Wood and Fiber Science (E-Journal)
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THEORETICAL ESTIMATION OF MECHANICAL PROPERTIES OF PLYWOOD-SHEATHED SHEAR WALL WITH COMBINED USE OF ADHESIVE TAPE AND WOOD DOWELS
Get PDFShear walls often function as elements that provide resistance to horizontal external forces exerted on wooden frames. Many shear walls with superior strength performance have been developed for this purpose. Amidst this backdrop, we have attempted to develop a shear wall that, in addition to strength performance, decreases the time and labor required for disposal. More specifically, the authors proposed a novel “metalless” shear wall: a shear wall in which industrial double-sided adhesive tape is used to attach plywood to the framework. Also, wood dowels are used as supplementary connectors with the aim of enhancing strength performance. Unlike conventional shear walls that use nails and metal fixtures, separation at the time of disposal is unnecessary, and therefore, disposal time and labor of the wall are anticipated to be significantly decreased. Thus, this study involved demonstrating and verifying a methodof theoretical analysis for the mechanical performance of these kinds of shear walls toward in-plane shear force. Specifically, this study derived a method to estimate the mechanical behavior (load-deformation angle relationship) of plywood-sheathed shear walls based on shear performance obtained from double shear tests of joint specimens with the combined use of adhesive tape and wood dowels. Also, the validity of the method was experimentally verified. The results showed that the method proposed in this study was able to estimate the mechanical behavior and mechanical properties of the newly proposed shear wall, and the validity of the method was confirmed
THERMOGRAVIMETRIC ANALYSIS OF THERMAL AND KINETIC BEHAVIOR OF ACACIA MANGIUM WOOD
Get PDFThermogravimetric analysis was used to study the thermal behavior of Acacia mangium wood under inert atmosphere at heating rates ranging from 5 to 15C min -1, from room temperature to 800C. Weight losses of A. mangium wood in inert atmosphere were found to occur in three stages. These three states are generally associated with the decomposition of the three main components of the lignocellulosic materials. Most decomposition occurred in the range of 300-400C (80% weight approximately). The kinetic parameters of the process were evaluated using the independent parallel reaction model, attributed to the three main components of lignocellulosic materials: hemicelluloses, cellulose, and lignin. The values of activation energy, preexponential factor, and contribution factor were similar to those reported in other studies for this type of biomass. The model proposed predicted an acceptable correlation between the experimental and the calculated curve to the decomposition of A. mangium, with an error of less than 3% of deviation in the temperature range studied
WITHDRAWAL AND COMPRESSION FORCE CAPACITY OF PINNED END-TO-END ROUND MORTISE-AND-TENON WOODEN JOINTS
Get PDFTests were conducted to determine the withdrawal and compression force capacity of endto-end round mortise-and-tenon joints constructed of nominal 88.9- by 88.9-mm Hem-Fir studs with tenons cross pinned with either one or two pins. For specimens with one tenon cross pin, withdrawal force capacities increased from 9.1 to 14.4 kN as tenon diameters increased from 31.8 to 50.8 mm. Comparable values for joints constructed with two (smaller) cross pins ranged from 15 to 21.9 kN. Capacities of comparable joints with a single 12.7-mm tenon cross pin loaded in compression decreased from 220 to 165.7 kN as tenon diameters increased from 31.8 to 50.8 mm. In the case of compression specimens, cross mortises cut through the follower member of the joint substantially decreased compression force capacity from 172.8 to 113.2 kN as tenon and cross-mortise diameters increased from 31.8 to 50.8 mm. Compression force capacities for comparable specimens with 19.1-mm cross mortises in the follower members ranged from 157.5 to 122.3 kN for tenon diameters ranging from 31.8 to 50.8 mm
THE INFLUENCE OF NANOCELLULOSE AND SILICON DIOXIDE ON THE MECHANICAL PROPERTIES OF THE CELL WALL WITH RELATION TO THE BOND INTERFACE BETWEEN WOOD AND UREA-FORMALDEHYDE RESIN
Get PDFUrea-formaldehyde (UF) resin is used as an adhesive in the most wood-based composite plants in China. The quality of such composites is strongly affected by the mechanical properties of the cell wall in relation to the interface between UF resin and wood. This research investigates the mechanical properties of the cell wall in the bond interface of wood and UF resin with nanocellulose and silicon dioxide, and compares the mechanical properties of wood-adhesive interface cell walls to their gluing strength. The hardness and reduced modulus of the cell wall were investigated by means of nanoindentation. The test results show that there was a close relationship between the mechanical properties of the cell walls at the wood-adhesive interface and the percentage of nanocellulose or SiO2 in the UF. The shear strength of UF resin with nanofibrillated cellulose (NFC) or nano-SiO2 in bonded wood also gradually increased when the content of these two kinds of nanomaterials was increased from 0% to 2%
EQUILIBRIUM MOISTURE CONTENT UNDER VACUUM CONDITIONS
Get PDFThe equilibrium moisture content (EMC) of three species was measured under vacuum conditions. Temperature, RH, and ambient pressure in a chamber were controlled during the experiments to obtain accurate EMC measurement under vacuum. Based on the experimental results and on the Hailwood–Horrobin model for EMC, the desorption isotherms of wood under vacuum were analyzed.EMC charts and a database under vacuum conditions were also built. Results showed that the desorption isotherms of wood under vacuum conditions also presented a typical sigmoid shape similar to the one at atmospheric conditions. The effect of ambient pressure on EMC was small at high RH ranges and became obvious with decreasing RH. Also, the EMC of ambient pressure from 53.3 to 101.3 kPa was not obvious because the difference in EMC was only 0.1-0.4%. Conversely, the effect of pressure became greater from 53.3 to 13.3 kPa and the difference in EMC was 1.2-1.9%. EMC corresponding to temperature, RH, and ambient pressure at vacuum conditions was built with the chart and equations based on experimental results from the real-time MC measurement for vacuum drying and serves as an aid in wood research and drying control under vacuum conditions
ANALYSIS OF CERTIFIED WOOD PRODUCT USE IN COMMERCIAL LEED GREEN BUILDING PROJECTS
Get PDFThere is a growing demand for green building products within the United States. Because of this increased demand and interest in green products, the potential exists for wood product manufacturers to gain additional market share opportunities within the green building sector. The overall objective of this study was to use spatial analysis techniques to evaluate the growth of green building projects and the use of certified wood products (CWPs) within these projects. The focus of this study was on green building projects certified as part of the US Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED) that obtained the certified wood credit. Using spatial analysis techniques, this study was able to identify geographic areas in which wood products were used and awarded points toward green building certification. Results indicated a trend of commercial LEED-certified projects that obtained the certified wood credit being geographically concentrated with time. The study also identified various “hot spot” county clusters throughout the United States for commercial LEED-certified projects that obtained certified wood materials. A spatial econometric regression analysis resulted in significant explanatory variables such as population of a county; obtaining LEED credits in material reuse, recycled material content, composite wood and agrifiber products, and regional material; and the density of Forest Stewardship Council (FSC)-certified product manufacturers within 161 km. The results of the study are expected to help improve availability of wood products by indicating potential green building marketing regions for wood product producers
INFLUENCE OF ENVIRONMENTAL CONDITIONS ON RELEASE RULES OF FERTILIZER FROM WOOD RESIDUE SLOW-RELEASE FERTILIZER SHELL
Get PDFSlow/controlled-release fertilizer is a kind of fertilizer that controls or slows down the nutrient release rate according to a specific release rate or release period. The development and application of slow/controlled-release fertilizer is highly valued all over the world because of its benefits. However, the materials used for the fertilizer coating are mostly difficult to degrade, causing many negative effects to the environment. Wood is a porous material that could be used as a coating material through which fertilizers could infiltrate. In addition, a shell glued with adhesives could degrade in soil because of the loose structure, providing another channel for infiltration of fertilizer. As a kind of environmental friendly material, a wood residue fertilizer shell could be used to provide fertilizer for trees, flowers, and other plants. Toona sinensis wood residues were used as the raw material to manufacture a slow-release fertilizer shell using thesecondary molding method. The influence of external environmental conditions such as temperature andrainfall on the release rules of fertilizers from shells were studied through artificial rainfall simulation. Results showed that release rules were similar in three sets of rainfall. The release amount increased quickly at the early stages and then decreased gradually. Also, the release amount changed as rainfall increased. Temperature also had a major influence on release rate of fertilizer from the shell. Generally, the release rate of fertilizer in the shell increased with increase of environmental temperature. The release amount kept relatively stable at lower temperatures. This study indicated that the wood residue shell could slow down the release of fertilizer. Both rainfall and temperature had a great influence on the release rate of fertilizer from the shell
EFFECT OF HIGH TEMPERATURE AND HIGH HUMIDITY TREATMENT ON BENDING PROPERTIES OF WOOD
Get PDFJapanese cedar (Cryptomeria Japonica D. Don) 110 110 1000-mm green boxed-heart timbers were dried under high temperature (110-140C) and high humidity (0.01-0.24 MPa gauge pressure) conditions until the weight remained unchanged. Then strength properties were examined. Wood became brittle because of the high temperature and high humidity treatment. We hypothesize that the wood was seriously damaged by hydrolysis because of the long treatment time used in this study and that the large cross-sectional area and high set gauge pressure lengthened the time of water loss from the wood. We considered viscosity and plasticity, rather than elasticity, to be the main factors that contributed to the decrease of work for rupture
EFFECTS OF WOOD PARTICLE SIZE AND TEST SPECIMEN SIZE ON MECHANICAL AND WATER RESISTANCE PROPERTIES OF INJECTED WOOD–HIGH DENSITY POLYETHYLENE COMPOSITE
Get PDFThe objective of this study was to evaluate mechanical (tensile modulus and strength and flexural modulus and strength) and physical (water absorption and thickness swelling) properties of wood–plastic composites made from industrial wood particles used for manufacturing three-layer particleboards and highdensity polyethylene. The effects of wood particle (WP) size (0.25-0.5, 0.5-1, and 1-2 mm) and test specimen cross section (4 10, 6 15, and 8 20 mm2) were investigated. Mechanical properties increased with increasing WP size because of the higher aspect ratio of larger WPs. Composites with larger WPs had lower water resistance. The values of both mechanical and water absorption properties derived from specimens with a larger cross-sectional area were lower than those derived from specimens with a smaller cross-sectional area
Chemical Suppliers’ Perspectives and Impact on Innovation in the Wood Treating Industry
No full textRecent challenges to forest sector firm competitiveness have driven interest in innovation to create a competitive advantage. Suppliers are a major source of innovation for forest sector firms, yet little study has been done on their role in the innovation process. Using a qualitative case study approach, we explore how chemical companies perceive innovation in the wood treating industry and how they feel they impact innovation among wood-treating firms. Our findings indicate that chemical company managers view the wood-treating industry as conservative and not particularly innovative. Additionally, retailers play a hampering and directing role regarding innovation in the industry. Chemical company managers feel that they have an important impact on innovation within their customer firms, partially because they see limited possibilities for differentiating wood products without value-added additions, such as chemical treatments. Currently, various mechanisms for coloring wood products, along with standard chemical treatments, are the focus of innovation efforts. Chemical company managers also view their role with customers as a problem-solver, providing a package of benefits following the total product concept. Finally, strong relationships between chemical suppliers and key innovative customers play an important role in creating and implementing innovations in the industry