Research Articles

This study evaluated biological resistance of composites produced from polypropylene and either wood or bamboo by using two different levels of particle content and three different particle sizes. Composite specimens containing higher particle content and smaller particle size resulted in increased mass losses in decay resistance tests against Tyromyces palustris, a standardized test fungus, Schizophyllum commune, and Pycnoporus coccineus. As particle content increased, mass losses in laboratory termite resistance tests increased; however, decreased particle size caused slightly decreased mass losses. Higher mass losses in bamboo-composites were obtained compared to mass losses in wood-composites in biological resistance tests. There is no significant effect of particle size on water absorption and thickness swell. The IR spectrums of composite specimens showed that significant changes were seen in the wood components following the application of heat during the manufacturing process. While the IR spectrum of WPC specimens with 70% wood was similar to the wood, the composite specimen with 50% wood displayed similarities to polypropylene.

This study investigates how drying affects the quality of bamboo kraft pulps. Two bamboo pulps, cooked to different kappa numbers (i.e. 10 and 26) and D(EOP)D bleached to approximately the same brightness, were used to examine the relationship between cooking, drying, refining, and pulp/fiber properties. Drying of the two pulps caused, as expected, a loss in tensile and burst strength while the tear index was improved. The bleached high kappa pulp required less energy to reach a certain Schopper Riegler value and exhibited greater strength properties than the low kappa number pulp. These differences were also maintained after drying. Results showed that the properties of the pulp before drying determined the final strength potential of the pulp after drying. Thus, kraft cooking of bamboo to high kappa number prior to bleaching gave pulps with improved response to refining and pulp strength properties, which in turn influenced the properties of the dried pulps.

The purpose of this work was to determine the main factors influencing the phenolic content of bark during acid hydrolysis. The optimization of polysaccharides hydrolysis was done by response surface methodology. The hydrolysis was performed under atmospheric pressure in an aqueous solution of sulfuric acid. An experimental design was applied to analyze the effects of the reaction time (5 to 24 hours), acid concentration (3 to 20%), and solid/liquid ratio (1/10 to 1/5) on the weight loss, lignin content, holocellulose content, and sugar yield for the hydrolysis. The pretreated bark had a high lignin content of 60% resulting from hemicelluloses hydrolysis and phenolic compound condensation.

The objective of this study was to investigate the influence of acetylation on properties of paper made using the chemi-mechanical pulp (CMP) process. Industrial unbleached CMP pulp was provided (before and after refining), and paper handsheets were made. After drying, the specimens were acetylated on a heated cylinder at 120 °C, with acetic anhydride without catalyst. Physical and mechanical properties including water absorption, porosity, printability, brightness, D-folding, breaking length, tear resistance, and burst strength of samples were measured and compared between treated samples and the controls. The results showed that acetylation intensity was increased by increasing reaction time. Water absorption exhibited a significant reduction due to acetylation. Brightness, D-folding, and burst showed an increasing trend as a function of the degree of acetylation. Tear resistance was decreased by acetylation. The refining process improved acetylation and decreased porosity. The results indicated that most of the important factors were significantly influenced and improved by both acetylation and the refining process.

In an attempt to develop a soybean-protein wood adhesive with improved water resistance and good technical applicability, soybean protein was first degraded under strong alkali conditions and then subjected to chemical crosslinking combined with nano-modification. Results of plywood evaluation, GPC analysis, and XRD determination indicated that a soybean-protein adhesive that could bear 28 h boiling-dry cycled treatment according to standard JIS K6806-2003. The water-resistance improvement was attributed to both the chemical crosslinking of the degraded soybean protein (DSP) by MDI and the nano-modification of DSP by intercalated or exfoliated montmorillonite (MMT). Caustic degradation improved the technical applicability of the DSP adhesive by sharply reducing the viscosity of high-content protein solution. MMT nano-modification can obviously prolong the pot lives of MDI-modified DSP adhesives but slightly decrease their dry bond strength.

Extracellular xylanase and β-xylosidase production by a Penicillium janczewskii strainwere investigated in liquid cultures with xylan from oat spelts under different physical and chemical conditions. The selected conditions for optimized production of xylanase and β-xylosidase were 7 days, pH 6.5, at 30 °C and 8 days, pH 5.0, at 25 °C, respectively. The xylanase exhibited optimal activity in pH 5.0 at 50 °C and the β-xylosidase in pH 4.0 at 75 °C. The xylanase was more stable at pH 6.0 to 9.5, while the β-xylosidase remained stable at pH ranging from 1.6 to 5.5. The xylanase half-life (T50) at 40, 50, and 60 °C was 183, 15, and 3 min, respectively. β-xylosidase half-life was 144, 8, and 4 min at 50, 65, and 75 °C, respectively. When applied to the biobleaching of Eucalyptus kraft pulp, xylanase dosages of 2 and 4 U/g dried pulp reduced, respectively, kappa number by 3.0 and 3.3 units after 1 h treatment, demonstrating that the use of P. janczewskii xylanases in this process is quite promising. The pulp viscosity was not altered, confirming the absence of cellulolytic enzymes in the fungal extract.

Oxygen delignification of wheat straw soda pulp with the addition of anthraquinone (AQ) was conducted to evaluate the effects of AQ on pulp quality. The pulp yield, kappa number, intrinsic viscosity, and brightness were selected as the properties to optimize oxygen delignification. The optimal pulp was obtained via grey relational analysis with an alkali charge of 3%, oxygen pressure of 0.5 MPa at 120 °C for 85 min, and with 0.05% AQ. In contrast to conventional oxygen delignification, the addition of AQ produced pulp with a higher yield, and it did not generate other negative impacts on pulp kappa number, viscosity, and brightness. The reaction mechanism of AQ in oxygen delignification was different from that in alkali pulping.

The effectiveness of superheated steam pretreatment on the enzymatic saccharification of oil palm mesocarp fiber (OPMF) was investigated by varying the temperature (140 to 210 °C) and the retention time (20 to 90 minutes). The results showed that superheated steam pretreatment at 180 °C for 60 minutes is the optimum condition for enzymatic saccharification of OPMF. Scanning electron microscopy (SEM) images of the OPMF show that superheated steam pretreatment is able to remove silica bodies. Further characterization by FTIR and TG/DTG analysis of the raw and treated OPMF indicates that the solubilization and removal of hemicelluloses took place after the pretreatment. This suggested that superheated steam pretreatment is an effective method for the alteration of the OPMF structure and enhances the digestibility of the biomass, hence improving enzymatic saccharification.

The most prominent environmental problems facing the paper industry are those due to bleaching processes that use chlorine compounds. In this study, totally chlorine free (TCF) bleaching sequences were applied to Phyllostachys bambusoides bamboo unbleached kraft anthraquinone (AQ) pulp, using different conditions with Oxygen (O) delignification and Sodium Perborate Tetrahydrate (SPBTH) stages. The effects of oxygen pressure, SPBTH ratio, and bleaching time were studied to maximize the brightness gain at the lowest viscosity loss. Unbleached kraft-AQ bamboo pulp was applied to first stage oxygen delignification for bleaching with under 5 bar, 3% NaOH, and 12% concentration conditions. Following the chelated bleaching, Sodium Perborate Tetrahydrate (SPBTH) bleaching was carried out as the final stage. The optimum bamboo kraft pulp bleaching conditions were SPBTH level: 4%, MgSO4: 0.5%, Na2SiO3: 3%, bleaching time: 80 min., reaction temperature: 70°C, and concentration: 12%. An overall increase in the physical properties of paper was evident up to an SPBTH level of 4%. When the SPBTH level and bleaching time increased, the kappa number, viscosity, opacity, and yellowness were decreased, but the brightness was increased. Oxygen delignification with chelatation and SPBTH as a bleaching sequence was shown to be a promising alternative to produce high-quality pulp from bamboo for cleaner paper.

Considerations related to minerals and the organic composition play a major role in biomass pyrolysis, determining the distributions and properties of pyrolysate. Thus, a correlation was developed to predict the influence of both the ingredients and minerals (additive NaCl) on the yield of pyrolysates. The feedstock was processed in a tubular reactor furnace at the temperature levels for 400, 450, 500, 550, 600, 700, 800, and 900 °C using fast pyrolysis method. The obtained pyrolysates were analyzed by a gas chromatograph-mass spectrometer (GC/MS). The results indicated that the ratio of addition 1% NaCl to bamboo had the greatest impact on the ingredients of bio-oil. A higher ash content and addition of NaCl can promote more generation of CO2 and also make the char possess greater aromaticity. Therefore, de-ashing or removing minerals in the feedstock is indispensable for favorable conversion of biomass to bioenergy.