Wood and Fiber Science (E-Journal)
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Resistance of Flat-Pressed Wood-Plastic Composites to Fungal Decay: Effects of Wood Flour Content, Density, and Manufacturing Technology
Get PDFUse of wood-based materials in exterior application is inherently at risk of degradation caused by fungal decay. This risk also holds for wood-plastic composites (WPCs), whether they are extruded into rod-shaped elements or flat-pressed to large-dimensioned panels. In this study, to show the potential of WPC panels in exterior applications, fungal decay was studied by investigating mass loss in an agar-block test using Gloeophyllum trabeum (Gt), Coniophora puteana (Cp), and Pleurotus ostreatus (Po) as test fungi. Characterization of WPC panel durability was performed in comparison with solid wood samples by calculating the decay susceptibility index (DSI). Moreover, durability of WPC panels from laboratory (single-daylight press) and industrial (continuous double-belt press) manufacturing were compared with commercial extruded WPC decking planks. Experiments showed that the wood particles in flat-pressed panels were well protected against fungal decay by the polymeric matrix. The fungal-induced mass loss depended on panel density and wood flour content. Using DSI as an evaluation tool, WPC panels were found to be more durable than wood samples used as reference materials (DSI < 100)
Strength Loss and Hazard Assessment of Euphrates Poplar Using Stress Wave Tomography
Get PDFStress wave tomography is a noninvasive testing method for diagnosing defects in standing or cut trees. For this study, the technique was used to diagnose defects on 15 disks of Euphrates poplar (Poulus euphratica Oliv.) cross-sections. Two-dimensional tomograms were generated and used to estimate strength loss and assess potential tree stem failures. Results found that stress wave tomograms can effectively locate decay and void dimensions and that there was a logarithmic significant relationship (r = 0.9679) between real tomographic defect areas and visual defect areas indicated by the tomograms. This regression relationship could improve accuracy of hazard assessment in historic trees when using stress wave tomography. Strength loss was calculated based on Wagener, Coder, and Mattheck's equations. These three equations can provide effective internal tree stem weakness assessment. However, strength loss between tomographic defect areas in cross-sections and real visual defect area had a significant 0.05 statistical difference. The results of this study provided insight into defect diagnosis and hazard assessment for trees in China, especially those with historical significance
Economics of Merchandising Pulpwood in West Virginia
Get PDFThere has been renewed interest in determining the feasibility of pulpwood merchandising yards in the Appalachian region. Intensive merchandising is a potential way to supply raw material to traditional markets as well as current and new weight-based pulp markets at a lower cost. The feasibility of developing a hardwood pulpwood sorting merchandising yard in West Virginia was investigated. More than 171,000 kg of pulpwood was procured for this project. The majority of the pulpwood purchased was red and white oak followed by black cherry and hickory. Results indicated that between 3.6 and 6.0 t of pulpwood was needed to saw 1 m3 of lumber. The merchandising operation resulted in negative net revenues for all species studied. Handling cost was found to be one of the most important issues leading to this finding. However, it was found that merchandising low-quality sawlogs on the log-landing could be profitable. The cost and revenues reported in this study represent a complex blend of pricing and product yields that are dynamic with time. As weight-based markets, such as engineered products and bioenergy, expand and competition increases with traditional markets, inputs could be refined which would create a new set of merchandising options for roundwood
Effect of Pile Yarn Type on Absorbency, Stiffness, and Abrasion Resistance Of Bamboo/Cotton and Cotton Terry Towels
Get PDFThis study compared absorbency, stiffness, and abrasion resistance characteristics of bamboo/cotton and cotton terry towels. Bamboo/cotton terry towels were woven with bamboo pile yarn, which has been commonly used in textiles in recent years, whereas cotton terry towels were woven with cotton pile yarns. Desized woven terry towels without dye or any further finishing treatments were produced under industrial conditions. Effects of pile yarn type and pile height on physical and mechanical properties of fabrics were compared using analysis of variance. Design Expert 6.01 (Stat-Ease, Inc., Minneapolis, MN) was used for statistical analyses. It was found that abrasion of towels with bamboo pile yarn was higher than that of towels with cotton pile yarn at high abrasion cycles, whereas stiffness of bamboo/cotton towels was lower than that of cotton towels. Also, it was found that sinking time of terry towels with cotton pile yarn was longer than that of towels with bamboo pile yarn
Process-Related Mechanical Degradation of the Wood Component in High-Wood-Content Wood-Plastic Composites
Get PDFMicromorphological studies of wood-plastic composites (WPC) are crucial for deeper understanding of their physical, mechanical, and durability properties. The objective of this study was to examine process-related mechanical degradation of the wood component in an extruded high-wood-content WPC. WPC with ≈70% wood content and three distinctly different ground wood components were manufactured by a conical extrusion technology, ie WPC were prepared with an unmodified, acetylated, or thermally modified wood component. Size and shape of wood components were determined before and after the extrusion process. Micromorphology of WPC samples was studied using a scanning electron microscope (SEM) and a surface preparation technique based on UV laser ablation. This micromachining technique was also applied to prepare thin specimens for micromechanical analysis using a tensile stage mounted in a SEM. Results show that extrusion processes cause a significant mechanical degradation of the wood component. Degradation was most pronounced for the thermally modified wood component, and interestingly, this resulted in a more homogenous WPC micromorphology compared with WPC with unmodified and acetylated wood components. WPC with thermally modified wood also exhibited the highest micromechanical strength
Plant Age Effect on Mechanical Properties of Moso Bamboo (Phyllostachys Heterocycla Var. Pubescens) Single Fibers
Get PDFBamboo fiber has greater mechanical strength than certain other natural fibers and could therefore be a candidate for production of fiber-reinforced composites. Single fibers were isolated from Moso bamboo samples taken from plants between 0.5 and 8.5 yr old. Mechanical properties of single fibers (tensile strength, modulus of elasticity (MOE), and other mechanical related properties such as the microfibril angle and fiber cross-sectional area) were studied. There was no significant variation with age in average MOE and fracture strain of the bamboo fibers. Results indicate that the thickening growth of cell walls in bamboo fibers near the outer surface of bamboo is almost complete by 0.5 yr. Therefore, fibers from 0.5 to 8.5 yr old plants may be used for making fiber-reinforced composites
Pretreated Central Appalachian Hardwood Residues and their Potential for Bioenergy Production
Get PDFHardwood residues of yellow-poplar (Liriodendron tulipifera) and northern red oak (Querus rubra) were pretreated with two alkaline solutions: 1) ammonium hydroxide and sodium hydroxide (ASO) and 2) hydrogen peroxide/ammonium hydroxide and sodium hydroxide (PASO) mixtures. After pretreatment, particulates of yellow-poplar, northern red oak, and pulp were enzymatically hydrolyzed with cellulases (Accellerase 1000 [Genencor International, Rochester, NY]) for comparisons of glucose production. ASO pretreatment increased the lignin solubility of yellow-poplar and northern red oak by an average of 8.6%. PASO pretreatment performed better than ASO pretreatment with respect to lignin decrease in the pretreated wood. Sugar yield after enzymatic hydrolysis ranged from 70-81 mg/mL for PASO-pretreated yellow-poplar and northern red oak residues, respectively, and 50-62 mg/mL for ASO-pretreated yellow-poplar and northern red oak
Characterizing Wood Liquefaction by Fractal Geometry Approach
Get PDFThis study characterized wood liquefaction by the fractal geometry method. Chinese fir (Cunninghamia lanceolata Hook.) fine powderwas liquefied under various conditions of phenol-to-wood ratio (3:1, 4:1, and 5:1), catalyst content (4, 6, and 8%), and temperature (130, 150, and 170°C). The surface fractal dimension of liquefiedwood residueswas determined at different liquefaction time levels (30, 60, 90, 120, 150, and 180min) by software based on the cubic coveringmethod. The relationship between fractal dimension and residue content was examined quantitatively. Results indicated that 1) surface fractal dimensions of liquefied wood residues were between 2.27 and 2.30 under all liquefaction conditions; 2) surface fractal dimension was inversely related to liquefaction time, and it decreased faster at early liquefaction stages; 3) surface fractal dimension was inversely related to phenol-to-wood ratio, catalyst content, and liquefaction temperature; and 4) the relationship between surface fractal dimension and residue content could be described by a linear function with high R2 values. This study provides a new alternative to the arsenal of wood liquefaction characterization methods and also sheds light on some fundamental aspects of wood liquefaction research
Technical Note: Solid Wood Properties of Eucalyptus Camaldulensis Planted for Pulpwood Production in Thailand
Get PDFSolid wood properties of two Eucalyptus camaldulensis clones (clone A and clone B), derived from different pulp and paper companies and planted in Thailand for pulpwood production, were investigated to evaluate the possibility for lumber production. Clone A had significantly higher Young's modulus, greater density, and straighter grain compared with clone B. These results suggest that some clones may have more favorable properties for lumber production than others. Thus, wood properties should be included in clonal trials and early testing of this species