear environmental benefits. The results from Fourier transform infrared spectroscopy showed the presence of chemical bonding between fire-resistant adhesives and ULDFs. The limiting oxygen index (LOI), combustion behaviour, and thermal stability were characterized using a LOI text, cone calorimeter, and thermal analyzer, respectively. The results demonstrated that the LOI value of the fire-retardant ULDF can reach up to 34.2 with 300 mL of fire-resistant adhesive. It was established that the additive noticeably reduced the peak of heat release rate, total heat release, and total smoke release of ULDF. Their morphologies after combustion were elucidated using a scanning electron microscope, and a char layer in the condensed phase was observed. Thermal analysis showed that the thermal stability of ULDF improved dramatically and the residual weight increased 4-fold, to 48.32%. Therefore, such ULDFs will be tremendously attractive as renewable, sustainable, and bio-based insulating materials.
  • Researchpp 5230-5241García-Iruela, A., Esteban, J. G., de Palacios, P., García-Fernández, F., de Miguel Torres, A., Vázquez Iriarte, E., and Simón, C. (2016). "Resinous wood of Pinus pinaster Ait.: Physico-mechanical properties," BioRes. 11(2), 5230-5241.AbstractPDF
    Pinus pinaster Aiton is the pine with the largest natural area of distribution in Spain and the species that sustains the country’s resin industry, with an annual average production of 3.2 to 3.5 kg per tree. After trees have been tapped, their wood has a high resin content and is of little use because of machining difficulties. For the first time, resinous wood of this species was characterized to compare its physico-mechanical properties with those of non-resinous wood. Significant differences were found in all the properties studied except modulus of elasticity. The resin produced by tapping decreased swelling, probably by reducing accessibility to the –OH groups and decreasing the available spaces during the capillary condensation phase. Similarly, tapping caused an increase in wood density and therefore in hardness, at the same time improving the mechanical properties.
  • Researchpp 5242-5254Očkajová, A., Kučerka, M., Krišťák, L., Ružiak, I., and Gaff, M. (2016). "Efficiency of sanding belts for beech and oak sanding," BioRes. 11(2), 5242-5254.AbstractPDF
    The effects of wear on the performance of sanding belts were determined for European beech (Fagus sylvatica L.) and English oak (Quercus robur). These measurements are presented as a function of the defined sanding time of 480 min on a manual sanding belt machine. Sanding belt pressure on the piece surface (6600, 10400, 14700, and 18600 Pa), sanding direction (cutting speed vector with reference to wood fibers equal to 0°, 60° and 90°), wood hydrothermal treatment, and sanding belts from various manufacturers were the variables. The sanding belt wear was monitored by means of specific wood removal rate (g/cm2.min) in 20-min intervals by the means of reference samples with size of 50 x 50 x 50 mm, which were sanded for 1 min. The resulting curves for the sanding belts, as well as the statistical models of the wood removal rate, decreased as a function of the sanding time, described by the function y = a + b.e-ct. This work also describes the impact of wood species, optimum pressure, and grinding time on the characteristics to abrasion.
  • Researchpp 5255-5264Jia, X., Wang, M., Yuan, W., Ju, X., and Yang, B. (2016). "The influence of biochar addition on chicken manure composting and associated methane and carbon dioxide emissions," BioRes. 11(2), 5255-5264.AbstractPDF
    The effect of biochar addition and turning frequency was examined relative to biochar-chicken manure co-composting and its associated methane (CH4) and carbon dioxide (CO2) emissions. The results demonstrated that biochar addition was more effective in accelerating the composting process, which was indicated by a 5.2% increase in peak pile temperature and a 148% increase in peak CO2 emission with 20% biochar amended-compost, compared with the control that had no biochar. The compost pH increased and moisture content decreased significantly over the whole course of composting with the biochar amendment. The addition of 20% biochar also resulted in a 54.9% decrease in peak CH4 emission compared with the control. More frequent turning (daily vs. every 3 or 7 days) accelerated the composting process and reduced the CH4 emission.
  • Researchpp 5265-5275Majka, J., Czajkowski, Ł., and Olek, W. (2016). "Effects of cyclic changes in relative humidity on the sorption hysteresis of thermally modified spruce wood," BioRes. 11(2), 5265-5275.AbstractPDF
    Thermal modification of spruce wood (Picea abies L.) was conducted at three different temperatures (160, 200, and 240 °C) and treatment times (1, 3, and 5 h). The cyclic sorption experiments were performed for relative humidity changes of 30 to 85%. The equilibrium moisture content of the thermally modified wood was reduced up to 50% after treatment at 240 °C for 5 h. The sorption isotherms were described with the Guggenheim, Anderson, and De Boer (GAB) model. Cyclic sorption increased the monolayer capacity. Thus, the monolayer sorption was increased, while the multilayer sorption was limited. The dependence of the mass loss, hysteresis loop, and the maximum difference of equilibrium moisture content on the modification temperature and duration was modeled by response surface methodology. There was a very strong correlation between the modification temperature and mass loss, while the relationship between treatment time and mass loss was insignificant. The correlations between the modification parameters and the descriptors of sorption hysteresis were stronger after cyclic sorption. The sorption hysteresis decreased after cyclic sorption. This result was mainly caused by the increase of the monomolecular sorption for the adsorption processes.
  • Researchpp 5276-5284Du, C., Li, H., Li, B., Liu, M., and Zhan, H. (2016). "Characteristics and properties of cellulose nanofibers prepared by TEMPO oxidation of corn husk," BioRes. 11(2), 5276-5284.AbstractPDF
    This paper describes preparation of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidized cellulose nanofibers (TOCNs) from corn husk. The process adopted for this work included alkaline treatment, TEMPO/NaBr/NaClO-mediated oxidation, and homogenization. The morphological investigation of TOCNs was performed using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The chemical composition and structure of the material obtained after each stage of the treatments was characterized through Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. The thermal stability of the samples was investigated by thermogravimetric analysis (TGA). The obtained TOCNs possessed a narrow width, ranging from 8 to 10 nm, and a high aspect ratio (> 300). The crystallinity type of TOCNs was found to be cellulose-Iβ. Compared with the original fibers, the crystallinity of TOCNs gradually increased because of the removal of hemicellulose and lignin, while the thermal stability decreased.
  • Researchpp 5285-5298Chen, C., Wang, W., Cao, J., Qi, Q., and Ma, W. (2016). "Properties of thermally modified southern pine wood pretreated with alkylalkoxysilanes," BioRes. 11(2), 5285-5298.AbstractPDF
    The alkyl-alkoxysilane (AAS) pre-impregnation method and thermal modification were combined to improve the water-related properties of southern yellow pine (Pinus spp.) sapwood. Four types of AAS with varied alkyl chain lengths, including butyltrimethoxysilane (BTMOS), octyltrimethoxysilane (OTMOS), dodecyltrimethoxysilane (DTMOS), and cetyltrimethoxysilane (CTMOS), were used to pre-impregnate wood samples at a concentration of 5% or 15% mass fraction, and the subsequent thermal modification was processed at either 180 °C or 200 °C. The water absorption, dimensional stability, equilibrium moisture content (EMC), mechanical properties (modulus of rupture (MOR), and modulus of elasticity (MOE)), and mold resistance of the treated wood were evaluated. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to reveal the mechanism of the combined treatments in improving the properties of wood. Compared with thermal modification alone, the AAS combined treatment improved the water repellency, mechanical properties, and mold resistance of the modified wood. The study also identified the penetration of AAS into the wood cell wall and its reaction with the chemical components of the cell wall.
  • Researchpp 5299-5311Liu, X., Wu, Y., Shmulsky, R., Luo, Y., Wang, X., Chu, I., and Wan, H. (2016). "Developing a renewable hybrid resin system. Part I: Characterization of co-polymers of isocyanate with different molecular weights of phenolic resins," BioRes. 11(2), 5299-5311.AbstractPDF
    Co-polymer systems of methylene diphenyl diisocyanate (MDI) and phenol-formaldehyde (PF) resins with different molecular weights were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The FTIR and TGA coupled with differential thermogravimetric (DTG) results showed that higher molecular weight of PF resins not only promoted the reaction of isocyanate and PF co-polymer system, but also resulted in a better thermal property of prepared co-polymers. The XRD results revealed that higher molecular weight led to a higher proportion of ordered or crosslinking structures in the hybrid resin system. The relationship between the thermal resistance, mechanical properties and the molecular weights of phenolic resins needs further study.
  • Researchpp 5312-5321Hermoso, E., Mateo, R., Íñiguez-González, G., Montón, J., and Arriaga, F. (2016). "Visual grading and structural properties assessment of large cross-section Pinus radiata D. Don timber," BioRes. 11(2), 5312-5321.AbstractPDF
    The use of large cross-section timber for structural purposes has increased in Spain, and knowledge of its properties is strategically necessary. The Spanish visual strength-grading standard UNE 56544 (2011) efficiency applied to large cross-section structural timber was analyzed using a sample of 363 specimens of radiata pine (Pinus radiata D. Don.) from the Basque Country and Catalonia, Spain. Different sizes were tested (80 × 120 × 2400 mm3, 150 × 250 × 5600 mm3, 150 × 250 × 4300 mm3, and 200 × 250 × 5000 mm3). Bending strength, modulus of elasticity, and density were obtained, and characteristic values were determined in order to assign strength class according to European standard EN 338 (2010). Knots and twists were the most relevant singularities for visual strength grading. It was concluded that large cross-section Spanish radiata pine timber was suitable for structures, and it was assigned to the C20 strength class.
  • Researchpp 5322-5332Vila, C., Santos, V., Saake, B., and Parajó, J. C. (2016). "Manufacture, characterization, and properties of poly-(lactic acid) and its blends with esterified pine lignin," BioRes. 11(2), 5322-5332.AbstractPDF
    Pinus pinaster wood was pulped in ethanol/water medium catalyzed with sulfuric acid, and lignin was recovered from the liquid phase by precipitation upon water addition. Lignin samples were characterized for composition and thermal properties. Lignin samples were reacted with selected esterification agents (butyric, isobutyric, or crotonic anhydrides) under experimental conditions leading to extensive conversion of the available hydroxyl groups, and the esterified lignins were assessed for composition and thermal properties. Samples made up of crude polylactic acid or its blends with lignins (raw or esterified) were assayed for mechanical properties. The blends of polylactic acid with lignin modified with butyric anhydride presented higher Young’s modulus and elongation at break than neat polylactic acid.
  • Researchpp 5333-5342Rahmaninia, M., Javid, E., and Varshoei, A. (2016). "Process variables and the performance of cationic rosin as an internal sizing agent in recycled corrugated container pulp," BioRes. 11(2), 5333-5342.AbstractPDF
    Cationic rosin has many uses in papermaking; however, its performance as an internal sizing agent differs depending on the circumstance, especially in the recycling of pulps. In this study, a comprehensive laboratory approach was used to investigate the process variables affecting the cationic rosin application in the paper recycling process. In this respect, four levels of alum (0.5, 1.0, 1.5, and 2.0%) and four levels of cationic rosin (0.5, 1.0, 1.5, and 2.0%) were considered to find the best alum/cationic rosin combination in acidic conditions (pH 5). After considering all aspects of the paper, such as the mechanical properties (tensile, burst, and tear indices), wet resistance (Cobb test and dynamic contact angle test), and chemical usage (economically and environmentally-friendly procedures), the 1.0% alum and 0.5% cationic rosin levels were selected for optimum performance. This research also showed that the combined effect of alum with cationic rosin was favorable. Moreover, the sequence of alum and cationic rosin addition, which is a challenge in paper mills, also should be considered. The results indicated that the addition of cationic rosin after alum obtained the best mechanical and wet resistance results. In addition, the results showed that both acidic and neutral pH were acceptable in this sizing process.
  • Researchpp 5343-5357Kitchens, S., Amburgey, T. L., Barnes, H. M., and Seale, R. D. (2016). "Mechanical and durability properties of steam-pressed scrim lumber," BioRes. 11(2), 5343-5357.AbstractPDF
    This study shows that the mechanical properties of steam-pressed scrim lumber (SPSL) are sufficient for use in many commercial wood products and pass APA certification values. Values are greater than many of the commercial products on the market today. This study indicates that adding borates and/or silane-based water repellents before pressing combined with a silane-based water repellent after pressing is effective for producing durable SPSL material.
  • Researchpp 5358-5380Syed, N. N. F., Zakaria, M. H., and Bujang, J. S. (2016). "Fiber characteristics and papermaking of seagrass using hand-beaten and blended pulp," BioRes. 11(2), 5358-5380.AbstractPDF
    Marine angiosperms could inevitably offer considerable potential resources for their fiber, yet little research has been conducted, especially in Malaysia. Fiber characteristics of five species of seagrass – Enhalus acoroides, Cymodocea serrulata, Thalassia hemprichii, Halophila ovalis, and Halophila spinulosa – were evaluated. Fiber dimensions were studied to determine slenderness ratio, flexibility coefficient, Runkel’s ratio, and Luce’s shape factor species selection. The seagrass species have the potential in papermaking production as they possessed slenderness ratio >33 (98.12 to 154.08) and high Luce’s shape factor (0.77 to 0.83); however the species exhibited low flexibility coefficient <50 (30.07 to 35.18) and >1 Runkel’s ratio (1.11 to 1.60), which indicate rigid fiber. The five seagrass species have high cellulose >34% (40.30 to 77.18%) and low lignin content <15% (5.02 to 11.20%), which are similar to those encountered in non-wood plant species. Handmade paper sheet of Enhalus acoroides using pulp subjected to mechanical blending exhibited the highest tensile strength (4.16 kN/m) compared to hand-beaten pulp (3.46 kN/m). The highest breaking length (3.43 km) was achieved by a paper sheet of Thalassia hemprichii using hand-beaten pulp. Based on their physical and chemical composition properties, seagrass have potential as sources of fibrous material for handmade papermaking.
  • Researchpp 5381-5388Gangwar, A. K., Prakash, N. T., and Prakash, R. (2016). "An eco-friendly approach: Incorporating a xylanase stage at various places in ECF and chlorine-based bleaching of eucalyptus pulp," BioRes. 11(2), 5381-5388.AbstractPDF
    A potentially more environmentally compatible approach was evaluated, involving the use of an enzyme (X) stage optimally inserted into various bleaching sequences for Eucalyptus kraft pulps. The efficacy of the X stage was evaluated in terms of final brightness, CIE whiteness, post-color number (brightness reversion), effluent characteristics, etc. The results showed considerable benefits with an enzymatic pre-treatment bleaching sequence for improved final pulp brightness (1.6 units higher) and reduced adsorbable organic halogens (AOX) (32% lower), in addition to improved biological oxygen demand (BOD) to chemical oxygen demand (COD) ratio, when using 0.5 kg/t pulp dosage of xylanase; enzymatic post-treatment bleaching sequences were observed to boost final CIE whiteness up to 3.4 units and to reduce post color number by 48% at 0.5 kg/t pulp dosage of xylanase. In addition, approximately 32% reductions in AOX released, as well as appreciable improvement in BOD-to-COD ratio, were observed in the bleach effluents. An improved ratio of BOD-to-COD facilitates possible enhancement in the bio-degradability of discharge effluents in a secondary treatment stage. Nine different bleaching sequences were compared. Three sequences for each category (pre-treatment, intermediate, and post-treatment bleaching sequences) were performed to provide an overview of the influence of xylanase treatment on various pulp properties and environmental sum parameters of the ensuing effluents.
  • Researchpp 5389-5403Tu, Y., Huang, J., Xu, P., Wu, X., Yang, L., and Peng, Z. (2016). "Subcritical water hydrolysis treatment of waste biomass for nutrient extraction," BioRes. 11(2), 5389-5403.AbstractPDF
    Nutrients were extracted from corn stalks, peanut shells, de-oiled peanut meal, chicken manure, and sewage sludge by a subcritical water (SCW) hydrolysis reaction. Compared with the other feedstock, the aqueous phases extracted from de-oiled peanut meal showed the highest water-soluble organic carbon, amino acid, total nitrogen, and phosphorus contents. The effects of solution pH, final hydrothermal temperature, and reaction time on nutrient extraction from de-oiled peanut meal were investigated. The analysis showed that alkaline reagents promoted liquefaction. The highest yield of the total primary nutrients (82.6%) was obtained with extraction reaction at 180 °C for 1.5 h using 0.1 mol/L KOH. The liquid fraction from this reaction was investigated for its potential use as a fertilizer with germination experiments. A higher germination index and root activity were obtained using the liquid extract with the appropriate dilution. These results indicated that subcritical water hydrothermal treatment is a viable way to recover nutrients from biomass wastes. In addition, de-oiled peanut meal is a suitable feedstock for the production of nutrient-rich liquid extract.
  • Researchpp 5404-5423Kazeem, M. O., Shah, U. K. M., Baharuddin, A. S., and Rahman, N. A. (2016). "Enhanced cellulase production by a novel thermophilic Bacillus licheniformis 2D55: Characterization and application in lignocellulosic saccharification," BioRes. 11(2), 5404-5423.AbstractPDF
    Effects of nutritional and physicochemical factors were investigated for cellulase production by the newly isolated thermophilic strain Bacillus licheniformis 2D55 (Accession No. KT799651). The optimum cellulase production in shake flask fermentation was attained at 60 °C, pH 3.5, 180 rpm, and in a medium containing untreated sugarcane bagasse and pre-treated rice husk at 7% (w/v), urea, 1 g/L, peptone, 11.0 g/L, Mg(SO4)2, 0.40 g/L, CaCl2, 0.03 g/L, Tween 80, 0.2% (w/v), and 3% inoculum. The highest caboxymethyl cellulase (CMCase), filtre paperase (FPase), and β-glucosidase produced under the optimized conditions were 29.4 U/mL, 12.9 U/mL, and 0.06 U/mL, respectively, after 18 h of fermentation. Optimization of the parameters increased the CMCase, FPase, and β-glucosidase activities by 77.4-fold, 44.5-fold, and 10-fold, respectively. The crude enzyme was highly active and stable over broad temperature (50 to 80 °C) and pH (3.5 to 10.0) ranges with optimum temperature at 65 °C and 80 ºC for CMCase and FPase, respectively. The optimum pH for CMCase and FPase was 7.5 and 6.0, respectively. Saccharification of sugar cane bagasse and rice husk by crude cellulase resulted in perspective yields of 0.348 and 0.301 g g-1 dry substrate of reducing sugars. These results suggest prospects of thermostable cellulase from B. licheniformis 2D55 in application for bio-sugar production and other industrial bioprocess applications involving high temperatures.
  • Researchpp 5424-5434Klement, I., and Huráková, T. (2016). "Determining the influence of sample thickness on the high-temperature drying of beech wood (Fagus sylvatica L.)," BioRes. 11(2), 5424-5434.AbstractPDF
    Drying time reduction has always been a major concern in the drying process and is achievable by increasing the temperature of the surrounding air. To optimize the quality of the resulting material, drying conditions must be enhanced to reach a balanced correlation between the drying time and quality of the dried timber. This paper analyses the high-temperature drying of wood and the optimization of this process, as well as the effect that drying temperature and thickness of beech timber specimens has on the drying process. The high-temperature drying of beech wood was carried out by means of hot air in a laboratory drier for maximum 33 hours at maximum temperatures of 130 and 150 °C. The initial moisture content of samples was approximately 70%. The resulting drying times were short in comparison to conventional warm-air drying, which is caused by the high intensity of drying during the removal of bound water. Finally, it can be concluded that the thickness of the dried specimens is a significant factor in the process of high-temperature drying of beech wood.
  • Researchpp 5435-5451Ren, H., Chen, C., Wang, Q., Zhao, D., and Guo, S. (2016). "The properties of choline chloride-based deep eutectic solvents and their performance in the dissolution of cellulose," BioRes. 11(2), 5435-5451.AbstractPDF
    A series of choline chloride-based deep eutectic solvents (ChCl-DESs) were synthesized and characterized, and their performance in the dissolution of cellulose was investigated. The hydrogen-bond donors significantly (β-value) affected the properties of ChCl-DESs, causing differentiated dissolution performances. ChCl- imidazole (Im) showed the highest Hammett acidity function (1.869), hydrogen bond basicity (0.864), and dipolarity/polarizability effect (0.382) among the ChCl-DESs. The ChCl-Im showed the lowest pseudo-activation energy for viscous flow (31.76 kJ mol-1) among the ChCl-DESs. The properties of ChCl-Im caused the highest solubility of cellulose (2.48 wt.%) relative to the other ChCl-DESs. Polyethylene glycol (PEG), as a co-solvent, significantly (β-value) enhanced the accessibility of ChCl-Im to cellulose by breaking the supramolecular structure of cellulose, promoting its dissolution. The decrystallization of ChCl-Im-coupled PEG approximately doubled the dissolving capabilities, and the solubility increased by more than 80% in comparison with only ChCl-Im. The cellulose was directly dissolved by ChCl-Im-coupled PEG, and no other derivatives were produced.
  • Reviewpp 5452-5481Espinoza-Acosta, J. L., Torres-Chávez, P. I., Ramírez-Wong, B., López-Saiz, C. M., and Montaño-Leyva, B. "Antioxidant, antimicrobial, and antimutagenic properties of technical lignins and their applications," BioRes. 11(2), 5452-5481.AbstractPDF
    At present, more than 70 million tons per year of technical lignins are obtained from cellulose pulping and lignocellulosic refineries (e.g., kraft, lignosulfonates, soda, and organosolv lignin). These lignins are commonly incinerated to produce steam and energy, and only a small part is used as an additive in various low volume and niche applications, such as dispersant, in concrete admixtures, as an adhesive and as a binder. Furthermore, the potential of technical lignins is considered to be beyond that of an inexpensive fuel or raw material to produce low added value products. The technical lignins consist of complex polyphenolic polymers that contain numerous chemical functional groups, such as phenolic hydroxyl, carboxylic, carbonyl, and methoxyl groups. The phenolic hydroxyl and methoxyl groups present in lignin reportedly possess various biological activities. The amount of data describing the biological activities of technical lignins has increased in the last 10 years. This review presents the most relevant research concerning the various biological activities (antioxidant, antimicrobial, antimutagenic, and others) of technical lignins. Additionally, the most promising and relevant applications are highlighted.
  • Reviewpp 5482-5499Matsakas, L., Rova, U., and Christakopoulos, P. " Strategies for enhanced biogas generation through anaerobic digestion of forest material - An overview," BioRes.11(2), 5482-5499.AbstractPDF
    Incorporation of biofuels into the existing selection of fuels is a very important measure to slow down environmental destruction and to counter the imminent fossil fuel shortage. Biogas is a very interesting option for use in both electricity and heat production, and also as a fuel for vehicles. The positive fuel characteristics of biogas and the high yields of biogas obtained from traditional raw materials (e.g., animal manure) have resulted in operation of several commercial units around the globe. On the other hand, there is an increased demand for biogas production which, for the need to be met, should have renewable resources incorporated into it. Forest materials are an interesting candidate, and there is a rising interest in the research and industrial communities to exploit them as raw materials for anaerobic digestion in biogas production. In this review article, we aim to give the reader an insight into the most recent processes for conversion of various sources of forest materials into biogas.
  • Reviewpp 5500-5552Hubbe, M. A., and Koukoulas, A. A. (2016). "Wet-laid nonwovens manufacture - Chemical approaches using synthetic and cellulosic fibers," BioRes. 11(2), 5500-5552.AbstractPDF
    Wet-laid forming, which can be regarded as being analogous to conventional papermaking processes but with use of chopped synthetic or staple fibers, continues to draw attention as an advantageous way to prepare advanced nonwoven textile products. This review of the literature considers scientific advances in the field, with emphasis placed on applications involving cellulosic fibers as a significant component of the product. Some primary challenges with respect to wet-laid processing concern the dispersion of the synthetic fibers in aqueous media and methods for avoiding their subsequent entanglement. Both mechanical and chemical strategies have been employed in order to achieve well-formed sheets of high uniformity and binding among the fibers to meet a variety of end-use specifications. The incorporation of cellulosic fibers has been shown to facilitate fiber dispersion and to impart certain beneficial characteristics and properties to wet-laid fabrics. The contrasting attributes of synthetic and cellulosic fibers contribute to some unique challenges during the processing of their mixtures during wet-laid forming.
  • Reviewpp 5553-5564Chen, C., Duan, C., Li, J., Liu, Y., Ma, X., Zheng, L., Stavik, J., and Ni, Y. (2016). "Cellulose (dissolving pulp) manufacturing processes and properties: A mini-review," BioRes.11(2), 5553-5564.AbstractPDF
    The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to a significant development of dissolving pulps in the last decade. In this review paper, the current status of dissolving pulp with respects to raw materials, manufacturing processes, and some key issues are discussed. Non-wood materials and the process concept of upgrading paper-grade pulp into dissolving pulp are also included. Some recent developments related to the analytical methods of the purity and molecular weight distribution based on the ion chromatography and gel permeation chromatography are discussed. Finally, further processing improvements of purification, such as mechanical, chemical, and enzymatic treatment, and their combinations during the manufacturing process of dissolving pulp, are included.
  • Reviewpp 5565-5580Rosli, F., Ghazali, C. M. R., Abdullah, M. M. A. B., and Hussin, K. (2016). "A review: Characteristics of oil palm trunk (OPT) and quality improvement of palm trunk plywood by resin impregnation," BioRes . 11(2), 5565-5580.AbstractPDF
    Due to the shortage of solid wood as a raw material of plywood and the abundance of oil palm trunk (OPT) waste in Malaysia, OPT has become one of the potential replacements for timber. However, OPT plywood has low performance compared with commercial plywood, due to the poor properties of OPT. There are many recent studies related to quality improvement using thermosetting impregnation, especially with formaldehyde-based resins such as urea formaldehyde (UF) and phenol formaldehyde (PF). Nevertheless, there are very limited studies related to palm trunk plywood using thermoplastic impregnation and formaldehyde-free adhesive. Formaldehyde effects can be avoided by replacing it with a thermoplastic adhesive, such as acrylonitrile butadiene styrene (ABS), to enhance and improve the quality of the plywood manufactured from OPT. In Malaysia, palm trunk plywood is used currently for non-structural materials such as formworks, cabinets, and packaging material. Hence, the enhanced quality of palm trunk plywood with a formaldehyde-free thermoplastic adhesive could produce a higher quality palm trunk plywood.
  • Reviewpp 5581-5599Mou, H. L., Wu, S., and Fardim, P. (2016). "Applications of ToF-SIMS in surface chemistry analysis of lignocellulosic biomass: A review," BioRes. 11(2), 5581-5599.AbstractPDF
    Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) is an advanced surface-sensitive technique that can provide both spectral and imaging information about materials. Recently, ToF-SIMS has been used for advanced studies of lignocellulosic biomass. In the current article, the application of ToF-SIMS to the characterization of the surface chemical composition and distribution of biomass components in lignocelluloses is reviewed. Moreover, extended applications of ToF-SIMS in the study of pretreatments, modification of biomaterials, and enzyme activity of lignocellulosic materials are presented and discussed. Sample preparation prior to ToF-SIMS analysis and subsequent interpretation of results is a critical factor in ensuring reliable results. The focus of this review is to give a comprehensive understanding of and offer new hints about the effects of processing conditions on the surface chemistry of lignocellulosic biomass.
  • Reviewpp 5600-5617Tajuddin, M., Ahmad, Z., and Ismail, H. (2016). "A review of natural fibers and processing operations for the production of binderless boards," BioRes. 11(2), 5600-5617.AbstractPDF

    Decreasing wood supplies and the need for formaldehyde-free particleboard have become important issues. This has led to studies about the use of raw materials other than wood, along with the manufacture of particleboard without using any synthetic adhesives. This paper presents an overview of the development of binderless boards from natural fibers using a diverse range of manufacturing processes, such as heat and steam treatments. The features of binderless boards produced with various parameters, such as pressing parameters, particle sizes, and additional substances, under various manufacturing processes, are discussed. Based on the availability of natural fibers, binderless boards are typically evaluated for their physical, mechanical, and thermal properties. This review is approached with an understanding of the processes and contributing factors in producing binderless boards, helping to overcome some critical issues that are necessary for the development of future new “green” binderless boards through value-addition to enhance their usage.

  • Reviewpp 5618-5640Villaverde, J. J., Sandín-España, P., Sevilla-Morán, B., López-Goti, C., and Alonso-Prados, J. L. (2016). "Biopesticides from natural products: Current development, legislative framework, and future trends," BioRes . 11(2), 5618-5640.AbstractPDF
    The importance of biomass as a source of chemicals, biofuels, and energy is widely accepted. Currently, the attention is mainly focused on the valorisation of by-products from lignocellulosic materials. Chemical compounds derived from plants and microorganisms that provide good protection for crops against weeds, pests, and diseases (biopesticide active substances) have been used to formulate pesticides. Their use is increasingly encouraged by new pesticide regulations that discourage the use of harmful active substances. This article reviews the current and future situation of biopesticides, especially natural chemical products, and focuses on their potential within the European pesticide legislative framework. Moreover, this article highlights the importance of the different modes/mechanisms of action of the active substances obtained from natural sources, the role of chemistry in biopesticide development, and how the adoption of integrated pest management practices contributes to a greater trend towards biopesticides.
  • Reviewpp 5641-5655Arévalo Gallegos, A. M., Carrera, S. H., Parra, R., Keshavarz, T., and Iqbal, H. M. N. (2016). "Bacterial cellulose: A sustainable source to develop value-added products - A review," BioRes. 11(2), 5641-5655.AbstractArticlePDF

    In recent decades, worldwide economic and environmental issues have prompted research scientists to re-direct their interests to bio-based resources, which are sustainable in nature. In this context, microbial polysaccharides, such as bacterial cellulose (BC), also known as microbial cellulose (MC), are some of the upcoming and emergent resources and have potential application in various bio- and non-bio-based sectors of the modern world. Many researchers have already established novel BC/MC production methods, and many new studies have been published on lab-scale and large-scale production aspects of BC/MC to date. To further expand the novel use of this sustainable source, significant progress toward the development of BC/MC has appeared in recent years. Specifically, there have been many publications and/or research reports on the valorization of BC/MC in the food, paper, materials, biomedical, pharmaceutical, and cosmeceutical industries, among others. This review will address the novel application aspects of BC/MC today, with the aim of demonstrating the importance of this sustainable and novel source in the development of value-added products.