Wood and Fiber Science (E-Journal)
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Evaluation of Four Surfacing Methods on Black Spruce Wood in Relation to Poly(Vinyl Acetate) Gluing Performance
Get PDFOblique cutting, peripheral planing, face milling, and sanding were used to surface black spruce wood prior to gluing with a two-component poly(vinyl acetate) adhesive. Surface roughness, anatomical features of surfaces, and glueline interfaces as well as the glueline shear strength before and after aging were evaluated. Oblique-cut surfaces presented no subsurface damage, little fibrillation, low roughness, thin gluelines, and little adhesive penetration. Peripheral-planed and face-milled surfaces both showed slight cell deformation and a higher level of fibrillation. The large number of cell lumens available and the fibrillation appeared to favor the penetration of adhesive as well as to increase surface roughness. Sanded surfaces were the smoothest, and their anatomical structures were the least visible of the four machining processes. These samples also showed more important subsurface damage, which limited the penetration of adhesive. For the glueline shear strength before and after weathering, no significant differences occurred among the surfacing treatments. The microscopic and topographic differences among the surfacing treatments were not sufficient to generate significant differences in glueline shear strength. Peripheral planing and face milling should be better alternatives with respect to productivity
Effect of Gamma Irradiation on Microcrystalline Structure of Phragmites Cellulose
Get PDFEffect of 60Co-γ irradiation treatment on cellulose structure originating from Phragmites communis trim (PCT) was investigated on the basis of irradiation doses of 0 to 2000 kGy at a dose rate of 2 kGy h-1. Scanning electron micrograph images showed that surface morphologies of PCT cellulose could become fragmented after being treated with 60Co-γ irradiation. Based on X-ray diffraction profiles, crystallinity and amorphous region of microcrystalline cellulose treated by irradiation were obviously changed. Fourier transform IR spectroscopy data indicated that a new characteristic peak corresponding to carbonyl (1734 cm -1) appeared after PCT cellulose was treated with 60Co-γ irradiation, which suggested that PCT cellulose was degraded after irradiation treatment
Book Review: A Compilation of Micrographs on Wood and Wood Products, by Norman P. Kutscha
No full textMoment-Curvature Analysis of Coupled Bending and Mechanosorptive Response of Red Spruce Beams
Get PDFIn this study, an expanded comprehensive numerical approach to predict hygromechanical behavior of beams is proposed that rigorously couples spatially varying time-dependent moisture content fluctuation with uniaxial stress-strain relations. The constitutive model, consisting of elastic, viscoelastic, and two mechanosorptive strain elements connected in series, was used in a layered moment-curvature flexural analysis. The procedure is numerical and is able to take into account effect of moisture content changes, different mechanosorptive behavior in tension and compression, and cross-sectional hygroexpansion. The overall trend and magnitude of predicted deflections are in good agreement with experimental results. Results demonstrated that complex beam behavior in a varying environment can be predicted by a simple model with well-defined material characteristics generated through relatively simple 18-h uniaxial experiments
Impact of a Regeneration Method and Vertical Position on Juvenile Wood Properties of Jack Pine in Northwestern Ontario
Get PDFThe effects of regeneration methods and vertical positions on three juvenile wood properties of 25-yr-old jack pine grown in the Boreal forests of northwestern Ontario were studied. Modulus of elasticity and modulus of rupture in static bending and specific gravity were determined from clear wood specimens of three vertical positions of trees selected from four stands that were aerial-seeded, Bräcke-seeded, planted, and postfire naturally regenerated. Juvenile wood properties among the four regeneration methods were not significantly different, however, they were found to vary significantly among the vertical positions for three of the methods: aerial-seeded, Bräck-seeded, and postfire natural stands. The wood properties of juvenile jack pine were quite variable, irrespective of the regeneration method, but there is a substantial potential in separating jack pine logs along the stem for various uses based on the regeneration method
Impact of Commercial Thinning on Annual Radial Growth and Wood Density in Plantation-Grown Black Spruce
Get PDFThis study examined ring width and density of plantation-grown black spruce 6 yr after commercial thinning (CT). Sample trees were from a 49-yr-old plantation receiving CT at age 43 yr near Kapuskasing, Ontario, Canada. There was a significant and positive effect on annual radial growth for heavy thinning (one of three rows removed) but not for light thinning (one of four rows removed). CT had little effect on wood density. Increased radial growth caused by thinning was mainly from an increase in earlywood width. Latewood proportion was not affected by thinning. With increasing tree diameter from 100-220 mm, ring width increased 0.93-2.19 mm, whereas ring density decreased slightly 523-487 kg/m3. Ring width decreased from 1.31 mm at stump height to 1.13 mm at 2.5-m height and then increased to 1.62 mm at 7.5-m height. From stump height to 7.5 m, ring density decreased steadily from 525-491 kg/m3. The effect of thinning depended on tree diameter and height position. This study suggests CT in black spruce accelerated radial growth but had little effect on wood density. Appropriate thinning intensity may target radial growth increase to trees of certain diameters
Development of A 3D Log Sawing Optimization System for Small Sawmills in Central Appalachia, US
Get PDFA 3D log sawing optimization system was developed to perform log generation, opening face determination, sawing simulation, and lumber grading using 3D modeling techniques. Heuristic and dynamic programming algorithms were used to determine opening face and grade sawing optimization. Positions and shapes of internal log defects were predicted using a model developed by the USDA Forest Service. Lumber grading procedures were based on National Hardwood Lumber Association rules. The system was validated through comparisons with sawmill lumber values. External characteristics of logs, including length, large-end and small-end diameters, diameters at each foot, and defects were collected from five local sawmills in central Appalachia. Results indicated that hardwood sawmills have the potential to increase lumber value through optimal opening face and sawing optimizations. With these optimizations, average lumber value recovery could be increased by 10.01% using the heuristic algorithm or 14.21% using the dynamic programming algorithm. Lumber grade was improved significantly by using the optimal algorithms. For example, recovery of select or higher grade lumber increased 16-30%. This optimization system would help small sawmill operators improve their processing performance and improve industry competitiveness
Microtension Test Method for Measuring Tensile Properties of Individual Cellulosic Fibers
Get PDFA microtension testing system was devised to measure mechanical properties of individual cellulosic fibers. To avoid specimen gripping and to enhance fiber alignment during testing, a self-aligning ball and socket gripping assembly was used in the microtensile tester design. A resolution of 0.098 mN was obtained for the tensile load measurement with this microtensile tester. Fiber strain was determined from high-precision stepper motor movement with 0.078-μm resolution or by in situ video photography. Cross-sectional areas of a single fiber cell wall were measured with a confocal laser scanning microscope. Results obtained from this system indicated a linear stress-strain curve until fatal failure for mature latewood fibers, whereas juvenile latewood fibers displayed curvilinear stress-strain relationships. Average values of tensile strength, tensile modulus, and elongation at break were 1258 MPa, 19.9 GPa, and 6.6% for mature latewood fiber and 558 MPa, 8.5 GPa, and 9.9% for juvenile latewood fiber, respectively. These values agreed with published data. The preliminary test indicated the usefulness of the integrated environmental chamber for investigating moisture effect on fiber engineering properties, but further investigation is needed to obtain statistically significant data
Rectangular Mortise and Full-Width Tenon Joints in Ready-to-Assemble Light-Frame Timber Constructions
Get PDFResearch has demonstrated the suitability of light-frame timber constructions for ready-to-assemble housing. In this study, tests were conducted to determine the semirigid rotation characteristics of full-width mortise and tenon joints along with their moment capacity. Semirigid rotation factors varied from 12.27 × 10-6 rad/N·m for joints with 37.9-mm-thick × 146.1-mm-deep rails with 93.0-mm-deep tenons to 2.57 × 10-6 rad/N·m for 36.5-mm-thick × 254.0-mm-deep rails with 200.2-mm-deep tenons. Moment capacity of joints with full-width tenons varied from 9360 N·m for 36.5-mm-thick × 254-mm-deep rails with 200.2-mm-deep tenons to 2810 N·m for joints with 37.9-mm-thick × 146.1-mm-deep rails with 93.0-mm-deep tenons. Moment capacity of the joints could be closely estimated by regression expressions that take into account shear area along the neutral axis between the cross-pin and the end of the tenon and shear area of the relish itself