Research Articles

In order to utilize finger-jointed rubberwood as raw material for the production of structural wood products, the finger joint efficiencies of rubberwood specimens taken from three factories in Thailand were evaluated. This study investigated the finger profile, modulus of rupture (MOR), and modulus of elasticity (MOE) of finger-jointed rubberwood from all selected factories. The effect of finger orientations (vertical and horizontal) on MOR and MOE values was also examined. The results showed that all selected factories used the same finger profile for manufacturing finger jointing of rubberwood samples. The finger orientations had no noticeable effect on the MOR and MOE values. The MOR values of finger-jointed rubberwood obtained from all selected factories were different. They ranged from 55 to 78 MPa. A primary cause of failure for specimens with lower MOR values was the poor surface bonding of fingers. The MOE values of samples were similar for all selected factories ranging from 9,710 to 12,200 MPa. According to BS EN 338 (2016), finger jointed rubberwood from some factories was inappropriate for production of high strength structural wood products.

Steam explosion (STEX) is an effective method of degumming kenaf and separating kenaf fibers. The residence time has a strong effect on the STEX process, and its mechanism of degumming kenaf was studied in this paper. In this research, five different residence times were chosen to treat kenaf at 1 MPa STEX pressure. The morphological changes were recorded using an optical camera and scanning electron microscopy (SEM). The chemical and physical properties of kenaf fiber were analyzed using wet chemistry analysis and a standard mechanical test. The cellulose content increased with increasing residence time. The breaking strength of kenaf fiber reached the highest level at 5 min residence time. It was also found that four different levels of kenaf fiber exist in the steam explosion process. This finding is very helpful for the degumming method development.

Fungal glycoside hydrolase family GH12 has a single catalytic domain, exhibiting a great diversity of properties and application potentials in biomass biorefinery, feed, and textile industries. To discover new GH12 enzymes from white- and brown-rot basidiomycetes for application in the saccharification of lignocelluloses, two putative genes, VvGH12A and VvGH12B, were identified from the Volvariella volvacea genome and classified into basidiomycetous subfamily GH12-1 and GH12-2, respectively. One enzyme VvGH12A was successfully expressed in Pichia pastoris, and characterized. VvGH12A was the most active on CMC but with broad substrate specificities on polysaccharides with b-1,4 linked and b-1,3-1,4-mixed glucans. Furthermore, VvGH12A was also active on xylan and mannan. Unlike other fungal GH12 endoglucanases, VvGH12A showed a weak processivity independent of the carbohydrate-binding module (CBM) due to both “endo” and “exo” types of enzyme activity. The pH-optimum was significantly affected by the acidity and basicity of amino acid at site 98. The enzyme optimum pH was engineered to a higher neutral or alkaline pH (from pH 6.5 to pH 7.0-8.0) when Asp98 was replaced with nonpolar or neutral or amide residue. VvGH12A exhibited synergistic action with crude cellulase from Trichoderma reesei D-86271 (Rut C-30) in saccharification of delignified wheat straw, suggesting that VvGH12A plays a functional role in efficiently hydrolyzing plant cell wall polysaccharides.

The aim of this study was to evaluate the effect of corona treatment and rubber tire particle substitution proportion on the properties of particleboard. Treatments consisted of replacing 10%, 20%, and 30% Pinus oocarpa with rubber tire particles, as well as a treatment without added rubber. Rubber particles were submitted to corona treatment. Panels were produced with a nominal density of 650 kg.m−3, a 7% urea-formaldehyde adhesive, a temperature of 200 °C, a specific pressure of 3.92 MPa, and pressing time of 8 min. Panels were evaluated to determine their physical properties, including water absorption and thickness swelling after 2 h and 24 h of water immersion (TS2h and TS24h), and for mechanical properties including internal bond strength (IB), modulus of rupture (MOR), and modulus of elasticity (MOE) in static bending. Using a 30% rubber tire particle substitution proportion significantly improved the TS24h and non-return rate in thickness (NRRT) of the panels. However, rubber addition significantly decreased the mechanical properties, and only panels with up to 10% rubber met the minimum requirements of the EN 312 (2003) standard for MOR, MOE, and IB in panels for internal use (including furniture).

Carbon fiber (CF) paper is an excellent material for use in electric heating wood floors systems. In this paper, a CF paper-based electric heating wood floor was prepared using a hot pressure process. The thermal aging properties and electric heating behaviors of the CF paper-based wood floors were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and a temperature recorder. The CF paper exhibited excellent thermal stability, and its structure and morphology did not show any changes after exposure to 110 °C for 15 h. The surface temperature of the CF paper increased as input voltage increased. The positioning of CF paper in the middle of wood floors was believed to be the optimum design for electric heating wood floors. Theoretical calculations showed that the CF paper based electric heating wood floors (1.1 m2) could increase room (3 m × 4 m × 2.6 m) temperature by 12.9 °C.

Lignin removal is essential for the value-added utilization of hemicelluloses in the prehydrolysis liquor (PHL) of a kraft-based Whangee (a genus of bamboo) dissolving pulp production. In this work, a novel process concept was proposed for a calcium carbonate (CaCO3) treatment of PHL. The results revealed that the optimum dosage of an individual system of CaCO3 and polyaluminium chloride (PAC) treatment was 1.7% and 16.0%, at which the total sugars retention was 95.7% and 94.4%, the acid-soluble lignin removal 6.09% and 9.29%, and the acid-soluble lignin selectivity 58.6% and 62.4%, respectively. Alternatively, CaCO3 and 16.0% PAC were employed in a dual system to remove the lignin. Dual vs. individual system results showed that the highest total sugars retention (97.3%) and acid-soluble lignin selectivity (77.5%) occurred at the optimum dosage (2.0%/16.0%) of a dual CaCO3/PAC system, and the highest mannose (84.2%) and glucose retention (96.5%) with a dual system of 1.0%/16.0% CaCO3/PAC. Additionally, in the dual system, the adding order of 1.0% CaCO3 and then 16.0% PAC showed that 1.0%/16.0% CaCO3/PAC was more effective than 16.0%/1.0% PAC/CaCO3.

Thermal modification of wood is a chemical-free treatment that results in improved durability, enhanced dimensional stability, and a change in color throughout the entire thickness of the wood. Thermally Modified Wood (TMW) provides an opportunity for sustainable and value-added uses for timber resources that are underutilized or affected by disease or pests. TMW has commercial success in Europe, but it is in the early stages of market adoption in the United States. The main goal of this research was to identify the challenges and opportunities for TMW in the U.S. by investigating professional adopters’ perceptions of various decking materials, including thermally modified wood. In-person and online surveys were conducted for this purpose. Participants perceived that the most favorable attributes of TMW are Durability, Environmental Performance, and Aesthetics. Professional users of decking materials also considered the Cost of TMW to be relatively high, but competitive with that of tropical hardwoods and wood-plastic composites. A block of conjoint analysis questions helped to uncover the target audience’s priorities and tradeoffs that they are willing to make between the different product attributes. Results from this research are useful to inform the formulation of effective marketing strategies.

The chemical modification of bamboo culm was explored based on in situ construction of polyhydroxyethyl methylacrylate (PHEMA) and polymethyl methylacrylate (PMMA) networks into the cell walls. Scanning electron microscopy revealed that the synthesized polymers distributed in both the cell walls and the lumen with the pits blocked. The dimensional stability was tested under three water soaking-drying and moistening-drying cycles. The swelling efficiency of the treated bamboo was under 8% in three cycles of water soaking and drying cycles and was 4% in moistening-drying cycles. The anti-swelling efficiency was 60.5%, 52.7%, and 46.3%, respectively, in the moistening-drying cycles. Laboratory tests on mold resistance showed that no mycelium formed on the treated bamboo, while the untreated control was 100% covered by mold fungi.

Bark as a biowaste has a huge availability throughout the world and has had limited use in industrial applications. Black pine bark and oak bark were considered in this work. The aim was to manufacture a new biocomposite with different combination of black pine bark, oak bark, polypropylene, polyethylene, and a coupling agent, and to determine some physical and mechanical properties of the manufactured biocomposites. Density, thickness swelling, water absorption, tension strength, modulus of rapture and modulus of elasticity in bending and tension of the biocomposites were determined. According to the results, thickness swelling and water absorption properties were improved up to 80% when compared with wood-plastic composites (WPC) produced with wood flour. Although the new biocomposites displayed lower mechanical performance in comparison of biocomposites made with wood flour, the observed results were satisfactory. Based on the results of this study, black pine bark and oak bark can be used as filler materials in WPCs production. Hereby, these bark materials can be the raw material for value-added products. Bark use in biocomposite production also can contribute to reduced requirements of wood material and petroleum products.

The dissolution rates of the chemical compositions of alcohol-benzene extractables (ABE), holocellulose, hemicellulose, and lignin in wheat straw (WS) under different pretreatment conditions were investigated. The individual and interactive effects of three independent parameters, namely, sodium hydroxide (NaOH) dosage (x1: 8 wt.% to 12 wt.%), sodium sulfide (Na2S) dosage (x2: 10 wt.% to 18 wt.%), and time to maximum temperature (x3: 100 min to 140 min) on screened yield, Kappa number, and brightness of wheat straw pulp (WSP) were analyzed via response surface methodology (RSM). The results suggested that the quadratic equations were in good agreement with the experimental figures in the present work. The relative errors of verification results were less than 5%, which indicated that the selected model for explaining the relationship between the variables and the responses was correct. In addition, the relationships between the screened yield, reject yield, brightness, and Kappa number were described and explained. Wheat straw pulpability was optimized in this study via RSM.