NC State
  • Researchpp 2094-2102Lukmandaru, G. (2015). "Chemical characteristics of teak wood attacked by Neotermes tectonae," BioRes. 10(2), 2094-2102.AbstractArticlePDF

    The teak trees in certain areas of Java Island are frequently attacked by Neotermes tectonae termites. Trees attacked by this species have a tumor-like growth in the stem that can be easily identified in the field. This study evaluated the chemical properties of the attacked wood. Based on a visual inspection, the type of attacks were classified as either type I, if included phloem was formed in the heartwood, or type II, which was distinguished by the softened and hollowed areas in the heartwood. For each type, three trees were cut along with a healthy tree for comparison. Comparison among type I, type II, and normal tree tissues showed huge differences in hemicellulose and extractive contents, composition of ethanol-toluene soluble extracts, ash/acid insoluble ash contents, and pH values. Comparing the two types of abnormalities along the radial direction, significant differences were observed in the cellulose contents. The lowest values of both sugars were obtained in the soft part of type II. Further, the levels of ethanol-toluene soluble extracts and their fractions (mainly low-polarity fractions) were affected by the radial direction. No significant differences in radial direction were found in the inorganic materials levels or in pH values.

  • Researchpp 2103-2112Choudhary, S. J., Mehmood, S., Naz, H., Jaafar, H. Z. E., and Zia-Ul-Haq, M. (2015). "Effect of sulfuric acid on pretreatment of YSS-10R variety of sorghum and analysis of its interaction with temperature and time," BioRes. 10(2), 2103-2112.AbstractArticlePDF

    Considering the possible threats to the oil supply due to the rapid depletion of oil reservoirs and the negative environmental impacts of petroleum use, developing an environmentally friendly biofuel such as bioethanol is needed. Pretreatment is a critical step in the production of lignocellulosic bioethanol. In this study, the effect of sulfuric acid on the pretreatment of the YSS-10R variety of sorghum was evaluated. Response Surface Methodology (RSM) was employed to develop an experimental design matrix and evaluate the effect of pretreatment parameters on the release of fermentable sugars. Sorghum straw was treated with sulfuric acid concentrations of 0.5, 1.75, and 3% (V/V) at temperatures of 70, 100, and 130 °C for reaction times of 10, 20, and 30 min. The maximum glucose yield was 7.66 g/L (0.064 g/g) and was obtained via pretreatment with 0.5% H2SO4 at 100 °C for 10 min. That of xylose was 7.62 g/L (0.064 g/g), obtained via pretreatment with 0.50% H2SO4 at 130 °C for 20 min. The pretreatment conditions for maximum xylose yield were determined to be 2% H2SO4, 130 °C, and 20 min. Results indicate that sulfuric acid is an efficient catalyst for pretreatment at high temperatures and relatively long reaction times.

  • Researchpp 2113-2129Malakani, M., Bazyar, B., Talaiepour, M., Hemmasi, A. H., and Ghasemi, I. (2015). "Effect of acetylation of wood flour and MAPP content during compounding on physical properties, decay resistance, contact angle, and morphology of polypropylene/wood flour composites," BioRes. 10(2), 2113-2129.AbstractArticlePDF

    The effects of acetylation of wood flour with vinylacetate and the content of Maleic Anhydride Polypropylene (MAPP) coupling agent before compounding were evaluated relative to water absorption and thickness swelling. Hot water was used to extract materials of sawdust fir flour before acetylation. Fir flour was successfully acetylated using vinylacetate (VA) in the presence of potassium carbonate. The modification was confirmed by the weight percent gain (18.8%) and Fourier transform Infrared (FTIR) spectroscopy. The acetylated or control wood flour was mixed with MAPP coupling agent (0, 3, & 6 wt%) at 60 rpm and 160 °C, followed by extrusion. The wood plastic composite (WPC) was made by hot pressing at 200 °C and 25 MPa for 5 min. Specimens were exposed to white-rot decay for 16 weeks. In addition to the weight loss due to fungal treatment, water absorption, thickness swelling, and contact angle of the acetylated and decayed samples was investigated. Increasing the percentage of MAPP was found to decrease the percentage of weight loss, water absorption, and thickness swelling in all of the samples. In contrast, increasing the MAPP percentage increased the contact angle in all samples. The SEM micrographs revealed that the bonding between fibers and polymeric material was improved and strengthened by MAPP addition.

  • Researchpp 2130-2142Yang, X., Li, S., Xia, J., Song, J., Huang, K., and Li, M. (2015). "Renewable myrcene-based UV-curable monomer and its copolymers with acrylated epoxidized soybean oil: Design, preparation, and characterization," BioRes. 10(2), 2130-2142.AbstractArticlePDF

    An innovative myrcene-based ultraviolet curable vinyl ester monomer was synthesized, and its molecular structure was analyzed with Fourier transform infrared spectroscopy and nuclear magnetic resonance (1HNMR and 13CNMR) analysis. A series of copolymers were also prepared by mixing the myrcene-derived monomer with another vinyl ester monomer, acrylated epoxidized soybean oil, under ultraviolet light. The curing process was monitored using Fourier transform infrared spectroscopy. Ultraviolet curing analysis showed that all the mixed systems had high curing rates and were fully cured within the first 30 seconds. When the weight ratio of myrcene-derived monomer to acrylated epoxidized soybean oil was 50/50, the ultimate double bond conversion reached 94.08%. Dynamic mechanical analysis showed that the storage modulus and glass transition temperature of the cured resins both increased with increasing content of myrcene vinyl ester monomer because the molecular structure of myrcene-derived vinyl ester monomer was more rigid and stronger than that of acrylated epoxidized soybean oil. Thermogravimetric analysis indicated that the main thermal initial decomposition temperatures were all above 360 °C, demonstrating that the copolymers had modest thermal stability.

  • Researchpp 2143-2155Obradovic, J., Fardim, P., Lassila, L., Navard, P., and Kronlund, D. (2015). "High-pressure treatment of DMAc/LiCl swollen softwood pulp," BioRes. 10(2), 2143-2155.AbstractArticlePDF

    Swollen softwood cellulose pulp in a DMAc/LiCl solvent system was compressed under elevated pressure (up to 900 MPa) in a Bridgman anvil press. The influence of high pressure on two cellulose systems was studied by measuring X-ray diffraction, mechanical and optical properties and observing scanning electron micrographs of the morphology. Compressed swollen cellulose, washed with distilled water, had lower elastic modulus and hardness compared to swollen cellulose washed with a combination of 2-propanol and deionized water. This work showed that material with lower mechanical properties will be affected more by compression and will result in higher mechanical properties after pressure treatment. Transmitted light in the visible range for both systems was increased after elevated pressure was applied. The XRD measurements revealed the decrease of the cellulose crystallinity after high pressure treatment for all swollen cellulose samples. The morphology of the compacted samples showed noticeable differences between the compact smooth surface and the layered core.

  • Researchpp 2156-2166Reixach, R., Puig, J., Méndez, J. A., Gironès, J., Espinach, F. X., Arbat, G., and Mutjé, P. (2015). "Orange wood fiber reinforced polypropylene composites: Thermal properties," BioRes. 10(2), 2156-2166.AbstractArticlePDF

    A major drawback of natural-based composites is the incorporation of reinforcements that are less thermally stable than the matrix; therefore, the thermal properties of the resultant composite material needs to be studied. In this work, orange wood fibers were used to reinforce polypropylene. The effects on the thermal properties of the polymeric matrix were analyzed. To this end, differential scanning calorimetry (DSC), thermogravimetry (TGA), thermomechanical analysis (TMA), and dynamic-mechanical analysis (DMA) were performed. It was found that the degradation of the material took place in two distinct phases: the reinforcement, close to 250 °C, and the matrix, above 340 °C. DSC results showed that fiber reinforcement did not influence the transition temperatures of the materials, although it did affect the polymer crystallinity value, increasing by 7% when the composite is reinforced with 50% of the lignocellulosic reinforcement. The coefficient of expansion obtained by TMA indicated that thermal expansion decreased as the amount of reinforcement increased. DMA assays showed that the reinforcement did not modify the glass transition (20 to 25 °C) temperature and confirmed that the addition of reinforcement increased the crystallinity of the product.

  • Researchpp 2167-2176Yu, X., Zhu, X., Gu, Z., and Lai, S. (2015). "Antioxidant activity in vivo and in vitro of two feruloyl oligosaccharides preparations produced from wheat bran and fermented by Aureobasidium pullulans," BioRes. 10(2), 2167-2176.AbstractArticlePDF

    The antioxidant functions of two feruloyl oligosaccharide (FO1 and FO2) were investigated in vivo and in vitro. Effects of FO1 and FO2 on hemolysis of rat red blood cell (RBC) and malondialdehyde (MDA) formation in rat liver homogenate and rat liver mitochondria in vitro were studied. Hemolysis of rat RBC and MDA formation in rat liver homogenate and rat liver mitochondria were inhibited in a dosage-dependent manner by FO1 and FO2 in the tested concentration range of 0.5 to 10 mg/mL. The results showed that FO1 and FO2 had antioxidative activity in vitro, and the effect of FO2 was better than that of FO1. With increasing dosage, FO1 and FO2 could increase the activity of SOD and GSH-Px in serum of S180 tumor-bearing mice, reduce the level of MDA, and thus improve the activity of the antioxidant in vivo. When the dosage reached 250 mg/kg/d, FO2 was more likely to improve the capabilities of the antioxidants of tumor-burdened mice than were 5-FU and FO1 in vivo.Thus, these oligosaccharides may be used as functional biological materials produced from fermented lignocellulose of WB.

  • Researchpp 2177-2184Ji, X., Liu, S., Wang, Q., Yang, G., Chen, J., and Fang, G. (2015). "Wet oxidation pretreatment of wood pulp waste for enhancing enzymatic saccharification," BioRes. 10(2), 2177-2184.AbstractArticlePDF

    Effective pretreatment of wood pulp waste is important for enhancing enzymatic saccharification. For this reason, wet oxidation process conditions were considered with the hypothesis that the alkaline oxygen conditions would favor delignification and hydrolysis of lignocellulose. Enzymatic saccharification was greatly improved to 42.9% in terms of reducing sugar yield under the conditions of pH = 10, oxygen pressure = 1.2 MPa, time = 15 min, and temperature = 195 °C. A total of 39% of lignin and 73% of hemicellulose were removed and dissolved into the hydrolyzate. Furthermore, the chemical structure, crystallinity, and morphology of the treated substrate were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM).

  • Researchpp 2185-2194Qin, J., Qin, Z., Yin, X., Zeng, Q., and Zhu, L. (2015). "Synthesis and characterization of alkylated bacterial cellulose in an ionic liquid," BioRes. 10(2), 2185-2194.AbstractArticlePDF

    Bacterial cellulose was alkylated by alkyl halide in the ionic liquid 1-butyl-3-methylimmidazolium chloride ([Bmim]Cl) with NaH as the alkaline agent. The derivatives were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analyses, X-ray diffraction, and thermal gravimetric analyses. The resultant bacterial cellulose alkylated derivatives (BCADs) had a degree of substitution (DS) between 0.21 and 2.01. The effects of the alkylating agent, reactant amount, and temperature on the DS were investigated. BCADs with a butyl substituent had a higher DS than did those with ethyl or propyl groups. The crystallinity and thermal stability of the derivatives decreased after modification owing to the change in morphological structure.

  • Researchpp 2213-2222Chen, Q., Guo, X., Ji, F., Wang, J., Wang, J., and Cao, P. (2015). "Effects of decorative veneer and structure on the thermal conductivity of engineered wood flooring," BioRes. 10(2), 2213-2222.AbstractArticlePDF

    This paper explores the thermal conductivity of engineered wood flooring, which is widely used in world market. The effects of decorative veneer type and structure on the thermal conductivity of engineered wood flooring were studied. Four decorative veneer types and three different structures of engineered wood flooring served as test specimens. All samples were placed in a laboratory simulating a heating system environment, of which the temperature should be measured three times every five minutes. The temperature differences between the upper and lower surfaces were as follows: cherry > maple > birch > eastern black walnut. Three types of structures also showed differences in temperature changes, based on five-minute observations. The larger the decorative veneer’s density, the higher the thermal conductivity, and the faster the heat transferred, meaning less heat was lost. The thermal conductivity of three-layer engineered wood flooring, with decorative veneer made of sawn wood, exhibited the best properties. The second best of the three samples was the three-layer engineered wood flooring with decorative veneer made of thick veneer and plywood. Finally, a multilayered engineered wood flooring performed the worst. The engineered wood flooring for use in heating systems should be chosen for its larger density of decorative veneer made of sawn wood.


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