Volume 10 Issue 2

In a previous study by the authors, particleboard was manufactured using a new natural adhesive composed of tannin and sucrose. The optimal ratio between tannin and sucrose was 25/75, and the suitable resin content was 30 to 40 wt%. In this study, the effects of hot pressing temperature and hot pressing time on board properties were investigated. The optimal values for the hot pressing temperature and hot pressing time were found to be 220 °C and 10 min, respectively. When the particleboard was made under these optimum conditions, the physical properties of the particleboard bonded with tannin and sucrose met the requirement of the JIS A 5908 type 18 standard (2003). Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), insoluble matter, and Fourier transform infrared spectroscopy (FT-IR) tests were carried out. The results of TGA and DSC measurements showed that the weight loss and endothermic reaction of the adhesive composed of tannin and sucrose at a ratio of 25/75 occurred at 204 and 215 °C, respectively. When the adhesive was heated at 220 °C for longer than 10 min, the level of insoluble matter was higher than 70 wt%. FT-IR analysis showed the existence of a furan ring, a carbonyl group, and dimethylene ether bridges in the cured adhesives before and after the boiling treatment. When the heating time was longer than 10 min, no further change of chemical structure was observed.

Comparison of industrial and laboratory pulps from Pinus radiata showed higher energy requirement and lower tear index at the same tensile strength in the case of industrial pulps. Chemical differences between pulps were negligible and cannot explain the strength differences observed. Morphology of the fibers changed during processing with an increase in kinks and curls for industrial pulps. Increased twists and wrinkling in mill fibers were observed based on scanning electron microscopy images. Results from water retention value and fiber saturation point measurements showed reduced water holding ability of industrial fibers. Simons’ stain and hydrogen nuclear magnetic resonance confirmed a higher proportion of macropores in the fibers of industrial compared to laboratory pulps. Evidence supports the presence of both micropore closure and creation of new mesopores and macropores during industrial processing. A combination of fiber damages, porosity changes, and induced deformations seems to play the main role in the lower strength properties of industrial pulps when compared to laboratory pulps.

Increased interest in oils and silicones as hydrophobic agents creates the need for testing, with the aim of better understanding their field performance and preparation for an eventual market entrance of these products. This study reveals the aboveground test performance of wood impregnated with epoxidised linseed oil (ELO) and organofunctional alkoxysilanes and compares the achieved results with the significantly more severe inground exposure and initial laboratory tests. Since ELO and siloxanes are not active ingredients, they were combined with fungicides for better performance. Various oil and alkoxysilane retentions and combinations with boric acid, organic fungicides, and creosote were impregnated in wood and tested. Untreated, chromium-copper-arsenate (CCA)-treated and thermally modified samples served as references. Long-term aboveground and inground testing of the studied formulations enforced the conclusion that ELO combined with biocides is suitable protective formulation for timber in both above- and in-ground exposure. Two alkoxysilanes were more effective in timber exposed aboveground. No decay was registered in the ELO and alkoxysilane treated lap-joint samples, while the untreated controls were close to failure after five years of exposure.

The glycoside hydrolase family 43 from Paenibacillus curdlanolyticus strain B-6 (GH43B6) exhibited multifunctional properties, including exo-β-xylosidase, endo-xylanase, and α-L-arabinofuranosidase enzymatic activities. GH43B6 released xylose as a hydrolysis product from the successive reduction of xylooligosaccharides as a result of exo-β-xylosidase activity. Moreover, GH43B6 also predominantly released xylose from low-substituted xylan derived from birchwood. However, when the highly substituted rye flour arabinoxylan was used as a substrate, exo-β-xylosidase activity changed to endo-xylanase activity, indicating that the enzymatic property of GH43B6 is influenced by the substituted side groups of xylan. For α-L-arabinofuranosidase, arabinose was released from short-chain substrates including p-nitrophenyl-α-L-arabinofuranoside and α-L-Araf-(1→2)-[α-L-Araf-(1→3)]-β-D-Xylp. This study reports the novel trifunctional properties of GH43B6 containing exo- and endo-activity together with xylanolytic debranching enzymatic activity, which increases its potential for application in lignocellulose-based biorefineries.

Studying the stereochemistry of lignin as a natural chiral polymer may have scientific and technical importance regarding the behavior of lignin and delignification processes. In the present study, the hydroxyl groups of α-carbon (chiral center) in phenyl propane structural units of lignins and two model compounds were selenated. Then, the 77Se nuclear magnetic resonance (NMR) spectra of the selenated samples were examined in order to determine the ratio of diastereomers (erythro and threo). The results revealed that lignins are a mixture of different ratios of two diastereomers. This finding may have scientific importance and practical impacts on the chemistry of delignification processes and other related phenomena in the domain of pulp and paper sciences.

In this paper, the efficiency and mechanisms of two pectinases (pectate lyase (PL) and alkaline pectinase (AL)) to hydrolyze model pectic substances and dissolved and colloidal substances (DCS) of Masson pine bleached chemithermomechanical pulp (BCTMP) were investigated. The cationic demand values of model polygalacturonic acid and DCS could be reduced to about 20% and 60 to 70% by these two pectinases, respectively. However, due to the unmethylated form of the pectic substances in DCS of BCTMP, PL is more efficient than AL. The hydrolysis mechanism of polygalacturonic acid with PL was investigated. The results showed that there was no need to hydrolyze the polymeric pectic substance to their monomers, since a minimum average degree of polymerization (DP) of 6.0 was required for pectic acid to interact strongly with cationic polymers and reduce the efficiency of the latter.

Enhancement of oxygen delignification is critical to improve subsequent bleaching efficiency while being environmentally compatible. In the present study, xylanase was used to improve the delignification process of poplar kraft pulp. Results showed that the kappa number reduction ratio (KRR) of 14.5% was achieved for the pulp under xylanase-assisted oxygen delignification processes when compared to the control without xylanase treatment. Other pulp properties, such as intrinsic viscosity and brightness, also improved somewhat; i.e., viscosity increased by 28 mL/g units and ISO brightness increased 1.4% points. Furthermore, 31P-NMR was employed to characterize the chemical structure of the residual lignin of the pulps before and after oxygen delignification. It showed that the condensed phenolic and syringyl hydroxyl groups decreased significantly for the xylanase-assisted oxygen-delignified pulps.

Rubber has been shown to be one of the most important plantation crops in Malaysia, and rubber tree biomass has widespread applications in almost all sectors of the wood products manufacturing sector. Despite its abundance, the exploitation of rubberwood biomass for energy generation is limited when compared to other available biomass such as oil palm, rice husk, cocoa, sugarcane, coconut, and other wood residues. Furthermore, the use of biomass for energy generation is still in its early stages in Malaysia, a nation still highly dependent on fossil fuels for energy production. The constraints for large scale biomass energy production in Malaysia are the lack of financing for such projects, the need for large investments, and the limited research and development activities in the sector of efficient biomass energy production. The relatively low cost of energy in Malaysia, through the provision of subsidy, also restricts the potential utilization of biomass for energy production. In order to fully realize the potential of biomass energy in Malaysia, the environmental cost must be factored into the cost of energy production.

Torque rheological properties of wood flour/chitosan/PVC (WF/CS/PVC) compounds were measured by a torque rheometer using roller-style rotating blades at various setting temperatures (175 and 185 °C) and rotation speeds (30, 45, 60, and 75 rpm). The torque rheological parameters were calculated based on the Marquez model and Arrhenius equation. The torque rheological curves of WF/CS/PVC composites were similar to WF/PVC composites without chitosan. The classical Marquez model was verified to be suitable for both WF/PVC and WF/CS/PVC composites. Specifically, the activation energy (ΔE), n value, and range of C(n)m for the former and latter were 27.698 kJ·mol-1 and 29.237 kJ·mol-1, 0.382 and 0.381, and 4.415 to 5.749 N·m·sn and 4.652 to 6.079 N·m·sn, respectively. The rheological properties of WF/CS/PVC composites did not show a great qualitative enhancement compared to WF/PVC composites.

The technical feasibility of using calcium oxide (CaO) as a sorbent for CO2 and Fe-Cr as a catalyst for the water-gas shift (WGS) reaction using syngas for the steam gasification of biomass was investigated. The effects of temperature, steam to biomass mass ratio, CaO to biomass molar ratio, and Fe-Cr WGS catalyst on gas composition were studied. Within a temperature range of 250 °C to 550 °C, the H2 concentration increased from 1.2% to 17.1%, with a total increase of 16%. As the steam rate increased within the range of 0 kg/h to 0.12 kg/h, the maximum value of H2 concentration increased from 12.1% to 17.13%, with a total increase of 5%. As the CaO to biomass molar ratio was increased from 0 to 2, the CO2 concentration demonstrated a minimum value of 1.3%, and the H2 concentration exhibited a maximum value of 53.1%. A catalyst to biomass mass ratio of 1 resulted in the minimum value of CO2 concentration, which decreased from 7.9%, in the absence of CaO, to 1.6%. A CaO to biomass molar ratio of 1.5 resulted in the maximum value of H2 concentration, which increased from 27.6%, in the absence of CaO, to 63%.