Wood and Fiber Science (E-Journal)
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STATIC BENDING STRENGTH PERFORMANCES OF CROSS-LAMINATED WOOD PANELS MADE WITH SIX SPECIES
Get PDFIn this study, with the view to using effectively Korean small and medium diameter woods as structural materials, the cross-laminated wood panels were manufactured by using six species of Korean softwoods and hardwoods, and static bending strength performances were investigated for each species. The static bending strength performances of parallel- and cross-laminated wood panels increased in proportion to the density of species on the whole. The static bending strength performances perpendicular to the grain were improved by cross-laminating the longitudinal direction lamina in the core, the extent of the increase was higher in softwoods than in hardwoods. The measured modulus of elasticity (MOE) of parallel-laminated wood panels and cross-laminated wood panels perpendicular to the grain of face laminae had a little difference with those calculated from true MOEs of individual laminae. However, the measured MOEs of cross-laminated woods parallel to the grain of face laminae were much lower than the estimated MOEs owing to the effect of deflection caused by shear force. The percentage of deflection caused by shear force versus total deflection (Ys) showed high values of 9.8%~34.0%, and the cross-laminated wood panels made with softwoods were found to be markedly higher than those made with hardwoods
EFFECT OF SPECIMEN WIDTH WHEN EVALUATING LABORATORY-MANUFACTURED, FIRE RETARDANT-TREATED STRANDBOARD
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3D VISUALISATION OF SPIRAL GRAIN AND COMPRESSION WOOD IN PINUS RADIATA WITH FLUORESCENCE AND CIRCULAR POLARISED LIGHT IMAGING
No full textTo visualise the development of spiral grain in young pine trees, a novel technique was developed that is based on tracking the orientation of axial resin canals. 60 µm-thick complete serial transverse sections covering a stem length of nearly 10 mm were imaged at high resolution with a professional flatbed scanner using circular-polarised transmitted light. Lignin autofluorescence from compression wood in these sections was also imaged with a stereo-fluorescence microscope, using blue excitation and green fluorescence. Images were aligned and canals detected with ImageJ macros. A series of image processing steps were applied to the image stack and only resin canals were identified as black dots in the resultant image stack which was used to generate a 3D view of spiral grain using a plug-in ‘3D Viewer’ in ImageJ. The 3D visualisation showed the organisation of resin canals and spiral grain inside the wood. 3D reconstruction to show the compression wood was made from overlays of the fluorescence and the scanner images. Imaging confirmed the rapid onset of spiral grain, with a near vertical adjacent to the pith reorienting to a strong left-handed spiral within the first year of growth. There were fewer canals in the compression wood which appeared to be straighter than the twisted canals found elsewhere. This new method provides new insights in to our understanding on the formation of spiral grain and compression wood and a possible link between their occurrences
CELL WALL DOMAIN AND MOISTURE CONTENT INFLUENCE SOUTHERN PINE ELECTRICAL CONDUCTIVITY
Get PDFRecent work has highlighted the importance of movement of chemicals and ions through the wood cell wall. Movement depends strongly on moisture content and is necessary for structural damage mechanisms such as fastener corrosion and wood decay. Here we present the first measurements of electrical resistance of southern pine at the subcellular level as a function of wood moisture content by using a 1 µm diameter probe. Measurements were taken with the probe contacting the S2 layer of the cell wall and the cell corner compound middle lamella in the latewood and the cell corner compound middle lamella in the earlywood. The resistance decreased with increasing relative humidity in all locations. The resistance decreased more rapidly with relative humidity in the S2 layer than in any of the middle lamellae. These results give insight into how some moisture-dependent wood properties affecting ion movement may be partitioned across cell wall layers
ENERGETICS APPROACH TO FATIGUE BEHAVIOR OF WOODEN JOINT USING DOUBLE-SIDED ADHESIVE TAPE
Get PDFThe authors have previously studied the possibility of the use of industrial double-sided adhesive tape as a method for jointing wooden panel to wooden framework. The mechanical performance of joints formed by such methods is comparable to that of nailed joint under static load conditions. However, the mechanical performance of such joints has not been evaluated under cyclic load conditions. This study was conducted to investigate this aspect of their performance. Double-shear specimens were prepared by bonding wooden panel to wooden framework using two types of adhesive tape with different substrates. Specimens were also prepared with wooden dowels to strengthen their jointing performance. The joint specimens were subjected to cyclic shear loading testing. The results of the tests were analyzed from an energetics perspective, and the shear deformability of the specimens at failure was estimated. The test results indicate that both the specimens formed using adhesive tape and those formed using wooden dowels had fatigue properties comparable to nailed joint specimens. A tendency for the shear deformability caused by cyclic loading to increase with the stress level was observed. It was possible to estimate the shear deformability by evaluating the energy absorption capacity of the joints from an energetics standpoint
TECHNICAL NOTE: SUBTERRANEAN TERMITE RESISTANCE OF SMOKED GLUED LAMINATED LUMBER MADE FROM FAST GROWING TREE SPECIES IN INDONESIA
Get PDFAbstract. The purpose of this research was to determine the resistance of smoked glued laminated lumber (glulam) against subterranean termites (Coptotermes curvignathus Holmgren), using Japanese standard JIS K1571-2004. Glulam was made from fast-growing wood species, namely Acacia mangium (mangium), Maesopsis eminii (manii), and Falcataria moluccana (sengon). The glulam was constructed with either the same species for all layers or mangium as the face and back layers and a core layer of manii or sengon. Glulams were smoked for 15 or 30 days using smoke of mangium wood, and glulam preserved with imidacloprid and untreated glulam were prepared for comparative purposes. Mangium smoke was found to predominantly produce acetic acid, cyclobutanol, phenolic compounds, and other polycyclic aromatic hydrocarbons that improved glulam resistance to subterranean termite attack. Smoked glulam had the same resistance to subterranean termites as imidacloprid-preserved glulam and was much more resistant than untreated glulam. Glulam smoked for 15 days had the same resistance as that smoked for 30 days Keywords: Smoked glulam, Fast-growing tree species, Subterranean termite, GC-MS, preservation
FUNGAL DEGRADATION METHOD DEVELOPMENT FOR SMALL WOOD SAMPLES SUBJECTED TO CERIPORIOPSIS SUBVERMISPORA
Get PDFFungal pretreatment has been explored as a low-cost and an environmentally friendly method to increase the reactivity of lignocellulosic biomass prior to further processing for pulp and paper, biofuels, and biochemicals. Testing of genetically modified wood specimens is becoming increasing popular due to advances in the field of biomass research and the potential to greatly enhance the wood’s chemical and physical properties. However, experimental methods for small juvenile wood specimens is not well characterized. This research utilized sweetgum (Liquidambar styraciflua) to examine several variables in the inoculation and incubation procedure of small wood specimens degraded by white-rot fungus, Ceriporiopsis subvermispora, to find which method results in a sufficient amount of biomass degradation and low variation between replicates. The variables examined include inoculation medium, wood particle size, and incubation container. Increased fungal growth, weight loss values, and significant reduction in variation of weight loss were observed when using the malt extract fungal culture to directly inoculate the wood samples and closing with loose caps, instead of filtering, rinsing, and suspending the mycelium and sealing with Parafilm
U.S. HARDWOOD LUMBER CONSUMPTION AND INTERNATIONAL TRADE FROM 1991 TO 2014
Get PDFAbstract. Apparent U.S. hardwood lumber consumption (developed from production, import and export data) was contrasted with estimated consumption based on employment data and lumber utilization coefficients. The two methods of measuring domestic consumption provided similar results, but the use of employment data allowed for a comparison of appearance lumber versus industrial lumber use. Consumption of both appearance and industrial lumber increased between 1991 and 2000 as imported lumber augmented domestic lumber production. Exports increased during the 1990s but at a lower rate than domestic consumption. Beginning in 2000, consumption of appearance lumber started to decrease because of globalization of the furniture industry followed by a decline in U.S. home construction. The 2008 to 2009 recession was associated with declines for all segments of domestic consumption and a decline in exports. Domestic consumption of appearance lumber continued at depressed levels until 2012. Exports and industrial consumption increased after 2009. In 2014, industrial users accounted for 51 percent of domestic lumber consumption and exports represented 37 percent of consumption of appearance lumber
IMPACT OF THREE ALTERNATIVE SURFACING PROCESSES ON WEATHERING PERFORMANCE OF AN EXTERIOR WATER-BASED COATING
Get PDFOblique cutting, face milling, and helical planing were used to surface black spruce wood prior to the application of an exterior acrylic water-based coating. Surface characteristics were assessed using an environment scanning electron microscope and coating performance was evaluated through pull-off measurements before and after a 3-year natural weathering exposure. Microscopically, oblique-cut surfaces were smooth with plateau-like areas, had a low level of fibrillation and few open lumens. Face-milled surfaces were characterized by a high level of fibrillation and numerous open lumens that favor coating spreading and penetration. Helical-planed specimens had an intermediate level of fibrillation and number of open lumens. After coating application, oblique-cut and helical-planed surfaces presented similar overall visual quality, whereas face-milled samples had an irregular appearance that degraded their quality. As a result, the latter were subjected to erosion during weathering exposure which further degraded their overall quality as well as pull-off strength. More specifically, face-milled samples had a significant inferior pull-off strength both before and after weathering. Oblique-cut specimens yielded higher initial pull-off strength but were associated with higher adhesion loss. According to the results, helical planing reduces adhesion loss of the coating studied over a 3-year exposure to yield a superior pull-off strength after weathering. Therefore, surfaces having a certain level of fibrillation still firmly attached to the surface and open lumens are desirable to increase mechanical anchorage of coating on black spruce wood surfaces