Wood and Fiber Science (E-Journal)
Not a member yet
2592 research outputs found
Sort by
An Analysis of Appalachian Hardwood Products in the Chinese Market
Get PDFTo improve information on log and lumber trade between the Appalachian region of the United States and China, 50 Chinese firms identified as potential and current hardwood products buyers were surveyed using a stratified random sampling method from January to May 2008. A series of questions were posed on the importance of certain attributes of the US products and how to make the trading process more efficient. Sampled information included business activities, location(s), annual sales, product distribution of firms importing hardwood products, customer satisfaction, potential barriers to trade, principal sources of supply, product types, grades, and species of hardwood products imported from the United States. Results indicated that the Appalachian region of the United States is an important hardwood source and will continue to play an important role in the Chinese market. Red and white oaks were the most frequently imported species, followed by hard (sugar) maple, black cherry, soft maple, and ash. The Appalachian hardwood logs entered the markets largely in east and north central China, whereas the hardwood lumber importers were mainly distributed in east, south, and north central China. Some ongoing issues such as the impact of Russia's log tariff, the Lacey Act, and others on China's wood supply were also raised. The results should be helpful for Appalachian hardwood producers to further explore opportunities to promote their products in the Chinese markets
Effects of Conditioning Exposure on the pH Distribution Near Adhesive-Wood Bond Lines
Get PDFThe pH distribution near the adhesive-wood bond line in black spruce (Picea mariana) and Douglas-fir (Pseudotsuga menziesii) bonded with various acidic and alkaline adhesives was investigated. For alkaline adhesives, exposure to moderate to high RH conditions and to accelerated aging treatments such as vacuum-pressure-dry or water soaking resulted in diffusion of hydroxyl ions (OH-) away from the bond line and decreased alkalinity. A moderate increase of pH in the bond line was also observed for acidic adhesives, and under very wet conditions, hydrogen ions (H+), also diffused away from the bond line. Spruce and Douglas-fir samples exposed to strongly acidic and alkaline buffered solutions for 3 mon did not show appreciable changes in chemical composition by wet chemical analysis. FTIR attenuated total reflectance spectra of samples bonded with an alkaline adhesive and exposed to either dry or wet conditions showed dissociation of carboxylic acid groups in hemicelluloses (decreased absorbance at 1735 cm -1) to a distance of 150-300 μm from the center of adhesive bond lines. No effects on wood chemistry were observed around acidic adhesive bond lines. In summary, wood bonded with high-pH adhesives and exposed to wet service conditions rapidly reached moderate pH conditions in the bond line because of the high rate of OH- diffusion in wood and the acidic buffering capacity of wood. This mitigated the effects of high pH in these alkaline adhesives. A similar but less effective process occurred with acidic adhesives
Technical Note: The Suitability of Young Fast-Grown Radiata Pine Clones for Conversion into Vineyard Trellis Posts
Get PDFIn this note, we test the hypothesis that vineyard trellis posts of the required size and strength properties can be produced from young radiata pine trees obtained from clonal plantations established using a dense stocking of physiologically aged cuttings selected for fast growth, good straightness, above-average juvenile wood density, and fine multinodal branching. Radiata pine trees from four different clones were all large enough to be converted into vineyard posts when they were 6 yr old. Posts made from the fastest growing clone had below-average wood density and a high grain angle and were significantly weaker than commercial posts made from 14-yr-old thinnings. Another clone, however, produced posts whose average breaking load and modulus of rupture were only 8.6 and 9.2% lower, respectively, than those of commercial posts. Posts from this clone had a low grain angle and above-average wood density as well as fine multinodal branching. We conclude that the use of selected radiata pine clones for the manufacture of vineyard posts shows promise as an alternative to the production of posts from thinnings and suggest how the strength properties of posts from clonal radiata pine trees might be further improved
Technical Note: Characterization of In-Plane Compressive Properties of Plywood by IITRI and End-Loading Compression Tests
Get PDFPanel compression tests can be affected by the propensity of the thin cross-section to undergo axial buckling. Tests were conducted to measure Young's modulus, proportional stress limit, and compression strength in two edgewise directions using an end-loading compression method and an alternate method developed by the Illinois Institute of Technology Research Institute (IITRI). The IITRI method mitigates the potential for buckling without explicit restraint. Young's moduli obtained by the two methods agreed well. In contrast, the test methods had differences in the measurement of proportional stress limit and compression strength
Within-Tree Variability of Wood Color in Paper Birch in Québec
Get PDFColor variations in paper birch wood were examined in boards sawn from sawlogs from 168 trees harvested from two different stands. Approximately 2250 boards were sawn from the logs. The within-tree variability was considered by looking at the effect of log quality and log height class on board color. Results show that neither the log quality nor the log height class had a significant effect on the proportion of discolored wood on the surface of the board. However, these log parameters had an effect on the wood colorimetric variables. Log position in the tree was found to significantly influence sapwood yellowness as well as discolored wood luminosity and redness. Log quality on the other hand significantly influenced only one colorimetric factor, sapwood redness
Relation Between Moisture Sorption and Hygroexpansion of Sitka Spruce During Adsorption Processes
Get PDFMoisture adsorption processes carried out in successive steps at three increasing levels of RH (45, 75, 85%) at 20°C for Sitka spruce (Picea sitchensis Carr.) were studied. Moisture content and dimensional changes in radial and tangential directions of the specimens were measured and it was found that moisture changes were slower than dimensional. The modeling on this moisture-dimensional relationship, based on the idea of dividing sorbed water into two components having different effects on dimensional changes, not only shows a good agreement with experimental results, but also presents a new understanding of the mechanism of hygroexpansion of wood
Technical Note: Shrinkage Properties of Partially Cad-Deficient Loblolly Pine Lumber
Get PDFPartially cinnamyl alcohol dehydrogenase-deficient and wild-type loblolly pine (Pinus taeda) were studied for shrinkage properties. The study established no significant difference between these two genotypes. Results also showed that shrinkage of juvenile wood is significantly different from the corresponding shrinkage of mature wood only in the radial direction. Tangential shrinkage difference between juvenile and mature wood was significant when the uncorrected values were used but not when the true shrinkage values were used, thus highlighting the need to account for the effect of growth ring curvature on tangential shrinkage measurement of small-diameter trees
Toward a Process Monitoring and Control of a CNC Wood Router: Development of an Adaptive Control System for Routing White Birch
Get PDFAn adaptive optimization system for routing white birch was developed to control feed speed to produce a desired degree of surface roughness. The system consisted of an interconnected adaptive controller linked to a numerically controlled router. Online estimation of surface roughness was made based on directionalized measurement of sound pressure. By knowing the surface roughness at a given moment and its permissible limit, the adaptive controller was able to take decisive action to adjust the feed speed. The adaptive control system was able to detect changes in the surface quality and, as a result, vary the feed speed. Therefore, surface roughness was maintained below a predetermined level and productivity could be increased. Comparison with the resultant surface roughness when machining the same sample at constant feed speed confirmed the applicability of the adaptive control system for wood machining
In-Plane Permeability of Oriented Strand Lumber. Part II: Microscopic Investigation of Void Structure During Compression
Get PDFThis study investigated the changes of void structure in oriented strand lumber samples pressed to different densities using microscopic techniques. Specimens of five densities, 450, 550, 625, 700, and 800 kg/m3, were examined. A method for preparing a large sectional area of wood composites for examination in a light microscope was developed. It was able to retain the original void structure and to provide high-quality images for further investigation. Microscope slides mounted with thin cross-sections for each density were prepared and then examined using fluorescence microscopy. The size and quantity of interstrand voids decreased dramatically with increasing board density. The forming and deformation of interstrand and intrastrand (ie cell lumens) voids, including failure of cell walls and nonhomogeneous collapse of cells, were observed. Generally the vessels were compressed before fibers as a result of their difference in diameter and cell wall thickness. The variability of deformation between regions within a strand and between strands within a mat was high, due to differences in strand cutting orientation, heterogeneity of mat structure, and strand property variation created by its source in different positions on a tree stem and between trees