NC State
  • Editorialpp 2182-2183Laleicke, P. (2018). "Wood waste, the challenges of communication and innovation," BioRes. 13(2), 2182-2183.AbstractPDF

    Wood is our material of choice for sustainable and environmental friendly construction and manufacturing of products. Wood has excellent properties for reuse, realized and implemented through a cascading utilization, introducing intermittent product lives. In contrast, wood waste is still a heavily under-valued resource in North America. With current practices of sourcing virgin wood at lowest cost and few efforts to shift wood out of the single-use convenience mode of utilization, true innovation is unlikely to occur. Technical problems have been assessed and solved. What remains is collecting and combining unintelligently scattered and hidden information about wood utilization into a single place. And, if connecting a complimentary feedstock supply to our current industries remains a challenge, then innovation must happen on the product-side too.

  • Editorialpp 2184-2186Chen, Z., Zhang, L., and He, Z. (2018). "Rethinking the determination of wet strength of paper," BioRes. 13(2), 2184-2186.AbstractPDF

    The wet strength of paper is an important physical property, especially for household paper, e.g., paper towels, as well as for some functional paper grades. However, in the literature, various conditions of immersing the samples in water before testing have been reported, resulting in differences in their extent of saturation and inconsistency in the testing results. Also, the dryness of paper specimens before the wet-strength testing is a critical parameter for the wet strength of paper; however, this aspect has been neglected in the literature. In this editorial, the methods of examination for both the temporary and permanent wet strength are discussed. A more reasonable method is proposed, such that the wet strength is reported according to the immersion time and the initial dryness of the paper. As an option, the results may be expressed as a function of immersion time and initial dryness. In this way, the trend of temporary wet strength related to the immersion time in water can be expressed clearly and the permanent wet strength also can be evaluated comprehensively.

  • Researchpp 2187-2203Alves de Oliveira, R., Komesu, A., Vaz Rossell, C. E., Wolf Maciel, M. R., and Maciel Filho, R. (2018). "Evaluation of hybrid short path evaporation to concentrate lactic acid and sugars from fermentation," BioRes. 13(2), 2187-2203.AbstractPDF

    Lactic acid is an important organic compound that finds various applications in the chemical, pharmaceutical, food, and medical industries. Many of these applications require lactic acid with high purity. Hybrid short path evaporation (HSPE) is a separation process well studied in the petrochemical sector that is mainly used to obtain compounds with high purity. It is also a process offering small residence time, low pressure, and environmentally friendliness. The concentration process of lactic acid was studied by using HSPE in the presence of high total reducing sugar content remaining from sugarcane molasses fermentation. In this work, the influence of operational conditions, such as evaporator temperature (86.4 °C to 153.6 °C), internal condenser temperature (7.95 °C to 18 °C), and feed flow rate (8.27 to 21.7 mL/min), on lactic acid concentration and mass percentages were evaluated. The results showed that all variables influenced the process. Mathematical models were developed for the mass percentage and concentration of the total reducing sugar in the distilled stream and for the mass percentage at residue stream. Under the best operational conditions, the concentration of lactic acid (≈ 247.7 g/L) was 2.5 times higher than the initial fermentation broth (≈ 100.1 g/L).

  • Researchpp 2204-2217Feng, Y., Zhong, H., Liang, Y., Lei, B., Chen, H., Yin, X., and Yu, X. (2018). "Structure and compositional changes of eucalyptus fiber after various cycles of continuous screw extrusion steam explosion," BioRes. 13(2), 2204-2217.AbstractPDF

    A continuous screw extrusion steam explosion (SESE) pretreatment method was used to disrupt the structure of eucalyptus fiber. The effects of increasing numbers of SESE pretreatment cycles on the structure and composition of eucalyptus fiber were investigated. Lignin was isolated from the eucalyptus fiber via the phosphoric acid method under modest reaction conditions (50 °C), and was characterized. The SESE pretreatment led to a decrease in crystallinity and degraded the hemicellulose and cellulose. The surface of the eucalyptus fiber was damaged by SESE pretreatment, and significant surface debris were observed. The isolated lignin was typical of guaiacyl-syringyl (G-S)-enriched lignin of eucalyptus hardwood. The SESE pretreatment led to the cleavage of ether linkages and condensation of lignin, and thus a more heterogeneous structure compared with that of raw lignin. The increased molecular weight of SESE-pretreated lignin showed that condensation was more pronounced with increased numbers of SESE cycles. The thermostability of lignin increased after three SESE cycles and remained stable with further cycles. This corresponded to the trend in the molecular weight of lignin with increased SESE pretreatment. The SESE pretreatment was more efficient for pretreating eucalyptus fiber than conventional batch-type steam explosion, and thus is more suitable for industrial application.

  • Researchpp 2218-2232Lai, Z., Li, S., Zhang, Y., Li, Y., and Mu, J. (2018). "Influence of urea formaldehyde resin on the pyrolysis of biomass components: Cellulose, hemicellulose, and lignin," BioRes. 13(2), 2218-2232.AbstractPDF

    Wood-based panels, which are often used and then abandoned, are a potential resource for energy recovery. To better understand the pyrolysis of wood-based panels, the effect of urea formaldehyde (UF) resin on the pyrolysis of the wood components (cellulose, hemicellulose, and lignin) was investigated. Thermogravimetric analysis (TGA), gas chromatography coupled with mass spectrometry (GC-MS), and an ultimate analysis were used to investigate the pyrolysis process and products of the biomass components mixed with 10% UF resin. The UF resin specifically inhibited the decomposition rate of cellulose and promoted the thermal decomposition of lignin. For xylan, the UF resin had little impact. The UF resin mainly affected the mass loss of C and O. Loss of both elements in lignin was promoted, but only C loss increased in cellulose. The nitric gases generated from the pyrolysis mixtures were HCN and NH3, and N from the UF resin tended to transform into NH3. Influence of the UF resin on the pyrolysis liquids was mainly seen on the N compounds. With the addition of the UF resin, more nitrogenous compounds were detected in the pyrolysis liquids. The relative contents of nitrogenous compounds in the pyrolysis liquids from cellulose and lignin were 12.8% and 64.3%, respectively.

  • Researchpp 2233-2246Lan, H., Zhang, H., Yang, D., Bi, S., Liu, J., Wang, W., and Zhang, H. (2018). "Screening predominant bacteria and construction of efficient microflora for treatment of papermaking white water," BioRes. 13(2), 2233-2246.AbstractPDF

    Three strains of bacteria were isolated and purified from activated sludge for white water treatment in the laboratory. These strains were identified as Bacillus subtilis, Bacillus cereus, and Virgibacillus pantothenticus through a morphological analysis, the MIDI Sherlock automatic microbial identification system, and 16S rRNA methods. The results of the construction of efficient microflora for white water showed that a mass percentage ratio of B. subtilis, B. cereus, and V. pantothenticus of 50%:35%:15% achieved an optimal treatment effect. Analysis by gas chromatograph-mass spectrometer (GC-MS) established that the content of characteristic pollutants in white water decreased notably after treatment with the efficient microflora, and detected the intermediate products of short chain fatty acids, alcohols, and other compounds. Moreover, through measuring the removal rate of chemical oxygen demand (COD), electrical conductivity, and cationic demand (CD), the optimal retention time for white water treatment with the efficient microflora was 4 h to 6 h, and when the removal rate of COD reached approximately 90%, the electrical conductivity and the cationic demand were reduced to lower values.

  • Researchpp 2247-2267Tanase, C., Domokos, E., Coșarcă, S., Miklos, A., Imre, S., Domokos, J., and Dehelean, C. A. (2018). "Study of the ultrasound-assisted extraction of polyphenols from beech (Fagus sylvatica L.) bark," BioRes. 13(2), 2247-2267.AbstractPDF

    The aim of this study was to reach the best efficiency of total polyphenols extraction from beech bark. The impacts of solvent concentration, sonication time, and temperature were investigated relative to the yield of extractives from beech (Fagus sylvatica L.) bark using ultrasound-assisted extraction at 40 kHz ultrasonic frequency. All extracts were characterized quantitatively in terms of total content in polyphenols. The extracts obtained in the optimized conditions were also evaluated qualitatively. Beech bark can be a rich raw material for obtaining bioactive polyphenols. An experimental planning method was described that optimized the process and increased the extraction yield. In the experiments, water and ethanol:water solvent solutions were used. The efficiency of the extraction process was determined based on a factorial analysis of variance. The maximum extraction yield of total polyphenols (72.716 mg gallic acid equivalents/g beech bark) was obtained using a processing time of 20 min, an extraction temperature of 65 °C, and an ethanol solvent concentration of 70%. The extracts obtained under the optimum conditions were characterized to determine potential uses of beech bark extractives. The results obtained indicated that ultrasound-assisted extraction was an efficient method for the extraction of natural compounds from beech bark; thus, this method allows for the full utilization of this abundant and low-cost industrial waste.

  • Reviewpp to be addedSu, Y., Yang, B., Liu, J., Sun, B., Cao, C., Zou, X., Lutes, R., and He, Z. (2018). "Prospects for replacement of some plastics in packaging with lignocellulose materials: A brief review," BioRes. 13(2), Page numbers to be added.AbstractPDF

    There has been increasing concern regarding environmental problems arising from the widespread use of petroleum-based plastic materials for packaging. Many efforts have been made to develop sustainable and biodegradable packaging materials to replace plastic products. The current review summarizes recent research progress in developing cellulose packaging materials to replace plastics used for cushioning and barrier packaging functions based on pulp fibers, cellulose nanofibers, and regenerated cellulose films to benefit from their renewability, sustainability and biodegradability. The cushioning packaging materials include molded pulp products and bio-based foams. Advanced cellulose films and paper can be good barriers for oxygen and carbon dioxide gases, as well as for water vapor. Several cellulose fiber-based packaging products have been commercialized in areas that used to be occupied solely by plastic products.

  • Researchpp 2268-2282Cruz, N., Bustos, C., Aguayo, M. G., Cloutier, A., and Castillo, R. (2018). "Impact of the chemical composition of Pinus radiata wood on its physical and mechanical properties following thermo-hygromechanical densification," BioRes. 13(2), 2268-2282.AbstractPDF

    The thermo-hygromechanical densification process changes the chemical composition and the physical and mechanical properties of wood. The aim of this work was to study the impact of the chemical composition of Pinus radiata wood on its physical and mechanical properties following the thermo-hygromechanical densification process. The samples were initially segregated by lignin content. Density, hardness, modulus of elasticity (MOE), and modulus of rupture (MOR), in addition to lignin, α-cellulose, hemicellulose, and extractive contents, were determined before and after the densification process. The results indicated that densified wood with high initial lignin content had greater rate of increases in density and MOE than wood with lower initial lignin content. Additionally, densified wood with lower initial lignin content had greater rate of increases in hardness. The rate of increase of MOR did not show significant differences within both groups. Carbohydrates present in the control and the densified wood played an important role in the mechanical strength of the final product.

  • Researchpp 2283-2292Jiang, W., Tomppo, L., Pakarinen, T., Sirviö, J., Liimatainen, H., and Haapala, A. (2018). "Effect of cellulose nanofibrils on the bond strength of polyvinyl acetate and starch adhesives for wood," BioRes. 13(2), 2283-2292.AbstractPDF

    Nanocellulose is a competitive reinforcement material for use in biocomposite structures and fibrous products. In this study, adhesive mixtures of dicarboxylic acid cellulose nanofibrils (CNF) were dispersed into commercial polyvinyl acetate (PVAc) and starch adhesives, which were applied to Norway spruce (Picea abies) to assess their performance in wood joining. Single-lap joints were prepared and tested with PVAc mixtures with 0 to 0.64 wt% CNF and starch glue mixtures containing 0 to 1.07 wt% CNF. CNF suspensions having three concentrations (0.64, 0.96, and 1.28%) were compared. The results showed that the optimum amount of CNF, 0.48% suspensions, added to PVAc increased the average lap joint strength (EN 205:2003) by 74.5% when compared to control specimens with pure PVAc. Correspondingly, 0.96% CNF suspensions also enhanced the strength of starch adhesive by 34.5%. Lower and higher CNF concentrations showed clearly inferior performance.

  • Researchpp 2293-2303Liu, X., Zu, X., Liu, Y., Sun, L., Yi, G., Lin, W., and Wu, J. (2018). "Conversion of waste water hyacinth into high-value chemicals by iron (III) chloride under mild conditions," BioRes. 13(2), 2293-2303.AbstractPDF

    This study examined a novel approach for converting waste water hyacinths into high-value chemicals under low temperature and low atmospheric pressure by using iron (III) chloride (FeCl3), an oxidant that has the unique properties of nontoxicity, low-cost, and abundance. The conversion process and transformation products of water hyacinths under different conditions were investigated and characterized. The results showed that the content of lignocellulose gradually decreased in the reaction solution. The chemical structure of lignocellulose in the water hyacinths was changed, and the glycosidic bonds of the water hyacinths were cleaved. The surface structure and crystalline regions of the water hyacinths were also damaged during the reaction. Furthermore, the hemicellulose and cellulose in the water hyacinths were dissolved and hydrolyzed to reducing sugars in the reaction solution, and then the reducing sugars were further dehydrated to hydroxymethylfurfural (HMF) and furfural. Lignin in the water hyacinths was depolymerized into aromatic and hydrocarbon compounds. The process presented in this study effectively alleviates environmental pollution by efficient utilization of aquatic wastes, and it produces high-value chemicals from biomass waste.

  • Researchpp 2304-2327Sakdaronnarong, C., Srimarut, N., Chantasod, R., Sraphet, S., Triwitayakorn, K., and Jonglertjunya, W. (2018). "Enzyme matching design approach on very high gravity liquefaction and saccharification of cassava root and cassava starch for ethanol fermentation," BioRes. 13(2), 2304-2327.AbstractPDF

    During ethanol production, the ratio of various sources of starch-hydrolyzing enzymes significantly influences hydrolysis efficiency in a very high gravity (VHG) system. In this study, the enzyme matching approach was proposed to optimize liquefaction and saccharification yield of cassava root and cassava starch. For fresh cassava root, the synergistic effect of using Techzyme Q-Add enzyme (93 °C pH 5.6) for liquefaction and GC 147 enzyme (61.5 °C pH 4.2) for saccharification achieved the highest yield among all enzyme-matching designs. At 25% solid, highest total reducing sugar (TRS) yields from sequential liquefaction and saccharification of cassava starch, fresh cassava, and dry cassava were 87.9%, 85.1%, and 70.0% corresponding to 286.8, 249.4, and 241.1 g/L, respectively. For VHG ethanol fermentation by Saccharomyces cerevisiae TISTR 5606, separate liquefaction and simultaneous saccharification and fermentation (SLSSF) gave a significantly higher ethanol concentration compared with separate liquefaction and saccharification and fermentation (SLSF). From a 35% solid SLSSF system, the highest ethanol produced at 30 °C was 27.3 g/L from 72 h, respectively. The results suggested that SLSSF could effectively shorten the time course of the whole process for liquefaction, saccharification, and fermentation from 74 h to only 26 h for similar ethanol production yields.

  • Researchpp 2328-2341Gou, G., Wang, Q., Xie, W., Cao, J., Jiang, M., He, J., and Zhou, Z. (2018). "Assessment of instant catapult steam explosion treatment on rice straw for isolation of high quality cellulose," BioRes. 13(2), 2328-2341.AbstractPDF

    Instant catapult steam explosion (ICSE) was applied to treat rice straw for isolating high quality cellulose. After ICSE treatment under the condition of maintaining the pressure at 2.0 MPa for 11 min, the hemicellulose content decreased to 3.70% from the original 20.10%, and the content of α-cellulose was 72.02%. The enormous explosion power density provided by ICSE turned rice straw into cellulosic fibers with good accessibility, as well as it protected the cellulose fibers from being over-hydrolyzed. All of the straw cellulosic samples were analyzed by scanning electron microscopy (SEM), Fourier transformation infrared spectrometry (FTIR), and X-ray diffraction (XRD) to collectively examine the impact of ICSE treatment on the structure and morphology of the cellulose components. The recycled lignin was also analyzed by two-dimensional nuclear magnification resonance spectrometry (2D NMR) to understand the mechanisms underlying the ICSE treatment.

  • Researchpp 2342-2355Knapic, S., Grahn, T., Lundqvist, S. O., and Pereira, H. (2018). "Juvenile wood characterization of Eucalyptus botryoides and E. maculata by using SilviScan," BioRes. 13(2), 2342-2355.AbstractPDF

    The wood properties of 6-year-old Eucalyptus botryoides and Eucalyptus maculata point towards a possible aptitude for solid-wood end uses. Samples from E. botryoides and E. maculata were characterized regarding within-tree variation in wood density, radial and tangential fibre width, fibre wall thickness, fibre coarseness, microfibril angle, and stiffness based on SilviScan measurements taken radially from the pith outwards at varying stem height levels. The mean values of the studied wood properties for E. botryoides and E. maculata were, respectively: density 507 kg m-3 and 695 kg m-3, radial fibre width 17.4 µm and 17.2 µm, tangential fibre width 16.7 µm and 16.9 µm, fibre wall thickness 1.8 µm and 2.5 µm, fibre coarseness 161.2 µgm-1 and 212.9 µgm-1, microfibril angle 15.5° and 14.7°, and stiffness 9.6 GPa and 12.1 GPa. The variation in wood stiffness was explained to a large extent by microfibril angle and wood density variations. The results of the scans, along with the wood variability, indicated that both species should be considered for solid wood products or pulp production.

  • Researchpp 2356-2373Xu, J., Li, M., and Sun, R. (2018). "Successive fractionations of hemicelluloses and lignin from sorghum stem by sodium hydroxide aqueous solutions with increased concentrations," BioRes. 13(2), 2356-2373.AbstractPDF

    Sorghum stem, an agricultural solid waste discarded in large amounts, was effectively fractionated into its chemical components to achieve value-added utilization. The stem was successively extracted using water at 80 °C and alkali aqueous solutions with increased concentrations (1% NaOH; 60% ethanol containing 1% NaOH, 3% NaOH, 5% NaOH, and 8% NaOH) at 50 °C, which yielded hemicellulose and lignin fractions as well as a cellulose-rich residue. The hemicellulose and lignin fractions were characterized in terms of yield, sugar components, alkaline nitrobenzene, and oxidation analysis. In addition, the molecular weights were determined by gel permeation chromatography and the structures were further identified by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The results indicated that the hemicelluloses yielded from the alkali aqueous solution had a linear xylan structure. The alkali lignin had a typical guaiacyl/syringyl/p-hydroxypheny structure and low amounts of contaminating sugars (less than 2%). A high concentration of alkali aqueous solution led to the release of lignin with a large molecular weight, whereas increasing the alkali concentration resulted in lignin degradation. The residual stem after the successive extractions was rich in cellulose and had a low crystallinity. In sum, mild successive extractions are a promising way to fractionate sorghum stem waste for further conversion.

  • Researchpp 2374-2396Salanti, A., Zoia, L., Simonutti, R., and Orlandi, M. (2018). "Epoxidized lignin derivatives as bio-based cross-linkers used in the preparation of epoxy resins," BioRes. 13(2), 2374-2396.AbstractPDF

    Lignin, which is the most abundant aromatic polymer in nature, was used as a green substitute for the toxic bisphenol A. In particular, the ability of epoxidized lignin to simultaneously serve as a cross-linker and rigid segment was investigated. The epoxidized lignin was preferably reacted with a monofunctional amine, which acted as a chain extender, to evaluate its performance as a cross-linker, and in the presence of poly(ethylene glycol) diglycidyl ether as a soft segment to adjust the resin properties. Different poly(ethylene glycol) diglycidyl ether/lignin stoichiometric ratios were tested, whereas the amine/epoxy equivalent ratio was fixed at 1:2. Some of the remarkable resin samples were subjected to differential scanning calorimetry analysis and compared with blank samples that did not include lignin in the composition. Moreover, the evolution over time of the molecular weight distribution of the selected compositions was analyzed by gel permeation chromatography until the solubility in tetrahydrofuran was appreciable.

  • Researchpp 2397-2410Zhang, L., Jia, Y., He, H., Yin, J., Chen, R., Zhang, C., Shen, W., and Wang, X. (2018). "Multiple factor analysis on preparation of cellulose Nanofiber by ball milling from softwood pulp," BioRes. 13(2), 2397-2410.AbstractPDF

    This work aimed to investigate the effects of various single factors and their interactions on the preparation of cellulose nanofiber (CNF) using ball milling. These factors included the milling ball size, milling time, mass ratio of milling ball to cellulose pulp, and alkali concentration, as well as their complicated interactions. The Taguchi method was applied to the experimental design to systematically study the influences of these factors on the yield of CNF. A method for evaluating the yield of CNF was developed. Both of the simple analysis (SA) and analysis of variance (ANOVA) of the experimental results indicated that the most significant factor influencing the yield of CNF was the mass ratio of milling ball to cellulose pulp. The interactions between this factor and other single factors, e.g., milling time, also showed significant influence on the yield of CNF. Although the influence of milling ball size was negligible, its interaction with mass ratio of milling ball to cellulose pulp must be considered during production. Based on these findings, a mini scaled-up practice was proposed to demonstrate the possibility of the application of ball milling on the mass production of CNF.

  • Researchpp 2411-2423Song, X., Shangguan, W., Zhang, L., Yuan, Y., and Lei, Y. (2018). "Effect of different boiling treatments on physical properties of cork from Quercus variabilis," BioRes. 13(2), 2411-2423.AbstractPDF

    Effects of different boiling treatments were evaluated relative to various physical properties of cork from Quercus variabilis before and after treatment, including volume, density, hardness, compression resilience ratio, and color. The boiling water treatment decreased the density, hardness, and lightness of cork. Water absorption amount of cork boiled at 100 °C for 30 min to180 min increased from 28.85% to 52.50%, and expansion in the radial direction was 15.4% to 19.5%. The total color difference (ΔE*) of cork gradually increased with increased boiling time. The values of the compression resilience ratio of all corks after a pressure release at 24 h were >80%. Cork samples boiled at 100 °C for 60 min, and then dried under different temperatures (140 °C to 240 °C), had volume expansion between 35.6% and 65.3%. With increased drying temperature, the ΔE* of cork increased. Cork boiled at 100 °C for 60 min followed by microwave irradiation of different times (2 min to 8 min) had volume expansion of 39.7% to 54.5%. Microwave treatment had little influence on cork color. The sodium hydroxide solution boiling treatment decreased cork lightness, while the hydrogen peroxide-treated cork lightness increased with the increasing of solution concentration, and ΔE* slightly increased.

  • Researchpp 2424-2439Záborský, V., Borůvka, V., Kašičková, V., and Gaff, M. (2018). "The effect of selected factors on Domino joint stiffness," BioRes. 13(2), 2424-2439.AbstractPDF

    When designing wooden structures and furniture, it is very important to consider joints that allow the structure to stay together and upright. There are many different types of wood joints. The selection of a joint type and its properties are some of the most important design choices. This article was dedicated to the Domino joint, which allows for strong joints. The Domino joiner is a loose tenon and mortise manufacturing joining tool. This article discusses the effect of selected parameters, such as the type of stress (tensile and compressive), size of the Domino joiner (one-half and one-third thickness), wood species (beech (Fagus sylvatica L.) and spruce (Picea abies L.)), and adhesive type (polyvinyl acetate and polyurethane), on the joint stiffness. The influence of the annual rings was also monitored.

  • Researchpp 2440-2451Park, S. Y., Kim, J. C., Yeon, S., Yang, S. Y., Yeo, H., and Choi, I. G. (2018). "Rapid prediction of the chemical information of wood powder from softwood species using near-infrared spectroscopy," BioRes. 13(2), 2440-2451.AbstractPDF

    Five different softwoods were used to investigate fast methods for predicting quantitative chemical information via near-infrared (NIR) spectroscopy. In biomass-related industries, fast collection of chemical information from a feedstock is needed. Prior to predicting quantitative information, a principal component analysis (PCA) using NIR spectra was conducted to evaluate the possibility of discriminating the softwoods. As a result of PCA, the five species were divided into three groups. This result indicated that the extractive compounds were key factors because the powder samples were separated by species having a similar extractive content. The partial least square (PLS) method was applied to develop a calibration model for predicting chemical composition. This model showed good performance in predicting the extractive and lignin content of all species. The calibration results of the extractive and lignin content for all species were indicated as R2 = 0.99. The cross-validation of the components for all species also showed an excellent value of R2 = 0.98 and 0.97, respectively. Based on our results, it was possible to suggest a useful tool for providing rapid information about wood used in the bioenergy and pulp production fields.

  • Researchpp 2452-2472Bikár, M., Sedliačiková, M., Vavrová, K., Moresová, M., and Hitka, M. (2018). "Does the combustion of biomass increase the efficiency of heating companies? Evidence from Slovakia," BioRes. 13(2), 2452-2472.AbstractPDF

    Over the last decade, the consumption of renewable energy within the EU increased by 66%, and corporations have recognized that heating with wood waste is a cost-effective response to fluctuating fuel prices and a means of avoiding waste disposal costs. The main objective of this paper was to determine whether the combustion of biomass compared with the use of fossil fuels as the primary heat source would increase the efficiency in Slovak heating companies. This research was evaluated via methods of synthesis, analyses, and financial analyses. The survey found that heating companies with combined productions had better economic results. Based on the peer group comparison, heating companies using renewable resources achieved remarkably higher performance indicators. Among renewable energy sources, total biomass plays an important role and accounted for just over two thirds (64%) of the gross inland energy consumption of renewables in the EU. Wood pellets and agglomerates are currently the most economical way of converting biomass into fuel and are a fast-growing source of energy in Europe. The economic efficiency and key performance indicators strongly depend on the input prices of the energy carriers. In the last decade, the cost of heat produced from natural gas amounted on average to two to three times the cost of deciduous wood. Biomass production can generate employment, and if intensive agriculture is replaced by less intensively managed energy crops, there are likely to be environmental benefits, such as reduced leaching of fertilizers and reduced use of pesticides.

  • Researchpp 2473-2486Yu, Y., Jiang, X., Ramaswamy, H. S., Zhu, S., and Li, H. (2018). "Effect of high-pressure densification on moisture sorption properties of Paulownia wood," BioRes. 13(2), 2473-2486.AbstractPDF

    The effect of high-pressure (HP) densification (30, 90, and 150 MPa for 3, 30, and 300 s) on the moisture sorption properties of Paulownia wood was investigated. After the densification, samples were conditioned at three temperatures (20, 30, and 40 °C) and five equilibrium moisture contents (from 11.20 to 95.62%) during the study, after which the equilibrium moisture contents of the control and treated samples were measured. The HP-treated groups had higher equilibrium moisture contents than the controls at higher relative humidity levels. The hysteresis phenomenon and the scanning electron microscopy observations were explained by the transformation of the structural elements by the HP treatment. Finally, two moisture sorption isotherm (MSI) models (a linear polynomial model for adsorption and a quadratic polynomial model for desorption) were established with good performance to describe the relationship between HP treatment parameters, environmental conditions, and equilibrium moisture contents.

  • Researchpp 2487-2498Liang, F., Fang, G., Jiao, J., Deng, Y., Han, S., Shen, K., Shi, Y., Li, H., Zhu, B., Pan, A., and Tian, Q. (2018). "The use of twin screw extruder instead of model screw device during bamboo chemo-mechanical pulping," BioRes. 13(2), 2487-2498.AbstractPDF

    Bamboo is one of the most important raw materials for pulp and paper production in several countries due to its abundance and cost-effectiveness. However, the difficulties in bleaching and low brightness of bamboo chemo-mechanical pulp (CMP) has limited the expansion of its utilization. In this study, the low-cost twin-screw extruder (TSE) was used instead of the high-cost common extruded model screw device (MSD) before chemical impregnation to improve the brightness of the bamboo CMP. There were minor differences in the holocellulose, lignin, and pentose contents in the extruded materials between the two devices. The absorbency of the TSE extruded materials was 4.50 g/g, which was three times that of the material extruded by MSD. Alkali optimization was conducted at levels of 12% H2O2. The TSE-CMP achieved the highest brightness, at 57.6% ISO with 6% sodium hydroxide (NaOH), while the MSD-TMP only reached approximately 49.6% ISO with 3% NaOH. At the same time, the physical properties of paper-sheets made from bleached TSE-CMP and MSD-CMP were tested. When bleached at 12% H2O2 with 6% NaOH, the tensile index of TSE-CMP was higher compared with that of MSD-CMP, while the other strength properties were nearly unchanged.

  • Researchpp 2499-2514Ye, H., Zhang, Y., and Yu, Z. (2018). "Wood flour’s effect on the properties of geopolymer-based composites at different curing times," BioRes. 13(2), 2499-2514.AbstractPDF

    Fly-ash (FA) /wood-flour (WF) geopolymer composites (FWGCs) were prepared to investigate the influence of WF on the properties of FA-based geopolymer composites at different curing times. The crystallization, surface morphology, geopolymerization, interface analysis, and mechanical properties were characterized. The results indicated that the curing time exerted positive effects on the mechanical strength of the FWGCs. Noticeably distinct microstructures and mechanical properties were observed with different WF contents. The FWGCs with low WF loading (1 wt% and 5 wt%) presented almost unchanged or even improved mechanical properties compared to the pure FA-based geopolymer due to the existence of bonds between the WF and geopolymer matrix in the interface. However, the addition of WF to a higher content (10 wt%, 15 wt%, and 20 wt%) posted a negative influence on mechanical properties with insufficient polymerization of geopolymer and degradation of WF detected by morphology and elemental microanalysis. This study will facilitate a better understanding of the interaction between geopolymers and wooden materials, and serve as a basis for further research and applications.

  • Researchpp 2515-2529Kubovsky, I., Kacik, F., and Velkova, V. (2018). "The effects of CO2 laser irradiation on color and major chemical component changes in hardwoods," BioRes. 13(2), 2515-2529.AbstractPDF

    The influence of laser radiation was evaluated relative to the color and major chemical component changes of three hardwood species. The surfaces of maple (Acer pseudoplatanus L.), beech (Fagus sylvatica L.), and lime (i.e. linden, Tilia vulgaris) wood were exposed to radiation from a CO2 laser (wavelength = 10.6 µm, output power = 45 W). It was observed that increased doses of irradiation resulted in a decrease in the lightness (L*), increase in the total color difference, and a drop in the total polysaccharide content. Compared with the non-irradiated specimens, the ΔL* values at the highest irradiation doses were −56 (maple), −46.8 (beech), and −50.5 (lime). The trends observed in the FTIR spectra also showed there was a relationship between the breaking of C=O and C=C bonds in important functional groups in the lignin, hemicellulose, and carbohydrates. A highly linear correlation (R2 from 0.902 to 0.987) was observed between the increase in the ΔL* and decrease in the hemicellulose content, which degrades faster than other basic wood components. Such a phenomenon may have been related to the formation of new chromophore structures, which caused the color changes in the wood.

  • Researchpp 2530-2545Huan, Z., Jiao, Z., Li, G., and Wu, X. (2018). "Velocity error correction based tomographic imaging for stress wave nondestructive evaluation of wood," BioRes. 13(2), 2530-2545.AbstractPDF

    Stress wave testing has been applied in the nondestructive evaluation of wood for many years. However, the anisotropy property of wood and the limited number of sensors prevent an accurate stress wave velocity measurement and the high resolution of tomographic inversion. This paper proposes a tomographic imaging algorithm (IABLE) with a velocity error correction mechanism. The proposed algorithm computed the wave velocity distribution of the grid cells of wood cross-sections by the least square QR decomposition (LSQR) iterative inversion, and then optimized the tomography with a velocity error correction mechanism (ECM). To evaluate the performance of the proposed algorithm, several healthy and defective logs and live trees were selected as the experimental samples, and the nondestructive testing procedures were finished. With the stress wave velocity data sets measured via a PiCUS 3 stress wave testing instrument, the IABLE algorithm was implemented, and the tomographic images of the log samples and live trees were generated. The experimental results demonstrated the effectiveness of the proposed imaging algorithm for the nondestructive evaluation of wood.

  • Researchpp 2546-2561Gajdačová, P., Hýsek, Š., and Jarský, V. (2018). "Utilisation of winter rapeseed in wood-based materials as a solution of wood shortage and forest protection," BioRes. 13(2), 2546-2561.AbstractPDF

    Due to various factors, there is evidence that there will be a future lack of wood materials in the woodworking and energy sectors, as well as other sectors. This has been confirmed definitively through the most recent developments. Possible solutions include the partial replacement of wood in composite materials by post-harvest remnants of agricultural crops. Unlike wood matter, however, these stems need surface pre-treatment before they can be used to produce composite materials. In this study the effects were compared for two pre-treatments of stems (alkaline and hydrothermal) of rapeseed (Brassica napus L.), maize (Zea mays L.), and wheat (Triticum aestivum L.). The effects were compared using the contact angle between water and the surfaces of the stems. Hydrothermal modification yielded a statistically significant reduction in the contact angle between water and the stem surfaces of winter rapeseed and maize; likewise, alkaline modification yielded a statistically significant reduction in the contact angle between water and the stem surface of maize. The possibility of using winter rape to produce composite materials was further evaluated and comprehensively assessed using SWOT analysis.

  • Researchpp 2562-2577Long, Z., Wu, J., Xu, W., and Lin, W. (2018). "Study of the coordination mechanism of a wood processing residue-based reverse supply chain," BioRes. 13(2), 2562-2577.AbstractPDF

    A revenue-sharing contract was introduced into a three-echelon wood processing residue-based reverse supply chain model to maximize the supply chain profit and realize a win-win situation for all participants. The optimal expected supply chain profits under different decision policies and the acceptable range of revenue-sharing coefficients were analyzed. Finally, the model was applied in a case study where sawdust was recycled to produce black fungus. Results showed that revenue-sharing can effectively enable supply chain coordination. Within the domain of the revenue-sharing coefficients, the production cost decreased by 5.91% and the corresponding demand increased by 16.09%, resulting in an increase of 7.73% in the supply chain profit. A comparison was made between the three-echelon and a two-echelon supply chains, and the results showed that the two-echelon supply chain would become less competitive than the three-echelon supply chain with the increase of recycling cost. Additionally, the profit shares of all parties in the three-echelon supply chain depended mainly on the revenue-sharing coefficients, which were determined by the positions of the parties and their bargaining power.

  • Researchpp 2578-2591Yang, F., Ma, H., Tang, L., and Feng, Y. (2018). "Effect of polyvinyl alcohol treatment on mechanical properties of bamboo/polylactic acid composites," BioRes. 13(2), 2578-2591.AbstractPDF

    Polylactic acid (PLA) and bamboo fiber are both green and biodegradable materials. However, the bonding of PLA and bamboo fiber is poor, which limits the physical properties of paper. The effects of polyvinyl alcohol (PVOH) on PLA fiber/bamboo fiber composites were studied by measuring the tensile strength, tear resistance, and breaking length of the paper. In addition, the morphology of paper comprised of PLA fiber and bamboo fiber were investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The tensile index, tear index, and breaking length of paper made with the 4 wt% PVOH-treated bamboo fiber and the untreated PLA fiber compared favorably with the paper made of the untreated bamboo fiber and PLA fiber increased 21.0%, 8.6%, and 20.8%, respectively. However, compared with the paper made of the untreated bamboo fiber and PLA fiber, the tensile index, tear index, and breaking length of the paper made with the treated PLA fiber and the treated bamboo fiber with 4 wt% PVOH solution were dramatically reduced by 30%, 18%, and 30%, respectively.

  • Researchpp 2592-2601Hýsek, Š., Šedivka, P., Böhm, M., Schönfelder, O., and Beran, R. (2018). "Influence of using recycled polyurethane particles as a filler on properties of polyurethane adhesives for gluing of wood," BioRes. 13(2), 2592-2601.AbstractPDF

    Fillers can greatly affect the properties of adhesives, and this research aimed at enhancing the performance of adhesives by using different concentrations of fillers. This paper describes the influence of using recycled polyurethane particles (powder of particle size from 10 µm to 50 µm) as a filler on some properties of polyurethane adhesives for the gluing of wood. Two kinds of one-component, moisture-curing polyurethane adhesives were used. The observed properties were the contact angle between the wood and adhesive droplet, and the strength of bonded joints (shear strength). From the results, it was concluded that the contact angle increased with an increase in filler (in the entire observed range from 0% to 15% filler). The content of filler also affected the strength of bonded joints and their thermal stability. The strength of bonded joints decreased with an increase in filler content when samples were conditioned in cold water. However, the strength of bonded joints increased with an increase in filler content when samples were boiled in water.

  • Researchpp 2602-2616Pesenti, H., Zumelzu, E., Gacitua, W., Torres, M., Castillo, J., Sanchez, A., Leoni, M., and Dodoo-Arhin, D. (2018). "Characterizing Teline monspessulana as a green sustainable source of biofibers," BioRes. 13(2), 2602-2616.AbstractPDF

    Invasive Teline monspessulana can be an important source of biomass to supply fibers for the rising demand of cellulose bioproducts, especially for the development of advanced materials. Its fibers can be extracted via a thermo-alkaline process at 170 °C with 40 g/L of sodium hydroxide (NaOH) and characterized by crystallographic, thermo-analytical, and mechanical techniques. The cellulose proportion in the wood of this species is approximately 47.6 wt.% ± 1.05 wt.%. However, its fibers are relatively small, and they have a wide range of aspect ratios from 25 to 287, with an average diameter of 9.3 μm ± 2.5 μm. These characteristics and mechanical properties make the fibers unattractive for the textile and paper industries. Meanwhile, crystalline cellulose was prevalent in the monoclinic phase, with a crystalline index and crystalline portion of 78 and 41%, respectively, observing crystal domains of c.a. 3.2 nm. Nanoindentation tests revealed favorable values of elastic modulus and hardness of c.a. 16 GPa and 0.28 GPa, respectively. Thus, this bioresource is expected to see promising applications in materials engineering, such as reinforcement in material composites, in drug delivery carrier, and electronic devices, among other biomultifunctional components.

  • Researchpp 2617-2631Wang, S., Lv, M., Yang, J., Zhou, Y., and Xu, B. (2018). "Effects and mechanism of metal ions on enzymatic hydrolysis of wheat straw after pretreatment," BioRes. 13(2), 2617-2631.AbstractPDF

    The effects and mechanism on the enzymatic hydrolysis of lignocellulose by metal ions were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), Fluorescence Spectra, and enzymatic kinetics and activity analyses of the enzymatic hydrolysis system. Fe3+ exerted the best enzymatic hydrolysis effect on pretreated wheat straw, and the highest reducing sugar conversion was 44.5%. SEM and FTIR indicated that alkali and ultrasonic pretreatments partially removed the lignin and hemicellulose from lignocellulose. DLS and fluorescence spectra results revealed that the electrostatic interaction between Fe3+ and the carboxyl group in the enzyme enlarged the enzyme’s steric structure. The data on enzymatic kinetics displayed that Fe3+ increased the maximum rate of reaction by 33.9% and the Michaelis-Menten by 5.72 g/L. The enzyme activity increase rate rose initially and then diminished, and the maximum increase rate was 36.1%.