NC State
  • Researchpp 4730-4743Ekevad, M., and Axelsson, A. (2012). "Variation of modulus of elasticity in the tangential direction with moisture content and temperature for Norway spruce (Picea abies)," BioRes. 7(4), 4730-4743.AbstractArticlePDF

    Modulus of elasticity (MOE) in the tangential direction for Norway spruce, Picea abies (L.) H. Karst, was measured. Test samples were tested in three-point bending, and moisture content (MC) and temperature were varied between the green condition and 7% MC and between 20 °C and 80 °C, respectively. Using correction factors calculated from finite element simulations, an adjustment of measured MOE was made to the ideally tangential direction. The results show MOE and the gradients with respect to MC and temperature and how they vary with MC and temperature. The gradients are factors in gradient terms in the incremental stress-strain relation for linear elastic behaviour during load cycles where there are mechanical loads and at the same time, varying MC and temperature. The gradient terms add to the temperature and MC expansion coefficients and may be of significant size for cases with high stress, high temperature, and high MC.

  • Researchpp 4744-4759Peng, F., Bian, J., Peng, P., Guan, Y., Xu, F., and Sun, R.-C. (2012). "Fractional separation and structural features of hemicelluloses from sweet sorghum leaves," BioRes. 7(4), 4744-4759.AbstractArticlePDF

    Six hemicellulosic samples were isolated from cell wall material of dewaxed sweet sorghum (Sorghum bicolor (L.) Moench) leaves by sequential extractions with distilled water, alkali, and organic alkali solvent. The samples were treated with water, 1% NaOH, and 60% ethanol. The organic alkali samples were treated with 1%, 3%, 5%, and 8% NaOH, which yielded 8.3%, 5.4%, 1.0%, 5.6%, 2.5%, and 4.9% hemicelluloses based on the dry initial sweet sorghum leaves, respectively, and resulted in a total release of 81% of all hemicelluloses originally present in the cell wall. The results indicated that water-soluble hemicelluloses contained noticeable amounts of glucose, arabinose, galactose, and xylose, and had a relatively lower molecular weight (17300 g/mol). The four alkali-soluble hemicellulosic fractions, rich in xylose, were more linear, and had higher molecular weights (48500-128000 g/mol) than those of the alkali organic-soluble hemicellulosic fraction. With an increase of NaOH concentration from 1% to 8%, the ratio of arabinose to xylose decreased from 0.29 to 0.01, which implied that the hemicelluloses obtained by the higher concentration of alkali appeared to be more linear. Based on the sugar analysis, Fourier transform infrared (FT-IR), and nuclear magnetic resonance (NMR) results, 4-O-methylglucuronoarabinoxylans were the major constituents of the hemicellulosic polymers.

  • Researchpp 4760-4775Shamsuri, A. A., and Daik, R. (2012). "Plasticizing effect of choline chloride/urea eutectic-based ionic liquid on physicochemical properties of agarose films," BioRes. 7(4), 4760-4775.AbstractArticlePDF

    Agarose films were formed with the addition of 30 to 70 wt% choline chloride/urea eutectic-based ionic liquid (ChCl/Urea). The ChCl/Urea was prepared through complexation at a 1:2 mole ratio. The films were prepared by dissolving ChCl/Urea in distilled water followed by dispersion of the agarose at 95 °C. The solution was gelled at room temperature, and the formed gel was dried in an oven overnight at 70 °C. Mechanical testing indicated that the agarose film containing 60 wt% ChCl/Urea had higher tensile extension and tensile strain at break compared to the pristine agarose film. The addition of ChCl/Urea also reduced the glass transition temperature (Tg) of agarose films. Cross-section SEM images of the agarose films showed that surface roughness disappeared with the incorporation of ChCl/Urea. FTIR spectra confirmed the presence of intermolecular hydrogen bonding between agarose and ChCl/Urea. XRD patterns demonstrated that an amorphous phase was obtained when ChCl/Urea was added. Agarose films containing more ChCl/Urea exhibited higher transparency, as measured by a UV-Vis spectrometer. In summary, the physicochemical properties of agarose films were evidently affected by the incorporation of the ChCl/Urea as a plasticizing agent.

  • Researchpp 4776-4785Zhou, X., Zheng, F., Liu, X., Tang, L., Xue, G., Du, G., Yong, Q., Chen, M., and Zhu, L. (2012). "Glass transition of oxygen plasma treated enzymatic hydrolysis lignin," BioRes. 7(4), 4776-4785.AbstractArticlePDF

    This study investigated the effect of oxygen plasma treatment on the glass transition temperature of enzymatic hydrolysis lignin (EHL) derived from the production of bio-ethanol. Differential scanning calorimetry (DSC) was used to obtain the glass transition temperature (Tg) of EHL. The results showed that the Tg value of EHL under different heating rates ranged from 160 to 200 °C, and there was a strong linear correlation between heating rate and Tg. The Tg value of oxygen plasma treated EHL decreased when compared with the untreated samples. The apparent Tg of the untreated sample was 168.2 °C, while the value of the treated sample was 161.5 °C. Distinct chain scission and introduction of oxygen-based functional groups on the surface of EHL were detected by XPS analysis. These changes may occur mainly on the bulky side chain and thus enhance molecular mobility of EHL. This indicates that oxygen plasma treatment can modify the structure and improve the reactivity of EHL efficiently.

  • Researchpp 4786-4805Wan Razali, W. A., Baharuddin, A. S., Talib, A. T., Sulaiman, A., Naim, M. N., Hassan, M. A., and Shirai, Y. (2012). "Degradation of oil palm empty fruit bunches (OPEFB) fibre during composting process using in-vessel composter," BioRes. 7(4), 4786-4805.AbstractArticlePDF

    Changes in the lignocellulosic structure of oil palm empty fruit bunches (OPEFB) during composting treatment using an in-vessel composter was investigated in this work. The composting process was completed within 40 days of treatment, and the final C/N ratio achieved was 13.85. Scanning electron microscopy (SEM) revealed that the structure of OPEFB material was severely degraded, especially during the thermophilic phase where the biodegradation process was most active. Close examination of the physicochemical and thermal analysis using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermogravimetric and differential thermal analysis (TG/DTA) showed that the crystallinity size of the OPEFB structure decreased. This result was attributed to the removal of silica bodies from OPEFB materials. Also, the functional groups of cellulose, hemicelluloses, and lignin structures had changed throughout the composting period, and the most extensive degradation of cellulose was detected in the thermophilic phase. It was also found that the exothermic peak of the matured compost reduced most significantly compared to the raw OPEFB. In conclusion, the in-vessel composting system was able to enhance the degradation process of OPEFB materials for producing compost.

  • Researchpp 4806-4816Jiang, Z., Chen, F., Wang, G., Liu, X., Shi, S. Q., and Cheng, H. T. (2012). "The circumferential mechanical properties of bamboo with uniaxial and biaxial compression tests," BioRes. 7(4), 4806-4816.AbstractArticlePDF

    The objective of this study was to investigate the effect of uniaxial and biaxial compression loadings on the circumferential-radial mechanical properties of bamboo. A novel biaxial testing device, called the 3D composite material analysis system, was developed to conduct biaxial compression tests. Strain field analysis was characterized with the help of the digital speckle correlation method (DSCM). The effects of four different environmental treatments (I. air-drying, II. constant temperature and relative humidity, III. relatively low temperature, and IV. ultra-low temperature) on the circumferential performance of bamboo were examined in the experiment. The results of this study indicated that the diametric strength of bamboo evaluated by biaxial load was as 2.4 to 2.5 times the uniaxial compression. Under biaxial load, the strength of the bamboo node was about 2.38 times higher than the internode. Failure first occurred at the outside surface of bamboo at about the 45° position between X and Y axial when conducting a biaxial compression test. The distribution of X-strain field expressed itself more uniformly than the Y-strain field. The diametric mechanical properties of bamboo ring were σIV>σIII>σII>σI for both the uniaixal and biaxial compression tests.

  • Researchpp 4817-4842Pirraglia, A., Gonzalez, R., Denig, J., Saloni, D., and Wright, J. (2012). "Assessment of the most adequate pre-treatments and woody biomass sources intended for direct co-firing in the U.S.," BioRes. 7(4), 4817-4842.AbstractArticlePDF

    There is increasing interest in replacing coal with woody biomass in co-firing plants for electrical power. A variety of pre-treatments can be used to make biomass more suitable for co-firing. This research presents a model that evaluates the delivered costs of various pre-treated biomass sources, electricity production costs, and constraints, and calculates a least cost mix. Results of the scenario presented indicate that wood chips are the most economical co-firing option for delivering biomass to direct-fired boilers. Apart from potential feeding and processing issues, the wood-chips options of forest residues present the lowest cost of electricity production for small-scale co-firing applications. From the options that will ensure minimum processing issues in the co-firing cycle, wood pellets from southern yellow pine represent the most economical choice. Based on coal displacement from the facility, torrefied wood pellets from southern yellow pine is a preferred option as compared to other choices evaluated. An alternative to torrefied wood pellets from southern yellow pine is dark torrefied Eucalyptus benthamii, providing similar electricity production costs while reducing coal utilization.

  • Researchpp 4843-4857Şen, A., Olivella, M. À., Fiol, N., Miranda, I., Villaescusa, I., and Pereira, H. (2012). "Removal of chromium (VI) in aqueous environments using cork and heat-treated cork samples from Quercus cerris and Quercus suber," BioRes. 7(4), 4843-4857.AbstractArticlePDF

    Chromium (VI) removal and its reduction to chromium (III) from aqueous solution by untreated and heat-treated Quercus cerris and heat-treated Quercus suber black agglomerate cork granules was investigated. Initial screening studies revealed that among the sorbents tested, untreated Q. cerris and Q. suber black agglomerate are the most efficient in the removal of Cr(VI) ions and were selected for adsorption essays. Heat treatment adversely affected chromium adsorption and chromium (VI) reduction in Q. cerris cork. The highest metal uptake was found at pH 3.0 for Q. cerris and pH 2.0 for black agglomerate. The experimental data fitted the Langmuir model and the calculated qmax was 22.98 mg/g in black agglomerate and 21.69 mg/g in untreated Q. cerris cork. The FTIR results indicated that while in black agglomerate, lignin is the sole component responsible for Cr(VI) sorption, and in untreated Q. cerris cork, suberin and polysaccharides also play a significant role on the sorption. The SEM-EDX results imply that chromium has a homogenous distribution within both cork granules. Also, phloemic residues in Q. cerris granules showed higher chromium concentration. The results obtained in this study show that untreated Q. cerris and black agglomerate cork granules can be an effective and economical alternative to more costly materials for the treatment of liquid wastes containing chromium.

  • Researchpp 4858-4866Basturk, M. A. (2012). "Heat applied chitosan treatment on hardwood chips to improve physical and mechanical properties of particleboard," BioRes. 7(4), 4858-4866.AbstractArticlePDF

    High-heat treatment after surface application of chitosan was used in an effort to improve physical and mechanical performances of particleboard. Particleboard is mainly used in the furniture industry and also used as a home decoration material; however, it has a poor dimensional stability. In this work, hardwood chips were obtained from a commercial plant; half of the chips were used for the control panels without chitosan treatment, and the other half were treated with chitosan acetate solutions (2% wt). Those chitosan-treated particles were also exposed to extra high-heat (140°C) treatment for 90 minutes to convert chitosan acetate back to chitin. Liquid phenol-formaldehyde resin was sprayed onto dry particles at a level of 6 and 7% (wt) based upon oven-dry weight. The mat was pressed (200°C) for 11 minutes to form 19 mm thickness and a target of 0.63 g cm-3 density panels. Thickness swelling, linear expansion, and water gain of the treated panels were reduced over untreated panels during a 24-hour water-soak test. In addition, chitosan-treated panels showed better internal bond strength than control panels. Static bending test results showed a negative effect for the chitosan treated particleboard.

  • Researchpp 4867-4874Behjou, F. K., and Ghafarzade Mollabashi, O. (2012). "Selective logging and damage to unharvested trees in a hyrcanian forest of Iran," BioRes. 7(4), 4867-4874.AbstractArticlePDF

    Selective logging in mature hardwood stands of Caspian forests often causes physical damage to residual trees through felling and skidding operations, resulting in a decline in bole quality and subsequent loss of tree value. This study evaluated the logging damage to residual trees following logging operations. A total density of 5.1 trees/ha and 17.3 m3/ha of wood were harvested. On average, 9.8 trees were damaged for every tree extracted, including 8 trees destroyed or severely damaged. The most common types of damage included uprooted stems, stem wounds to the cambial layer, and bark scrapes. Damage to trees sustained along skid trails was found to be significantly more than the damage that incurred within logging gaps and winching areas. The results of this study suggest that logging practices also need to be accompanied by close supervision of field personnel and post-logging site inspections to be implemented properly.