Wood and Fiber Science (E-Journal)
Not a member yet
2592 research outputs found
Sort by
Within-Stem Variation in Wood Properties of Red Pine (Pinus Resinosa AIT.)
Get PDFSome physical and mechanical properties, including tension parallel-to-grain, tension perpendicular-to-grain, and shear parallel-to-grain, and their variations within the tree stem of red pine (Pinus resinosa Ait.) were evaluated in this study. All these wood properties were obtained based on small clear specimens. Results indicate that wood properties tended to increase from pith to bark in the radial direction and decrease from bottom to top in the longitudinal direction. These variations in wood properties can be mainly attributed to the differences in wood characteristics of juvenile and mature wood. The influence of growth ring orientation was not statistically significant on shear strength parallel-to-grain and tensile strength perpendicular-to-grain. Information on variation in mechanical properties of wood across a tree stem is essential to investigate the influence of sawing pattern on mechanical properties of lumber products
Analysis of Cutting Forces in Straight-Knife Peripheral Cutting of Wood
Get PDFEffects of rake angle, wavelength, and depth of cut on cutting forces during straight-knife peripheral milling of sugar maple were determined. Progressions of normal (FN) and parallel (FP) force components during a typical up-milling cycle were determined. Results showed that at the initial step of the cut, FN was negative, ie the knife edge pushed the workpiece downward. The part of the knife path that remained visible on the machined surface was always created in such a situation. As the knife edge advanced in the cutting path, FN increased, reached a maximum negative value, then decreased to 0 N/mm, turned positive, and continued upward. FP was always positive and increased as chip thickness increased. Positive FN and FP reached a maximum just prior to emergence of the knife from the workpiece at about the maximum thickness position. However, when chip splitting occurred, the maximum positive FN and FP occurred before that maximum thickness position was reached. Maximum negative FN and FP increased as rake angle decreased and as wavelength increased. Maximum positive FN increased as rake angle and wavelength increased. Maximum positive FN and FP were also affected by depth of cut but to a lesser degree. Impact of these maximum cutting forces on production of defects was analyzed, and ways to decrease them were discussed
Influence of Hemicellulose Extraction on Water Uptake Behavior of Wood Strands
Get PDFHemicellulose is the most hydrophilic and unstable of wood polymers. This study examined the effect of decreasing the amount of hemicellulose in wood on wettability and water uptake behavior of wood strands. Two methods were used for decreasing hemicellulose in wood strands: hot-water extraction and enzyme treatment. Contact angle measurements showed a decrease in wettability of wood strands after hot-water extraction of hemicellulose. These results indicated a decrease in hydrophilic character of wood strands. Amount of water taken up by strands treated with hot-water extraction decreased as percentage of mass loss increased. The enzyme-pretreated wood strands also absorbed water at lower rates compared with untreated samples. Results indicated that hemicellulose has a great influence on water absorption of wood and that decreasing hygroscopocity of wood by extraction of hemicelluloses is possible
Review of United States and International Formaldehyde Emission Regulations for Interior Wood Composite Panels
Get PDFThis article compares and contrasts formaldehyde emission regulations for interior wood composite panels in the US, the European Union, Japan, and China. Historical context, product-specific emission limits, test methods, and product certification requirements are detailed for each emission standard. In particular, the recently enacted California Air Resources Board (CARB) formaldehyde regulation is compared with established international formaldehyde regulations and differences in four key areas, emission limits, documentation, deconstructive testing, and enforcement, are highlighted. Implications of CARB and US Environmental Protection Agency regulatory actions are discussed, and future work is suggested in the rapidly evolving and highly debated arena of formaldehyde emission policy
Stress Relaxation of Wood Flour/Polypropylene Composites at Room Temperature
Get PDFTo investigate the time-dependent property of wood flour/polypropylene (PP) composites and the effect of coupling agents on it, both tensile stress relaxation and compressive stress relaxation curves were determined at various wood contents (0, 20, 30, 40, 50, 60, and 70%) without a coupling agent and were also determined at 50 and 60% wood contents with different coupling agents such as maleic anhydride grafted polypropylene (MAPP) and silane. Bending modulus of rupture (MOR) and modulus of elasticity (MOE) of wood flour/PP composites at various wood contents without coupling agents and at 60% wood content with MAPP and silane as coupling agents were also tested to compare with stress relaxation results. All measurements were performed at 26 ± 1°C. Results showed that 1) the tensile stress relaxation appeared to have similar trends with compressive stress relaxation (They both declined obviously after adding coupling agents at the same wood content.); 2) wood content had a great influence on stress relaxation behavior of wood flour/PP composites (The lowest stress relaxation rates appeared at 40% wood content for both tensile and compressive stress relaxation of wood flour/PP composites without coupling agent, suggesting the best compatibility between wood and PP is at about 40% within the experimental conditions of this study.); 3) optimal loading level of a coupling agent for stress relaxation varied with type of coupling agents and wood content (Within the experimental conditions used in this study, the optimal loading level for MAPP was 2% at both wood contents, whereas for silane, it was 1.5% at 50% wood content and 2% at 60% wood content.); and 4) lower stress relaxation rates corresponded to higher bending MOR and MOE values at 60% wood content. This suggests that long-term performance of wood flour/PP composites would be consistent with bending strength at room temperature
Laboratory Evaluation of Borate: Amine: Copper Derivatives in Wood for Fungal Decay Protection
Get PDFThis study aimed to evaluate borate:amine:copper derivatives in wood for fungal decay protection as well as the permanence of copper and boron in wood. Each of four derivatives of borate: amine:copper prevented fungal decay in wood. Disodium tetraborate decahydrate (borax):amine:copper derivatives with 0.61-0.63% retention after water leaching prevented decay by Gloeophyllum trabeum (Gt) and with 0.64% retention prevented decay by Trametes versicolor (Tv). Leaching did not decrease decay resistance for either Gt or Tv. Disodium octaborate tetrahydrate (DOT):amine:copper derivatives with 1.14-2.93% retention after water leaching prevented decay by Gt and with 0.54-1.19% retention prevented decay by Tv. Leaching decreased decay resistance to Gt but not to Tv. Higher copper and boron in disodium borax:amine:copper derivatives contributed to more decay resistance to Gt and Tv than that of DOT:amine:copper derivatives as evidenced by elemental analysis. IR spectra of wood treated with 5% borate:amine:copper derivatives after water leaching showed increased absorption at 1632-1635 cm-1 compared with the control. This increased absorption was partly attributable to carbonyl of copper carboxylates from oxidation of hemiacetals of hemicelluloses and cellulose by copper (II) ions and carbonyls of copper (II) quinone methides by oxidation of guaicyls by copper (II) ions. It was also partly attributable to carbonyls of copper carboxylates from hemicelluloses and phenolates from lignin through ion exchange reactions. These oxidation and ion exchange reactions of copper with wood components may account for their efficacy and long-term performance
Morphological Characteristics of Cellulose Nanofibril-Filled Polypropylene Composites
Get PDFNano-sized cellulose fillers (cellulose nanofiber [CNF] and microfibrillated cellulose [MFC]) and a micron-sized cellulose filler (microcrystalline cellulose [MCC]) were used as fillers in polypropylene (PP) composites. Cellulose-filled PP composite samples were manufactured and tested, and their morphological properties were examined to describe morphological characteristics of fracture surfaces at different filler loading levels after mechanical testing. Scanning electron microscopy analysis showed polymer stretching as the major component causing plastic deformation in fracture surfaces of CNF- and MCC-filled composites, whereas analysis of MFC-filled composites exhibited brittle deformation. Individual CNF and MFC fibers were separated and dispersed in the matrix polymer, although considerable agglomeration was observed beyond 6% (wt) filler loading, which resulted in sustained tensile and flexural strength. Mechanical property test results showed that in the case of CNF and MFC, composites sustained considerable tensile and flexural strength up to 10% (wt) filler loading, whereas tensile and flexural strength of MCC-filled composites decreased continuously
Technical Note: Velocity of Ultrasonic Waves in Live Trees and in Freshly-Felled Logs
Get PDFThe objective of this study was to evaluate variations between the velocity of ultrasonic wave propagation in trees and in freshly felled logs as well as to investigate the correlation between those speeds and corrections that would improve this correlation. The study was conducted using 210 exotic trees growing in Brazil, including the species Eucalyptus grandis, Pinus elliottii, Toona ciliata, and Eucalyptus resulting from cloning. Although the velocity of ultrasonic wave propagation in a tree (Vt) is not equal to that in a freshly felled log (Vt), the two values are correlated such that Vt can be obtained from Vst. The regression indicated a nonlinear equation for determining the log velocity from the tree velocity
Life Cycle Inventory of Manufacturing Prefinished Engineered Wood Flooring in Eastern us with Comparsion to Solid Strip Wood Flooring
Get PDFBuilding products have come under increased scrutiny because of environmental impacts from their manufacture. Our study followed the life cycle inventory approach for prefinished engineered wood flooring in the eastern US and compared the results with those of solid strip wood flooring. Our study surveyed five engineered wood flooring manufacturers in the eastern US. These production facilities represented 18.7% of total annual production in 2007. Primary data collected for 2007 included annual production, energy consumption and type, material inputs, emission data, product outputs, and other coproducts. Modeling data estimated biogenic and fossil CO2 emissions at 623 and 1050 kg/m3, respectively, and volatile organic compounds at 1.04 kg/m3. Cumulative allocated energy consumption for prefinished engineered wood flooring was 23.0 GJ/m3 with 40% coming from coal. Unfinished solid strip flooring cumulative energy consumption was only 6.50 GJ/m3 with 65% from biomass, roughly half that of unfinished engineered wood flooring. However, after converting to an area (in-use) basis, unfinished engineered wood flooring consumed 136 MJ/m2 compared with 123 MJ/m2 for unfinished solid strip flooring. After changing to an in-use parameter, the two wood flooring products were similar in energy consumption during manufacturing, but engineered wood flooring still consumed significantly more fossil fuel