NC State
  • Editorialpp 1-2Wang, P., Qian, X., and Shen, J. (2018). "Superhydrophobic coatings with edible biowaxes for reducing or eliminating liquid residues of foods and drinks in containers," BioRes. 13(1), 1-2.AbstractArticlePDF

    Biowaxes, including carnauba wax and beeswax, are edible and renewable. Once dispersed in a polar solvent, these natural materials could be easily converted into nontoxic, “roll-off”, and superhydrophobic coatings on the basis of spray coating. The combination of container materials with these coatings can reduce or even eliminate liquid resides (including highly viscous residues) of foods and drinks in containers (e.g., bottles), significantly facilitating downstream operations. Comprehensive demonstrations of this green concept would generate huge opportunities for food/drink-related industries.

  • Editorialpp 3-5Zhu, S., Yang, M., Luo, F., Yang, X., and Xue, Y. (2018). "Engineering cell wall-degrading enzymes into growing plants to improve lignocellulosic ethanol production," BioRes. 13(1), 3-5.AbstractArticlePDF

    The plant cell wall (PCW) represents the most abundant renewable biomass resource for lignocellulosic ethanol production. Economical and efficient degradation of PCW to fermentable sugars is an essential sub-process during lignocellulosic ethanol production. At present, the recalcitrance of PCW to various pretreatments and enzymatic hydrolysis makes the PCW degradation unacceptably expensive. Engineering cell wall-degrading enzymes into growing plants provides a promising solution to lower the PCW degradation cost and increase its degradation efficiency for lignocellulosic ethanol production. Avoiding damage by the expressed biomass-degrading enzymes to growing plants is the key to successful use of this method. Two modern biological technologies can be used to solve this problem. One is to engineer a thermoregulated intein-modified cell wall-degrading enzyme into growing plants. The other is to use the gene-timed expression technique. This editorial will give a brief discussion of opportunities and challenges of engineering cell wall-degrading enzymes into growing plants for improvement of lignocellulosic ethanol production.

  • Researchpp 6-14Wu, H., Yang, X., Rao, J., Zhang, Y., and Sun, F. (2018). "Improvement of bamboo properties via in situ construction of polyhydroxyethyl methylacrylate and polymethyl methylacrylate networks," BioRes. 13(1), 6-14.AbstractPDF

    The chemical modification of bamboo culm was explored based on in situ construction of polyhydroxyethyl methylacrylate (PHEMA) and polymethyl methylacrylate (PMMA) networks into the cell walls. Scanning electron microscopy revealed that the synthesized polymers distributed in both the cell walls and the lumen with the pits blocked. The dimensional stability was tested under three water soaking-drying and moistening-drying cycles. The swelling efficiency of the treated bamboo was under 8% in three cycles of water soaking and drying cycles and was 4% in moistening-drying cycles. The anti-swelling efficiency was 60.5%, 52.7%, and 46.3%, respectively, in the moistening-drying cycles. Laboratory tests on mold resistance showed that no mycelium formed on the treated bamboo, while the untreated control was 100% covered by mold fungi.

  • Researchpp 15-26Avci, E., Acar, M., Gonultas, O., and Candan, Z. (2018). "Manufacturing biocomposites using black pine bark and oak bark," BioRes. 13(1), 15-26.AbstractPDF

    Bark as a biowaste has a huge availability throughout the world and has had limited use in industrial applications. Black pine bark and oak bark were considered in this work. The aim was to manufacture a new biocomposite with different combination of black pine bark, oak bark, polypropylene, polyethylene, and a coupling agent, and to determine some physical and mechanical properties of the manufactured biocomposites. Density, thickness swelling, water absorption, tension strength, modulus of rapture and modulus of elasticity in bending and tension of the biocomposites were determined. According to the results, thickness swelling and water absorption properties were improved up to 80% when compared with wood-plastic composites (WPC) produced with wood flour. Although the new biocomposites displayed lower mechanical performance in comparison of biocomposites made with wood flour, the observed results were satisfactory. Based on the results of this study, black pine bark and oak bark can be used as filler materials in WPCs production. Hereby, these bark materials can be the raw material for value-added products. Bark use in biocomposite production also can contribute to reduced requirements of wood material and petroleum products.

  • Researchpp 27-42Li, J., Wang, B., Chen, K., Tian, J., Zeng, X., Xu, J., and Gao, W. (2018). "Optimization of pretreatment and alkaline cooking of wheat straw on its pulpability using response surface methodology," BioRes. 13(1), 27-42.AbstractPDF

    The dissolution rates of the chemical compositions of alcohol-benzene extractables (ABE), holocellulose, hemicellulose, and lignin in wheat straw (WS) under different pretreatment conditions were investigated. The individual and interactive effects of three independent parameters, namely, sodium hydroxide (NaOH) dosage (x1: 8 wt.% to 12 wt.%), sodium sulfide (Na2S) dosage (x2: 10 wt.% to 18 wt.%), and time to maximum temperature (x3: 100 min to 140 min) on screened yield, Kappa number, and brightness of wheat straw pulp (WSP) were analyzed via response surface methodology (RSM). The results suggested that the quadratic equations were in good agreement with the experimental figures in the present work. The relative errors of verification results were less than 5%, which indicated that the selected model for explaining the relationship between the variables and the responses was correct. In addition, the relationships between the screened yield, reject yield, brightness, and Kappa number were described and explained. Wheat straw pulpability was optimized in this study via RSM.

  • Researchpp 43-52Hamdan, S., Abdul Wahid, H., Musoddiq, I., and Yohanes, N. (2018). "Marimba instrument construction from kayu malam wood (Diospyros maingayi)," BioRes. 13(1), 43-52.AbstractPDF

    This work investigated the possibility of using a local wood Kayu malam (Diospyros maingayi) to construct a marimba, a musical instrument. The marimba was constructed as similar as possible to the commercial rosewood marimba. The sound and established frequencies were compared with a commercial rosewood marimba. The findings showed that although the peak value of the spectrum from the prototype marimba differs from pitch to pitch, it is useful to note that the prototype marimba was tuned according to piano standard. The commercial marimba only has peaks at the lower end of the spectrum whereas the prototype marimba contained peaks up until the higher end of its spectrum. The marimba made of Kayu malam (D. maingayi) produced the same pitch as the marimba made of rosewood.

  • Researchpp 53-70Inwood, J. P. W., Pakzad, L., and Fatehi, P. (2018). "Production of sulfur containing kraft lignin products," BioRes. 13(1), 53-70.AbstractPDF

    Kraft lignin is produced in great quantities in many countries, but is mainly used as an energy source. To valorize its potential end-use applications, softwood kraft lignin was modified via sulfuric acid and sodium sulfite treatments in this study. The modification of kraft lignin through a sulfuric acid treatment resulted in a modified lignin (SA-lignin) with a charge density of 0.8 meq/g but with a limited water solubility. The sulfonation of the kraft lignin through a sodium sulfite treatment induced a soluble sulfonated lignin (SS-lignin) with a charge density of 1.4 meq/g, which was obtained under the conditions of 90 °C, 4 h, and 0.67 Na2SO3/lignin molar ratio. The elemental compositions, molecular weights, and thermal and rheological properties of modified lignin samples were characterized.

  • Researchpp 71-85Wang, Q., Xiao, S., Shi, S., and Cai, L. (2017). "Mechanical strength, thermal stability, and hydrophobicity of fiber materials after removal of residual lignin," BioRes. 13(1), 71-85.AbstractPDF

    The behaviors of the mechanical, hydrophobic, and thermal properties of the molded fiber product (MFP) were examined after the removal of residual lignin. The fibers resulting from the chemi-thermomechanical pulping and bleaching processes were treated by extended delignification, namely by their reaction with glacial acetic acid and sodium chlorite. The changes in surface composition, chemical structure, crystallinity, microstructure, and thermal stability of the MFP were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), respectively. Results showed that the composition and structure of carbohydrates on the fiber surface were not changed significantly, the lignin in fibers was almost completely removed, the relative content of intermolecular hydrogen bonds in cellulose and the contact area between fibers was increased, and the crystallinity index increased from 79.5% to 81.4% after the extended delignification. When the content of lignin decreased from 5.78% to 0.02%, the tensile strength of the MFP increased 25.6%, but little changes were found in the bending strength. The onset thermal decomposition temperature of MFP increased from 242 °C to 250 °C and the maximum rate of degradation temperature increased from 347 °C to 350 °C.

  • Researchpp 86-103Ramnath, L., Sithole, B., and Govinden, R. (2018). "The effects of wood storage on the chemical composition and indigenous microflora of Eucalyptus species used in the pulping industry," BioRes. 13(1), 86-103.AbstractPDF

    Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at -20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at -20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at -20 °C.

  • Researchpp 104-114Částková, T., Hýsek, Š., Sikora, A., Schönfelder, O., and Böhm, M. (2018). "Chemical and physical parameters of different modifications of rape straw (Brassica napus L.)," BioRes. 13(1), 104-114.AbstractPDF

    Material alternatives to wood, such as rape straw, are needed for the production of composite materials. This study performed an analysis of rape straw as a composite material source for production. There were three types of rape straw particle modification: untreated particles as reference variant, boiling in water, and soaking in sodium hydroxide (NaOH) solution. The pH and calorific value were highest for the variant soaked in NaOH. The total elemental content and the elements on the rape straw surface varied between variants. The modification method chosen influenced the pH, calorific value, elemental composition, and contact angle.

  • Researchpp 115-130Lee, C. S., Aroua, M. K., Wan Daud, W. A., Cognet, P., Pérès, Y., and Ajeel, M. A. (2018). "Selective electroreduction of glycerol to 1,2-propanediol on a mixed carbon-black activated carbon electrode and a mixed carbon black-diamond electrode," BioRes. 13(1), 115-130.AbstractPDF

    1,2-propanediol was selectively produced by electroreduction of glycerol in a two-compartment reactor. Two new kinds of cathode electrodes were evaluated: (i) mixed carbon black-activated carbon electrodes and (ii) mixed carbon black-diamond electrodes. These electrodes were compared with a conventional platinum electrode. With a reaction temperature of 80 °C, an electric current of 2.0 A, and ambient pressure, the mixed carbon black-activated carbon electrode demonstrated excellent performance and successfully reduced glycerol to 1,2-propanediol with a high selectivity of 86% and 74% glycerol conversion.  The selectivity of 1,2-propanediol on the mixed carbon black-diamond electrode and the platinum electrode was 68% and 61%, respectively, with 88% glycerol conversion on the mixed carbon black-diamond electrode and 67% glycerol conversion on the platinum electrode. The authors propose a possible reaction mechanism for the formation of 1,2-PDO.

  • Researchpp 131-146Zhou, A., Bian, Y., Shen, Y., Huang, D., and Zhou, M. (2018). "Inelastic bending performances of laminated bamboo beams: Experimental investigation and analytical study," BioRes. 13(1), 131-146.AbstractPDF

    Laminated bamboo (LB) is a processed bamboo-based composite fabricated by gluing bamboo strips under controlled temperature and pressure. It has many superior mechanical properties compared to commonly used wood products and is well suited for use as a construction material. The present work consisted of two parts. The first part aimed at studying the bending performances of LB beams. The stress-strain relationship of the LB composite had approximately perfect elasticity under tension, yet exhibited more complicated behavior under compression (i.e., linearity in the prior-proportional limit and nonlinearity in the post-proportional limit). The strength in tension was significantly higher than that during compression. Damage of LB beam began with the fiber yielding in the compressive zone until failure occurred when the fibers at the outermost part of the tensile zone broke. Hence, LB beams always underwent a long nonlinear process before failure. An empirical stress-strain relationship was proposed on the basis of a bilinear model. In the second part of the study, an analytical model for calculating the load-carrying capacity and deflection of LB beams was developed. Experimental results confirmed that the model had enough accuracy for design calculation.

  • Researchpp 147-156Köse Demirel, G., Güdül, H., Temiz, A., Kuştaş, S., and Aydın, İ. (2017). "Effect of alkyl ketene dimer on the physical, mechanical, and biological durability of plywood," BioRes. 13(1), 147-156.AbstractPDF

    The effect of alkyl ketene dimer (AKD) on plywood properties was studied. AKD is widely used in the paper industry as a sizing agent and can esterify wood cell wall components. Two types of veneers obtained from alder (Alnus glutinosa subsp. barbata (C. A. Mey) Yalt.) and beech (Fagus orientalis L.) wood logs were used. Two different treatment processes and two different concentrations (1% and 3%) of AKD were tested. The first method was AKD-dispersion, which was mixed with glue and sprayed onto veneers. The second method was dipping veneers into the AKD solutions (1% and 3%) for 25 min. Water uptake after 2 h, 24 h, and 48 h was reduced by the AKD treatment. Plywood produced from AKD impregnated veneers showed the lowest thickness swelling versus untreated plywood and plywood produced from AKD blended in glue. The AKD treatment generally reduced the mechanical properties of the plywood. However, AKD treatment considerably improved the biological resistance against brown rot fungi (Coniophera puteana BAM Ebw. 15) and white rot fungi (Trametes versicolor CTB 863A). Increased methyl/methylene and carbonyl groups of the alkyl chain were determined in the Fourier transform infrared (FTIR) spectra of specimens subjected to the AKD-dispersion method.

  • Researchpp 157-170Čabalová, I., Kačík, F., Lagaňa, R., Výbohová, E., Bubeníková, T., Čaňová, I., and Ďurkovič, J. (2018). "Effect of thermal treatment on the chemical, physical, and mechanical properties of pedunculate oak (Quercus robur L.) wood," BioRes. 13(1), 157-170.AbstractPDF

    Changes in the chemical composition and selected physico-mechanical properties of pedunculate oak (Quercus robur L.) wood samples were assessed after thermal treatment. Heat treatment was performed at 160, 180, and 200 °C in an oxidizing atmosphere. The contents of the extractives, lignin, cellulose, holocellulose, and saccharides, and the structural changes in the functional groups were determined. Changes in the colour traits, wood density, compression strength parallel to the grain, and compression modulus of elasticity were also determined. The decrease in the holocellulose content caused by the degradation of non-glucosic saccharides was observed during thermal treatment. The contents of both the extractives and lignin increased. The syringyl to guaiacyl (S/G) ratio in the lignin increased because of the preferential condensation of guaiacyl units. The physical and mechanical properties of pedunculate oak wood, such as density, equilibrium moisture content, colour lightness, and yellowness, decreased as the temperature increased. The compression strength and redness varied during thermal treatment, and reached maximum values during the treatment at 180 °C. The modulus of elasticity showed non-significant differences. Three groups of heat treatment clusters were distinguished in the multivariate wood trait analysis and were clearly segregated from each other.

  • Researchpp 171-175Mitchell, P. (2018). "Calculating the equilibrium moisture content for wood based on humidity measurements," BioRes. 13(1), 171-175.AbstractPDF

    If given enough time, the moisture content of wood will reach an equilibrium with its surrounding environment. The temperature and relative humidity (RH) of the surrounding air will establish equilibrium moisture content (EMC) conditions, and the moisture content of the wood in that environment will approach a value determined by the RH. This article introduces an Excel spreadsheet that will calculate an estimate of the EMC based on any one of the following three pairs of data: RH and dry-bulb temperature, wet-bulb temperature and dry-bulb temperature, or dew-point temperature and dry-bulb temperature.

  • Researchpp 176-191Morais, I. L. H., Silva, C. M., Zanuncio, J. C., and Zanuncio, A. J. V. (2018). "Structural stabilization of granular sludge by addition of calcium ions into aerobic bioreactors," BioRes. 13(1), 176-191.AbstractPDF

    Granulation is a gradual process that makes flocculent sludge granular through the simultaneous densification and selection of aggregates via sedimentation. The damage to the granule structure over time in a bioreactor operation is one of the most severe barriers to the practical application of the process. The addition of metal ions may increase aggregation rates and granular structure stability. Four sequential batch reactors fed with pulp mill effluent were operated and monitored. Three reactors contained aerobic granular sludge and one contained flocculent sludge. One granular sludge SBR received the addition of 100 mg∙L-1 of Ca2+, the second 200 mg∙L-1 of Ca2+, and the third received no intentional addition of calcium. The fourth SBR was operated with conventional flocculent sludge. The efficiency of the organic matter removal and the effect of calcium on the morphological characteristics of the granules formed were evaluated. The removal efficiency of the COD and the BOD was similar among all SBR, i.e., 60% and 90%, respectively. The addition of calcium did not interfere with granule size. The addition of 100 mg∙L-1 of Ca2+ increased the uniformity and the mechanical strength of the granules. It also increased approximately 36% of the settling velocity of the granules.

  • Researchpp 192-207Dang, C., Yin, Y., Xu, M., and Pu, J. (2018). "Hydrophobic noncrystalline porous starch (NCPS): Dispersed silver nanoparticle suspension as an antibacterial coating for packaging paper," BioRes. 13(1), 192-207.AbstractPDF

    Hydrophobic noncrystalline porous starch (NCPS) containing microporous and amorphous structures was prepared from native corn starch via heat treatment, solvent exchange, and alkyl ketene dimer (AKD) modification. Then, antibacterial packaging was produced by combining silver nanoparticles with the hydrophobic NCPS (hydrophobic NCPS/Ag) and employing this biobased coating as a layer on the base paper. The antibacterial activity, strength, and barrier properties of the hydrophobic NCPS/Ag-coated paper were measured. In addition, the fine porous surface of NCPS, the distribution of the silver nanoparticles in hydrophobic NCPS as well as the network structure of uncoated paper and coated paper were characterized by scanning electron microscopy. Meanwhile, the hydrophobicity of the corn starch, hydrophobic NCPS, uncoated paper, and coated paper were determined using water contact angles. The silver nanoparticles had a positive effect on the antibacterial activity against Escherichia coli and Staphylococcus aureus. The air permeability, oil resistance, water vapor transmission rate, water absorption, whiteness, tensile strength, and burst strength improved compared to the uncoated paper.

  • Researchpp 208-219Yoshioka, K., Yamada, T., Ohno, H., and Miyafuji, H. (2018). "Production of furan compounds from Cryptomeria japonica using pyridinium chloride under various conditions," BioRes. 13(1), 208-219.AbstractPDF

    Cryptomeria japonica was treated with pyridinium chloride ([Py]Cl)-water mixtures under various conditions to determine the optimum conditions for efficient production of furan compounds, such as 2-hydroxyacetylfuran (2-HAF), 5-hydroxymethylfurfural (5-HMF), and furfural. The maximum total yield of furan compounds, i.e., 9.24 wt.%, was obtained by the treatment of C. japonica with a 90% [Py]Cl and 10% water (w/w) solution for 30 min at 120 °C with a sample loading of 6 wt.%. The highest yield of 2-HAF from C. japonica was obtained by treatment for 3 min at 160 °C without the addition of water, although the total yield of furan compounds was lower than that obtained under the optimum treatment conditions. Scale-up of this process for efficient production of furan compounds from C. japonica was successfully performed under the optimum treatment conditions. In addition, the yields of 2-HAF and 5-HMF increased when ball-milled C. japonica containing low-crystallinity cellulose was treated under the optimum conditions.

  • Researchpp 220-230Lin, H., Sun, M., Li, J., Xu, Q., Yang, B., Wang, Q., Xie, W., Sun, S., Hu, K., and Zhang, L. (2018). "Purification and characterization of xylanase from spent mushroom compost and its application in saccharification of biomass wastes," BioRes. 13(1), 220-230.AbstractPDF

    The activities of xylanase extracted from spent mushroom composts (SMCs) of Coprinus comatus, Auricularia auricular, Pleurotus ostreatus, Pleurotus citrinopileatus, Agrocybe cylindracea, Hericium erinaceus, Hypsizygus marmoreus, and Tremella fuciformis were investigated. The crude extract from T. fuciformis SMC showed high xylanase activity with a value of 255.2 U/mg. Furthermore, this xylanase was purified using a combination of ammonium sulfate precipitation, diethylaminoethyl-cellulose (DEAE-cellulose), and gel filtration column chromatography. The enzyme was purified 20.7-fold with a yield of 43.1% and activity of 5293.8 U/mg. The purified xylanase showed maximum activity at 50 °C and pH 6, retained 80% activity after 1 h incubation at 50 °C, and sustained stability over a wide range of pH values (2 to 10). Under the optimal conditions, the enzyme exhibited a Km value of 2.5 mg/mL towards birchwood xylan. The activity of xylanase was enhanced in the presence of Mg2+, Ca2+, Ba2+, NH4+, and Tween 80, while some metal ions, particularly Fe3+, inhibited its activity. The saccharification of several biomass wastes using the crude xylanase enzyme was studied. The results showed the potential for saccharification of alkaline-pretreated wheat bran solution where 75% saccharification was achieved.

  • Researchpp 231-240Wu, W., Jiang, B., Yang, L., and Jin, Y. (2018). "Isolation of lignin from Masson pine by liquid-liquid extraction based on complete dissolution in NaOH aqueous solution," BioRes. 13(1), 231-240.AbstractPDF

    A method for lignin isolation from softwood based on complete dissolution in NaOH aqueous solution and liquid-liquid extraction was introduced. The structural features of milled alkali-soluble lignin (MAL) were comparatively analyzed with those of classical milled wood lignin (MWL) by means of alkaline nitrobenzene oxidation (NBO) and molecular weight, as well as Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectra analyses. The results showed that the yield of crude MAL (34.2%) was about twice as much as that of MWL (16.4%). The NBO product yields of MWL and MAL were quite similar. The weight-average molecular weight of MAL (10,400 g mol-1) was much higher than for MWL (6,970 g mol-1). Both MWL and MAL displayed similar FTIR, UV, 1H NMR, and 1H-13C HSQC NMR spectra. The total OH content of MAL (4.48 mmol g-1) was higher than that of MWL (3.89 mmol g-1). Compared with MWL, MAL showed similar structural characteristics but better isolation yield and higher molecular weight.

  • Researchpp 241-255Lee, J., Kim, S., Sim, K., Kang, D., and Youn, H. J. (2018). "Application of inorganic particles modified with polyvinylamine to produce antibacterial paper," BioRes. 13(1), 241-255.AbstractPDF

    Antibacterial activity is one of the desired functionalities in paper and board grades, especially for packaging. This study designed a contact-active antibacterial surface using polyvinylamine (PVAm) bonded onto inorganic particles (kaolin), and investigated appropriate ways to utilize the treated inorganic particles as antibacterial carriers to produce antibacterial paper. Antibacterial inorganic particles were prepared by modifying the surface of kaolin through a polyelectrolytes multilayering (PEM) technique with a PVAm and polyacrylic acid system. The pH control during the PEM process affected the adsorption amount of PVAm and dispersion stability of PEM-treated kaolin. The PEM-treated kaolin was applied to prepared handsheets via two ways, internal addition or surface treatment. Only the surface-treated handsheets had a noticeably reduced bacteria ratio. Antibacterial activity was > 99.9% for Escherichia coli and > 99% for Listeria monocytogenes. The inactivation of bacteria with damaging membranes was confirmed by a dual staining method. The surface coverage of the PEM kaolin on the handsheets was an important factor for inactivation of the bacteria. As a result, the surface treatment of antibacterial inorganic particles was determined to be the proper strategy to produce antibacterial paper.

  • Reviewpp to be addedHubbe, M., Pizzi, A., Zhang, H., and Halis, R. (2018). "Critical links governing performance of self-binding and natural binders for hot-pressed reconstituted lignocellulosic board without added formaldehyde: A review," BioRes. 13(1), Pg #s to be added.AbstractPDF

    The production of fiberboard, particleboard, and related hot-pressed biomass products can convert small, relatively low-valued pieces of wood into valuable products. There is strong interest in being able to manufacture such products without the addition of formaldehyde, which is a health hazard during both production and use.  This article reviews literature describing various challenges that need to be faced in order to achieve satisfactory bonding properties in hot-pressed bio-based board products without the addition of formaldehyde.  Bonding mechanisms are examined in the form of a hypothesis, in which the strength development is represented by a chain with four links.  Failure of a board is expected to occur at the weakest of these mechanistic links, which include mechanical contact, molecular-scale wetting and contact, various chemical-based linkages, and structural integrity.  The most promising technologies for environmentally friendly production of hot-pressed board with use of lignocellulosic materials tend to be those that favor success in the development of at least three of the mechanistic links in the hypothetical chain.

  • Researchpp 256-271Kılıç, H., Kasal, A., Kuşkun, T., Acar, M., and Erdil, Y. (2018). "Effect of tenon size on static front to back loading performance of wooden chairs in comparison with acceptable design loads," BioRes. 13(1), 256-271.AbstractPDF

    The effects of tenon size were investigated relative to the front to back loading performance of Scots pine (Pinus sylvestris L.) chairs. Forty-five chair frames were constructed with mortise and tenon joints with 9 tenon sizes. Joints were assembled with a 65% solids polyvinyl acetate (PVAc) adhesive. The front to back loading performance of chairs was compared to the acceptable design load levels given in the American Library Association (ALA) specifications. Chair frames were structurally analyzed with the Finite Element Method (FEM) to obtain the moment acting on each joint under loading. The results indicated that a chair became stronger as either tenon width or length increased, but was most affected by its length. As a result of structural analyses, front leg to side rail and back leg to side rail joints carried approximately 73% of the total moment that was induced under the front to back loading. According to the comparison results with acceptable design loads, chairs constructed with 40 mm × 50 mm tenons could meet light service (domestic usage), while the chairs constructed with 50 mm × 50 mm tenons could meet medium service. The chairs constructed with other sizes could not meet any acceptable levels, and thus need reinforcement.

  • Researchpp 272-289Muniyadi, M., Ng, T. Y. S., Munusamy, Y., and Ooi, Z. X. (2018). "Mimusops elengi seed shell powder as a new bio-filler for polypropylene-based bio-composites," BioRes. 13(1), 272-289.AbstractPDF

    Mimusops elengi seed shell powder (MESSP) was introduced as a new bio-filler in polypropylene (PP). The MESSP was characterized using a particle size analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and a thermogravimetric analyzer. MESSP was successfully melt mixed with polypropylene to produce bio-composite at various MESSP loading. The processability and properties of the bio-composites were characterized by using processing torques, differential scanning calorimetry, tensile test, water absorption, and SEM. The processability of PP was not affected by the addition of MESSP, which was revealed from the minimum changes in the processing torques, melting temperature, crystallization temperature, and degree of crystallinity. The tensile strength and elastic modulus of the bio-composites were improved with an addition of MESSP of up to 10 wt.%. However, the elongation at break and resistance to water absorption decreased slightly with increased MESSP loading. Morphological observations revealed that the MESSP showed good dispersion and adhesion in the PP matrix of up to 5 wt.% MESSP. Above 5 wt.% MESSP, agglomerates formed, which influenced the physical-mechanical properties of the PP and MESSP bio-composites. Results indicated that PP/MESSP composites can be used to replace PP in applications such as car dashboards and door panel, furniture, and rigid packaging.