NC State
  • Researchpp 88-103Fernández-Puratich, H., Oliver-Villanueva, J. V., Alfonso-Solar, D., and Peñalvo-López, E. (2013). "Quantification of potential lignocellulosic biomass in fruit trees grown in Mediterranean regions," BioRes. 8(1), 88-103.AbstractArticlePDF

    This research was based on three species: Citrus sinensis (orange), Olea europaea (olive), and Prunus amygdalus (almond). The biomass was determined for a complete tree without roots, but including stem, branches, and canopy or crown. The obtained results demonstrate that the stem volume is slightly higher for almond trees (0.035 m3/tree) than for olive trees (0.027 m3/tree). In comparison, the average stem volume of orange trees is lower (0.006 m3/tree). On the other hand, the total biomass volume including canopy branches is similar in all three species: 0.043 m3/tree for orange tree, 0.066 m3/tree for olive tree, and 0.040 m3/tree for almond tree. The new practical quantification model for these Mediterranean agricultural crops is based on total biomass calculations normally used in forestry stands. So, the obtained values were used to develop models for biomass of the stem, branches, and canopy, relating them with the diameter and volume stem. The regression analysis shows a significant correlation with minimized estimation errors. This allows a practical use of this model in biomass calculation in standing trees, both for total tree biomass and also for pruning material.

  • Researchpp 104-114Xu, X., Lee, S., Wu, Y., and Wu, Q. (2013). "Borate-treated strand board from southern wood species: Resistance against decay and mold fungi," BioRes. 8(1), 104-114.AbstractArticlePDF

    Combined decay and mold resistance of zinc borate-(ZB) and calcium borate-(CB) treated oriented strand board (OSB) from southern mixed hardwood (MHW) and southern yellow pine (SYP) was investigated. Tests were done with a brown-rot fungus, Gloeophyllum trabeum, and a white-rot fungus, Trametes versicolor, for 8 and 12 weeks, respectively. Wood species and fungus type had significant influence on the decay resistance. Decay caused by the brown-rot fungus was evident for all untreated SYP and mixed MHW controls. White-rot fungus did not cause significant sample weight loss for either species group. In the SYP OSB control inoculated with G. trabeum, the hyphae were abundant in wood rays and cell walls where they primarily penetrated through bordered and simple pits. The incorporation of ZB and CB into OSB provided significant protection against the fungi with no significant weight loss observed in the treated OSB. Microscopic analysis showed distinct evidence of fungal colonization and a thinning pattern of cell wall material. Untreated OSB samples from MHW and commercial OSBs were most susceptible to mold growth after 6 weeks. The borate-modified OSB from MHW and SYP effectively prevented the mold growth.

  • Researchpp 115-129Hunt, J. F., Zhang, H., Guo, Z., and Fu, F. (2013). "Cantilever beam static and dynamic response comparison with mid-point bending for thin MDF composite panels," BioRes. 8(1), 115-129.AbstractArticlePDF

    A new cantilever beam apparatus has been developed to measure static and vibrational properties of small and thin samples of wood or composite panels. The apparatus applies a known displacement to a cantilever beam, measures its static load, then releases it into its natural first mode of transverse vibration. Free vibrational tip displacements as a function of time were recorded. This paper compares the test results from the cantilever beam static bending and vibration with standard mid-point simply supported bending samples. Medium density fiberboard panels were obtained from four different commercial sources. Comparisons were made using a set of fiberboard panels with thicknesses of 8.1, 4.5, 3.7, and 2.6 mm and nominal densities of 700, 770, 780, and 830 kg/m3, respectively. Cantilever beam static modulus and dynamic modulus of elasticity linearly correlated well but were consistently higher than standard mid-point bending modulus of elasticity having linear correlations of 1.12:1 and 1.26:1, respectively. The higher strain rates of both the static and vibrating cantilever beam could be the primary reason for the slightly higher dynamic modulus values. The log decrement of the displacement was also used to calculate the damping ratio for the cantilever beam. As expected, damping ratio had a slightly decreasing slope as density increased. This paper discusses the new apparatus and initial results.

  • Researchpp 130-144Liang, X., Zhang, Y., Liu, L., and Yao, J. (2013). "Synthesis and urea-loading of an eco-friendly superabsorbent composite based on mulberry branches," BioRes. 8(1), 130-144.AbstractArticlePDF

    Mulberry branch, consisting of bark and stalk, was used as raw skeleton material without any chemical pre-treatment to synthesize an eco-friendly mulberry branch-g-poly(acrylic acid-co-acrylamide) (PMB/P(AA-co-AM)) superabsorbent composite. The synthesis conditions and properties of the PMB/P(AA-co-AM) superabsorbent composite were investigated. The results showed that under the optimal synthesis conditions, the water absorbency of the prepared PMB/P(AA-co-AM) reached 570.5 g/g in deionized water, 288.0 g/g in tap water, and 70.0 g/g in 0.9 wt% aqueous NaCl solution. The PMB/P(AA-co-AM) composite also exhibited excellent water retention capacity as well as a rapid water absorbency rate. The urea loading percentage of the PMB/P(AA-co-AM) composite was controlled by the concentration of aqueous urea solution. The release of urea from the loaded PMB/P(AA-co-AM) composite in deionized water initially exhibited a high rate of release for 60 min, followed by a rapid decline. Meanwhile, the PMB/P(AA-co-AM) superabsorbent composite with larger particle size achieved a better sustanined release of urea.

  • Researchpp 145-157Irshad, M., Anwar, Z., But, H. I., Afroz, A., Ikram, N., and Rashid, U. (2013). "The industrial applicability of purified cellulase complex indigenously produced by Trichoderma viride through solid-state bio-processing of agro-industrial and municipal paper wastes," BioRes. 8(1), 145-157.AbstractArticlePDF

    An indigenous strain of Trichoderma viride produced high titers of cellulase complex in solid-state bio-processing of agro-industrial orange peel waste, which was used as the growth-supporting substrate. When the conditions of the SSF medium containing 15 g orange peel (50% w/w moisture) inoculated with 5 mL of inoculum were optimal, the maximum productions of endoglucanase (655 ± 5.5 U/mL), exoglucanase (412 ± 4.3 U/mL), and β-glucosidase (515 ± 3.7 U/mL) were recorded after 4 days of incubation at pH 5 and 35 °C. The enzyme with maximum activity (endoglucanase) was purified by ammonium sulfate fractionation and Sephadex G-100 column gel filtration chromatographic technique. Endoglucanase was 5.5-fold purified with specific activity of 498 U/mg in comparison to the crude enzyme. The enzyme was shown to have a molecular weight of 58 kDa by sodium dodecyl sulphate poly-acrylamide gel electrophoresis (SDS-PAGE). The shelf life profile revealed that the enzyme could be stored at room temperature (30 °C) for up to 45 days without losing much of its activity.

  • Researchpp 158-171Santos, R. B., Jameel, H., Chang, H.-M., and Hart, P. W. (2013). "Impact of lignin and carbohydrate chemical structures on degradation reactions during hardwood kraft pulping processes," BioRes. 8(1), 158-171.AbstractArticlePDF

    Most studies aimed at determining rates of hardwood delignification and carbohydrate degradation have focused on understanding the behavior of a single wood species. Such studies tend to determine either the delignification rate or the rate of carbohydrate degradation without examining the potential interactions resulting from related variables. The current study provides a comprehensive evaluation on both lignin and carbohydrate degradation during kraft pulping of multiple hardwood species. The kraft delignification rates of E. urograndis, E. nitens, E. globulus, sweet gum, maple, red oak, red alder, cottonwood, and acacia were obtained. Furthermore, the kinetics of glucan, xylan, and total carbohydrate dissolution during the bulk phase of the kraft pulping process for the above species were also investigated. The wide ranges of delignification and carbohydrate degradation rates were correlated to wood chemical characteristics. It appears that the S/G ratio and lignin-carbohydrate-complexes (LCCs) are the main characteristics responsible for the differences in kraft pulping performance among the hardwoods studied.

  • Researchpp 172-181Chi, C., Chang, H.-M., Li, Z., Jameel, H., and Zhang, Z. (2013). "A method for rapid determination of sugars in lignocellulose prehydrolyzate," BioRes. 8(1), 172-181.AbstractArticlePDF

    A simple and rapid dual-wavelength spectroscopic method is used for simultaneous determination of pentoses and hexoses in the prehydrolyzate from lignocellulosic biomass. The method is based on the following reaction mechanism: in the solution of hydrochloric acid, phloroglucinol gives color reaction with sugars or their degradation products, showing maximum absorbance at 553 nm and 410 nm. Based on dual-wavelength spectrophotometric measurement, the pentoses and hexoses can separately be quantified. It was found that the derivatives from these two different sugars have an isosbestic point at 425 nm. According to the validation results, high accuracy and reasonable recovery rate is shown with the present method (pentoses recovery 97.1 to 100.0%, hexoses recovery 97.2 to 102.0%). Additionally, the interferences from substances including lignin, furfural, 5-hydroxymethyl furfural (HMF), glucuronic acid, and galacturonic acid are insignificant. All of the above results illustrate the suitability of this method for analyzing sugars in the lignocelluloses prehydrolyzate, especially hardwoods or herbaceous plants, based on forest-related biorefinery research.

  • Researchpp 182-188Zhou, Q., Tu, D., Liao, L., and Guo, Q. (2013). "Variation of equilibrium moisture content of heat-treated Couratari oblongifolia, Fraxinus excelsior, and Quercus rubra wood," BioRes. 8(1), 182-188.AbstractArticlePDF

    Heat treatment may result in variation of wood equilibrium moisture content (EMC). During this study, tauari (Couratari oblongifolia), ash (Fraxinus excelsior), and oak (Quercus rubra) woods were heat-treated at 190, 200, and 210ºC for 3 hours and then put into a conditioning chamber with a temperature from 30 to 75ºC and a relative humidity from 50 to 90%. The isothermal moisture adsorption curve was subsequently analyzed. Results indicated that the EMC of heat-treated wood was reduced by 23.4 to 37.4% compared to non-treated wood, but the EMC difference at different heat-treated temperatures for three hardwoods was quite small and the EMC of heat-treated wood was inversely proportional to their dry density.

  • Researchpp 189-200Li, Z., Liu, C., Qin, M., Fu, Y., and Gao, Y. (2013). "Stickies control with pectinase for improving behavior of cationic polymers in a mixture of chemithermomechanical pulp and deinked pulp," BioRes. 8(1), 189-200.AbstractArticlePDF

    In this work, a pressure-sensitive adhesive (PSA) was used as the model substance for secondary stickies. The dissolved and colloidal substances (DCS) prepared from bleached chemithermomechanical pulp (BCTMP) and the effects of pectinase treatment on the stickies deposition were evaluated. The results showed that the addition of DCS lowered the efficiency of cationic polymers and aggravated the deposition of stickies. As a major component of anionic DCS, polygalacturonic acids can be effectively degraded during pectinase treatment. Therefore, the efficiency of cationic polymers improved, and subsequently they were able to fix the destabilized sticky particles on the fibers, which led to the decrease of stickies deposition. However, the pectinase treatment of DCS insignificantly affected stickies deposition in absence of cationic polymers when the stickies deposition was caused by calcium ions.

  • Researchpp 201-210Eshraghi, A., Khademieslam, H., Ghasemi, I., and Talaiepoor, M. (2013). "Effect of weathering on the properties of hybrid composite based on polyethylene, woodflour, and nanoclay," BioRes. 8(1), 201-210.AbstractArticlePDF

    Hybrid composites of polyethylene/wood flour/nanoclay with different concentrations of nanoclay were fabricated using melt compounding followed by injection molding. Composites were weathered in a xenon-arc type accelerated weathering apparatus for 2000 h. Physical properties of the composites were evaluated by colorimetery and water absorption before and after weathering. Changes in surface chemistry were monitored using spectroscopic techniques. The results indicated that water absorption of the composites increased after weathering, but nanoclay can reduce the intensity of weathering to some extent by decreasing water absorption. Weathering increased the degree of color change and lightness of the samples; however, the lightness of the samples containing nanoclay was less than that of neat wood-plastic composites. Fourier transform infrared spectroscopy revealed a lower carbonyl index of composites containing nanoclay. X-ray diffraction patterns revealed that the nanocomposites formed were intercalated. The order of intercalation for samples containing 2 wt% nanoclay was higher than that of 4 wt% at the same maleic anhydride grafted polyethylene content, due to some agglomeration of the nanoclay.