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BioResources
  • Researchpp 4191-4203Hao, W., Tang, X., Zeng, X., Sun, Y., Liu, S., and Lin, L. (2015). "Catalytic conversion of glucose to levulinate ester derivative in ethylene glycol," BioRes. 10(3), 4191-4203.AbstractArticlePDF

    A comprehensive, kinetic experiment on the conversion of glucose to 2-hydroxyethyl levulinate ethylene ketal (HLEK), in a cascade of reactions in ethylene glycol, catalyzed by low-concentration sulfuric acid, was conducted. The ethylene glycol/sulfuric acid system was found to be tolerant of a high glucose concentration, and no solid humins were created. At a high initial glucose concentration (30 wt %), an HLEK yield of 27.6% was achieved at a moderate temperature (433 K) after a 330-min reaction with dilute sulfuric acid (0.15 mol/L). In ethylene glycol, more than half of the initial glucose was converted into glucosides within 5 min, and a dynamic equilibrium between these species was achieved; thus, it is reasonable to assume that the ratio of glucosides to glucose was constant (1.35:1) during the entire reaction process. The production of HLEK from glucose via glucosides as a function of the process variables was well-represented by a simplified first-order kinetic model, and the rate expressions were applied to determine the optimum conditions for batch processing.

  • Researchpp 4204-4225Belle, J., Kleemann, S., Odermatt, J., and Olbrich, A. (2015). "Demonstration of strength development in initial wet paper web using Field Emission-Scanning Electron Microscopy (FE-SEM)," BioRes. 10(3), 4204-4225.AbstractArticlePDF

    Various models exist that explain strength development in the wet web. Furthermore the scanning electron microscope (SEM) has been used in the paper industry to characterise cellulosic fibres and paper. The documentation of the initial wet web properties needs very specific requirements for sample preparation. An SEM image shows the sample´s surface, so the wet sample’s water film would cover all fine fibre structures. For this reason the samples must be dried prior to analysis. Freeze drying is a common method that is described to prepare samples for characterisation of single fibres before and after mechanical treatment. In this investigation the structure of the initial wet web was physically fixed by rapid freezing, followed by freeze drying. Afterwards, the samples were analyzed by Field Emission SEM (FE-SEM). The generated images support the hypothesis that fibrils partially extend themselves from the fibre and interact with adjacent fibres.

  • Researchpp 4226-4238Kvietková, M., Gašparík, M., and Gaff, M. (2015). "Effect of thermal treatment on surface quality of beech wood after plane milling," BioRes. 10(3), 4226-4238.AbstractArticlePDF

    This paper deals with the determination of the surface quality of both thermally treated and thermally untreated wood after the plane milling process. The milled surface quality was evaluated on the basis of the arithmetical mean deviation of the assessed profile, Ra. Surface quality measurements were carried out for various milling process parameters, such as tool clearance angles of 15º, 20º, and 25º, cutting speeds of 20, 30, and 40 m/s, and feed speeds of 4, 8, and 11 m/min. A splinter with a uniform thickness of 1 mm was removed from the wood through milling. Based on the results, it can be stated that thermal treatment of wood has no statistically significant impact on roughness. The most significant impact of the monitored factors were associated with feed speed, clearance angle, and cutting speed. The lowest average roughness values were found at 20º clearance angles, a feed speed of 4 m/min, and a cutting speed of 40 m/s. Increases in cutting speed led to a decrease in average roughness, while an increase in feed speed had the opposite effect.

  • Researchpp 4239-4251Lv, P., Almeida, G., and Perré, P. (2015). "TGA-FTIR analysis of torrefaction of lignocellulosic components (cellulose, xylan, lignin) in isothermal conditions over a wide range of time durations," BioRes. 10(3), 4239-4251.AbstractArticlePDF

    This study investigated chemical decomposition of lignocellulosic components in the course of torrefaction under isothermal conditions for durations up to 5 hours. The goal was a better understanding of the behaviour of biomass, at both short and long residence times, which is important for innovation in the chemical and bioenergy industries. Gaseous and solid-phase decomposition products of cellulose, xylan, and two lignins, were studied following torrefaction at three temperatures (220, 250, and 280 °C) for a continuous recording of mass loss and emission of volatiles over 5 hours. Two decomposition stages were revealed for xylan, with a notable release of CO that increased with treatment temperature. 4-O-methyl glucurono-units on the side chains of xylan degraded first, and acetyl groups and macromolecule fragments accounted for the second degradation, starting at 250 °C. The primary production of acetic acid occurred at 280 °C. For the two lignins, decomposition reactions predominated at lower temperatures, while rearrangement prevailed at 280 °C. The emission of phenol was a clear distinction between the two. Cellulose was thermally stable at short times under all treatments, but it decomposed dramatically afterwards, especially at 280 °C.

  • Researchpp 4252-4262Zhang, Y., Yang, R., Wu, Y., Wang, S., Liu, C., Zhong, X., and Wu, J. (2015). "Effect of growth period on cell wall mechanical properties of elephant grass," BioRes. 10(3), 4252-4262.AbstractArticlePDF

    Elephant grass (Pennisetum purpureum Schum.) is a fast-growing native African plant species that produces commercially useful lignocellulosic biomass. It has been used in many countries to replace wood for paper, particleboard, and fiberboard. There is a close relationship between the mechanical properties of elephant grass cell walls and the performance of its products. The objective of this research was to investigate the cell wall mechanical properties at different growth periods of five types of elephant grasses, i.e., P. americanum cv. Tift 23A×P. purpureum cv. Tift N51 (HP), P. purpureum cv. Tift N51 (N51), P. purpureum cv. Huanan (Huanan), P. purpureum cv. Sumu No.2 (Sumu-2), and (P. americanum× P. purpureum) × P. purpureum cv. Guimu No.1 (Guimu-1). The hardness and elastic modulus of the cell walls were investigated by means of nanoindentation. The results showed that the hardness and elastic modulus of these elephant grasses increased as growth period increased. However, the rate of increase varied for the different types of elephant grass, which could help guide the evaluation of the properties of this kind of bio-fiber resource for the production of high-quality biocomposite products.

  • Researchpp 4263-4276Xian, Y., Li, H., Wang, C., Wang, G., Ren, W., and Cheng, H. (2015). "Effect of white mud as a second filler on the mechanical and thermal properties of bamboo residue fiber/polyethylene composites," BioRes. 10(3), 4263-4276.AbstractArticlePDF

    The purpose of this study was to investigate the effect of white mud (WM) on mechanical and thermal properties of bamboo plastic composites (BPCs). Bamboo residue fibers (BRFs) and WM were added as the reinforcement, and high-density polyethylene (HDPE) served as the matrix. The lubricating agent and coupling agent were polyethylene wax and maleated polyethylene (MAPE), respectively. The mixture was used to manufacture BPCs using a twin-screw extruder. The crystal structure and thermal properties of BPCs were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the particle size of the WM was 700 nm to 50 μm, which are made mainly of calcium carbonate. BPCs with WM significantly increased the flexural and tensile properties, but the impact strength decreased because of the presence of WM. The flexural and tensile strength of composites with 18 wt% BPF were increased by 36.81% and 6.26%, respectively, while the flexural and tensile modulus were increased by 164.29% and 64.33%, respectively. XRD demonstrated the WM had little effect on the crystal structure of BPCs. Compared to BPCs without WM, the T5% of composites with 22 wt% WM decreased by 27.9 °C. As the WM content increased, the crystallinity of the BPCs decreased initially, then increased with increasing WM content.

  • Researchpp 4277-4286Zhou, X., Wang, X., Cao, R., Tao, Y., Xu, Y., and Yu, S. (2015). "Characteristics and kinetics of the aldonic acids production using whole-cell catalysis of Gluconobacter oxydans," BioRes. 10(3), 4277-4286.AbstractArticlePDF

    The characteristics and kinetics of whole-cell catalysis were investigated individually or simultaneously relative to the bio-oxidation of five monosaccharides to corresponding aldonic acids using Gluconobacter oxydans. For individual catalysis, 30 g/L glucose could be consumed completely at 3.21 g/L/h in 8 h, and arabinose was the slowest-consumed at 1.18 g/L/h in 8 h. Among five monosaccharides, the yield of xylonic acid was highest at 90.4%, and about 31.0 g/L xylonic acid could be obtained in 24 h. For simultaneous catalysis, a complex substrate competition appeared in the mixed-aldoses solution. The utilization rate of arabinose, galactose, xylose and mannose were repressed distinctly. And glucose exhibited variable inhibitory effects on the remaining four monosaccharides utilization. Higher concentration of mixed aldoses showed a tendency to minimize the difference of glucose inhibition on arabinose, galactose, xylose, and mannose conversion to corresponding acids. Thus, the total concentration and proportion between various aldoses should be properly controlled for a highly efficient production of aldonic acids from lignocellulosic material.

  • Researchpp 4287-4299Sha, J., Nikbakht, A., Wang, C., Zhang, H., and Olson, J. (2015). "The effect of consistency and freeness on the yield stress of chemical pulp fibre suspensions," BioRes. 10(3), 4287-4299.AbstractArticlePDF

    To study the influence of mechanical treatments on the yield stress of chemical pulp suspensions, a traditional rheometer, coupled with local velocity measurements (ultrasonic Doppler velocimetry), was used to measure the yield stress of two types of commercial chemical pulp suspensions with different freeness values at mass concentrations (consistencies) ranging from 0.5 to 1.5%. Over the range of consistencies tested, the yield stress was found to depend on the consistency through a power law relationship for all tested samples. Moreover, the results showed that as the freeness decreased, the yield stress of hardwood suspensions increased to a maximum value then decreased. This variation in yield stress was also observed in softwood suspensions with mass concentrations above 1%. However, when the consistency was lower than 0.75%, the yield stress of softwood suspensions increased with decreasing freeness.This behaviour can be understood based on the underlying fibre properties of fibrillation, curl, and stiffness, suggesting that fibre morphology plays a significant role on the yield stress of pulp suspensions over the concentration range studied.

  • Researchpp 4300-4314İlçe, A. C., Budakçı, M., Özdemir, S., and Akkuş, M. (2015). "Analysis of usability in furniture production of wood plastic laminated board," BioRes. 10(3), 4300-4314.AbstractArticlePDF

    The objective of this study was to manufacture a lightweight and easily producible wood plastic laminate (WPL) board that could be used in the furniture sector. Eastern beech (Fagus orientalis L.) veneer papels (A) and hollow polycarbonate boards (B), both with a thickness of 4 mm, were laminated in different combinations using polyurethane (PUR) and polychloroprene (PCR) adhesives. The physical and mechanical properties of the WPL boards obtained were determined according to the principles specified in the EN 326-1, EN 317, EN 310, ASTM D1037, and ASTM D1761 standards. Subsequently, the specimens were compared with particle boards (PB), medium density fiberboards (MDF), and okoume plywoods (PW). According to the results, the AABAA, ABABA, and ABBBA combinations of the WPL materials had better physical properties, such as weight, water absorption, and swelling thickness, compared to the other composites. Furthermore, because the WPL materials had a high bending resistance, modulus of elasticity, and nail and screw withdrawal strength, they could be used instead of PB and MDF. The WPL material obtained within the scope of this study are suitable for furniture making.

  • Researchpp 4315-4325Zhu, J., Xue, L., Wei, W., Mu, C., Jiang, M., and Zhou, Z. (2015). "Modification of lignin with silane coupling agent to improve the interface of poly(L-lactic) acid/lignin composites," BioRes. 10(3), 4315-4325.AbstractArticlePDF

    To improve the mechanical properties of lignin-filled poly(L-lactic) composites, three silane coupling agents, 3-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltrimethoxysilane (KH560), and g-methyacryl-oxypropyltrimethoxysilane (KH570), were treated systematically with different solvents to modify the interfacial connections. The treatment of lignin with 2 wt.% aqueous KH550 solution was proved to be the most successful. Chemical bonding between the filler and the matrix was formed, according to the FTIR spectra. Furthermore, scanning electron microscope images showed that such treated lignin particles dispersed well in the composites. The tensile strength and Young’s modulus of the composite improved significantly from 55.1 and 1589 MPa to 67.0 and 1641 MPa, respectively, with 5 wt.% treated lignin addition. Although its elongation at break decreased from 20.3 to 12.4% after 5 wt.% of the treated lignin was added, it was still better than that of poly(L-lactic acid) without any additive (10.3%).

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