Research Articles

An equivalent strain method was used to analyze and determine material relaxation properties for specimens from particleboard, high density fiberboard, and medium density fiberboard. Cantilever beams were clamped and then deflected to 11 m and held for either 2 h or 3 h, while the load to maintain that deflection was measured vs. time. Plots of load relaxation for each specimen showed similar load relaxation vs. time even though there were some slight differences in the maximum load per sample. Three models were developed to fit the relaxation data. The first model was a simple log decrement. This simple log model used only one variable, the relaxation coefficient, to describe the relaxation behavior as the log of time. The log decrement model was marginal at best in modeling the relaxation data. The second and third models, however, used equivalent strain methods. The second model assumed a combined linear-elastic spring and a Kelvin-Voigt spring-dashpot model. The third model used a combination of a linear-elastic spring (linear strain) element, a Kelvin-Voigt (spring-dashpot, visco-elastic strain) element, and a dashpot (permanent strain) element for its total configuration. Both equivalent strain models provided excellent correlations for the two lengths of time used for this series. Estimated mechanical and relaxation, or creep properties, were determined from the equivalent strain method using cantilever beam equations.

Bamboo (Sinocalamus affinis) lignophenols (Lps), synthesized using a phase separation system, were used as a natural plasticizing additive to complex with pulp (short fiber and fluffy short fiber) sheets. The structural features of Lps were analyzed by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy, and proton-nuclear magnetic resonance (1H-NMR). The pulp sheet absorptivity of Lps, as well as the physical properties of complex sheets, were discussed. Results showed that when the concentration of bamboo Lps solution was 10 g/L, the absorption amount of Lps in the sheets made up of short pulp fibers (12%) was slightly higher than that of sheets made of fluffy short pulp fibers (10%), whilephysical properties, such as tightness, tensile strength, elongation, bursting, and tearing, were improved obviously after the addition of Lps. More obvious improvement in the physical strength was found in sheets made up of fluffy short pulp fibers. Results indicated that the amount of absorbed Lps was of the same importance as the properties of the pulp fibers. It is necessary to adjust the properties of both the Lps and sheets to get the best mechanical strength for the pulp sheets.

This is the first report of the potential of Acacia fast growing trees in Thailand, A. mangium and the Acacia hybrid (A. mangium x A. auriculiformis), as raw material for ethanol production through a simultaneous saccharification and fermentation process by Saccharomyces cerevisiae TISTR 5339. Alkaline pulping was applied as the pretreatment process. Optimization of ethanol production was studied using response surface methodology based on central composite design. The optimized conditions of 100 g/L solid loading and an A600 of S. cerevisiae TISTR 5339 of 2 gave observed values of ethanol production of 35.7 and 27.3 g/L, which corresponded with the predicted values of 32.32 and 26.37g/L from A. mangium and A. hybrid, respectively. This condition was then used for up-scaling in a 10-L stirred bioreactor. The improved maximum ethanol concentrations of 37.84 and 36.52 g/L were obtained from A. mangium and Acacia hybrid, respectively, within 96 h of cultivation at 30 °C and no aeration rate.

Four kinds of lignophenols (Lps) were derived from native bamboo (Sinocalamus affinis) lignin through phase separation system by using four kinds of phenols (p-cresol, catechol, resorcinol and pyrogallol) as derivatives and 72% concentrated sulfuric acid as catalyst. The resulting lignophenols were characterized by 1H-NMR, FT-IR, and GPC analysis. Then they were blended with polyhydroxybutyrate (PHB) to cast thin biocomposite films. The mechanical properties, water-absorbing qualities, and thermal properties of films were tested and discussed. The results indicated that phase separation treatment can effectively improve phenolic hydroxyl contents of lignins. The lignin macromolecule was significantly reduced to small size and well-soluble polymers. The best amounts of added Lps in composite films depended upon the kind of phenols. In present study, the mechanical properties, water-absorbing qualities, and thermal properties of biocomposite films showed good results at less than 10% Lps’ addition. This provides a possibility that a new kind of biodegradable films can be made up of engineering plastics and lignin.

A novel process was developed for the butyration of lignosulfonate (LS) with butyric anhydride in the presence of choline chloride at elevated temperatures. The degree of substitution (DS) was qualitatively and quantitatively determined byFourier transform infrared spectroscopy using the baseline method. It was found that the DS of butyrated LS products increased from 0 to the range of 0.41 to 2.14 with the addition of choline chloride, indicating that butyric anhydride-choline chloride is a novel and highly effective solvent for the butyration of LS. The DS of butyrated LS was dependent on choline chloride dosage, reaction temperature, reaction time, and the mass ratio of butyric anhydride to LS. Characterization results by proton nuclear magnetic resonance spectroscopy further demonstrated the occurrence of the butyration reaction. The results of thermogravimetric analysis showed that the thermal stability of the butyrated LS decreased with increasing degree of substitution.

This study was conducted to investigate the production of lignocellulolytic enzymes and sugars by the fungus Ganoderma lucidum during solid state fermentation (SSF) using primary sludge (PS) and wheat straw (WS) as substrates at different concentration ratios. For fungal growth on SSF, 20 g of each blended substrate was added to Erlenmeyer flasks, which were autoclaved and maintained at room temperature prior to inoculation, whereas for submerged fermentation (SF), flasks containing 25 mL of potato dextrose broth (PDB) were used as standard to check the differences between both methods of growth, and then all flasks were incubated at 25 °C in the dark, during 8 and 16 days. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis from the protein extract obtained from solid state fermentation strongly suggested that G. lucidum could produce lignocellulolytic enzymes to degrade primary sludge and wheat straw. Among the sugars, the production of xylose and mannose was disturbed by adding primary sludge. With the addition of primary sludge, high glucuronic acid content was observed. The results suggest that the combination of primary sludge and wheat straw, at concentration ratios of 1:1 to 1:3, respectively, can be used as a raw material in the production of lignocellulolytic enzymes and the bioconversion of other types of biomass by G. lucidum.

The impact on carbon dioxide (CO2) and nitrous oxide (N2O) emissions when applying hydrothermally carbonized (HTC) char to soil was investigated in a laboratory experiment with two HTC chars made from hemp (Cannabis sativa L.) dust and incubated for 131 d. Two fractions of hemp dust were collected during fiber processing (from fractionation and suction) and were carbonized at 230 °C for 6 h in water. Non-treated and water-washed HTC chars were used in incubation experiments, doubling the carbon concentration of the soil. As a result of adding HTC char to soil, CO2 emissions increased significantly in all cases compared to the control treatment. Washing the HTC chars easily removed dissolvable carbon (C) compounds, which significantly decreased CO2 emissions. Nitrous oxide emissions, following the incorporation of HTC char, did not differ from those of the control sample; however, washed HTC char treatments tended to emit less N2O than the corresponding unwashed samples. Hydrothermally carbonized char obtained from the suction of dust may play a greater role as a soil conditioner than HTC char from dust by fractionation because dust from suction accumulates to a larger degree during hemp fiber processing.

An attempt was made to generate gasoline-range aromatics from pyrolysis oil derived from rubberwood. Catalytic cracking of the pyrolysis oil was conducted using an HZSM-5 catalyst in a dual reactor. The effects of reaction temperature, catalyst weight, and nitrogen flow rate were investigated to determine the yield of organic liquid product (OLP) and the percentage of gasoline aromatics in the OLP. The results showed that the maximum OLP yield was about 13.6 wt%, which was achieved at 511 °C, a catalyst weight of 3.2 g, and an N2 flow rate of 3 mL/min. The maximum percentage of gasoline aromatics was about 27 wt%, which was obtained at 595 °C, a catalyst weight of 5 g, and an N2 flow rate of 3 mL/min. Although the yield of gasoline aromatics was low, the expected components were detected in the OLP, including benzene, toluene, ethyl benzene, and xylenes (BTEX). These findings demonstrated that green gasoline aromatics can be produced from rubberwood pyrolysis oil via zeolite cracking.

The dimensional stability of thermally modified wood exposed to several wetting-drying cycles was analyzed. Specimens of dimensions 15×15 ×15 mm were thermally modified at 180 and 200 °C. The mass loss and chemical composition of the wood were determined in order to evaluate the effect and degree of modification. Afterwards, the radial, tangential, and volumetric swelling, anti-swelling efficiency, water absorption, water repellence efficiency, and mass loss due to wetting-drying cycles were determined and compared. The specimen’s mass tended to decrease with each additional rewetting cycle. Additional extractives that were formed via thermal decomposition leached out during wetting cycles. Thermal modification positively affected the dimensional stability of all investigated species. The wood’s swelling was reduced, a result attributed to hemicellulose degradation. Dimensional stability was improved by 24 to 30% following mild treatment and by 26 to 54% following more severe treatment. When specimens were exposed to six consecutive rewetting cycles, the swelling of the modified wood increased, whereas it slightly decreased for the control (hornification). The effective dimensional stability of thermally modified wood was reduced by 34 and 28.4% for beech, 47 and 19.6% for poplar, and 19.3 and 24.5% for spruce compared to the initial anti-swelling efficiency following the first wetting cycle.

To clarify how the fire resistance of ultra-low density fiberboards (ULDFs) was improved by the Si-Al compounds and to compare the effect of fire resistance between Si-Al compounds and fire retardant (chlorinated paraffin), the fire performance of ULDFs was evaluated by cone calorimetry. Comparing Si-Al compounds to chlorinated paraffin, the heat release rate (HRR), total heat release (THR), mass loss, total smoke release, and off-gases (CO and CO2) release of ULDFs treated with Si-Al compounds significantly decreased. However, when Si-Al compounds and chlorinated paraffins were simultaneously added, the mixed fiberboards showed the best results for peak of HRR (100.76 kW m-2), time to flameout (336s), THR (21.36 MJ m-2), and residual mass (34.26%). These results indicated that the Si-Al compounds had a significant effect on improving the fire resistance of ULDFs, and the Si-Al compounds and chlorinated paraffins have a synergistic effect in ULDFs.