Wood and Fiber Science (E-Journal)
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ANATOMICAL, PHYSICAL AND MECHANICAL PROPERTIES OF TRANSGENIC LOBLOLLY PINE (PINUS TAEDA L.) MODIFIED FOR INCREASED DENSITY
Full text linkTraditional breeding methods are often constrained by the reproductive cycles of tree species and the difficulty in achieving significant improvements to complex traits; therefore, genetic manipulation of complex traits such as wood properties has the potential to resolve those issues. The objectives of this study were to analyze MOE, MOR, and the physical and anatomical properties of 2- to 3-yr-old field-grown transgenic Pinus taeda trees modified for increased density. This investigation consisted of a total of 55 sample trees in two separate experiments. Transgenic trees from sets OX41 and OX55, modified for increased density using two variants of the same HAP5 gene, exhibited higher mechanical properties with smaller stem diameter and tracheid lumen diameter than their set of control trees. In addition, set OX55 exhibited increased cell wall thickness. In the second experiment, the transgenic group WVK249, modified for higher density using an unrelated MYB gene, exhibited similar diameter growth and increased cell wall thickness and lower lumen/cell wall ratios but no change in mechanical properties compared with its control
Study on the Swelling Characteristics of Bamboo Based on Its Graded Hierarchical Structure
Full text linkTo understand the swelling characteristics of bamboo under its gradient structure, different parts of bamboo specimens have been soaked in solutions of different electrolytes. The results showed that the swelling extent of bamboo in solution is mainly influenced by chemical activity and molecular dimension of the solute. The dimensional increase in bamboo after swelling is mainly observed in the tangential and radial direction, and the largest dimensional increase as a result of swelling occurred in intermediary bamboo. High-concentration strong electrolytes will cause a certain degree of recrystallization in the bamboo specimen, especially in intermediary bamboo, resulting in an increase in its mass. In summary, the conclusion is that the removal of wax and tabaxir before swelling and the avoidance of using strong electrolytes as swelling solutions tend to improve the efficiency of swelling bamboo
Bending and Creep Deformation of a Wood-Based Lightweight Panel: An Experimental Study
Full text link When wood exposed to long-term load, creep deformation can occur, because of its viscoelastic characteristic. The aim of this study was to increase the understanding and knowledge of creep deformation on a wood based lightweight panel of sandwich type, to see if this type of panel had similar properties for creep as solid wood has. This was done through a study based on experiments. The studied panel consisted of two face sheets of beech wood and a core of pine wood struts cross-glued to the face sheets. A solid beech panel was used as a reference. There were in all 27 samples of panel models; the densities of the lightweight panels varied from 165 to 297 kg/m3 compared with the solid panel of 705 kg/m3 density. The study consisted of two parts, a bending test and a creep test. The bending test was used to determine the maximum failure load for the panels. For the creep test, a 30% failure load was used. When the results from the bending tests were ranked to load capacity in relation to density, the results for the lightweight panel varied from 9.0 to 18.0 m4/s2, compared with the value of the reference panel at 27.3 m4/s2. This measured how effective the panel was in withstanding bending loads in relation to density. However, it did not say that the panel with the highest value also took the highest load in absolute terms. If the creep deformation is instead ranked in relation to density, the results for the lightweight panel varied from 10.4 kg/m to 33.7 kg/m. compared with the value of the reference panels at 45.5 kg/m. As with the bending tests, these values show a ranking of how effective the panels are to resist creep deformation in relation to density.
EXPERIMENTAL RESEARCH ON MECHANICAL PROPERTIES OF LAMINATED POPLAR WOOD VENEER/PLASTIC SHEET COMPOSITES
Full text linkIn this study, to improve the structural applications of wood plastic composite (WPC) according to its relatively lower MOE, wood veneer and plastic sheets were laminated to form laminated WPC (LWPC). Bonding performance tests were conducted to determine the effects of coupling agent and processing on bonding performance between wood and plastic, followed by mechanical properties tests. The bondlines between wood and plastic were examined using scanning electron microscopy (SEM). The results showed the following. 1) Delamination of untreated LWPCs was converted into wood fracture by adding a coupling agent. 2) The bending strength and tensile strength are both higher than those of the conventional WPCs, and the MOE of parallel multilayered LWPCs was significantly increased. The parallel multilayered LWPC with a density of 0.6 g/cm3 and wood-to-plastic ratio of 3:1 had an MOE of 11,490 MPa, and the bending and tensile strength were 40.36 MPa and 31.47 MPa, respectively. 3) SEM indicated that a strong interfacial connection in LWPC was obtained. This study demonstrated that the configuration of LWPC in combination with laminated veneer lumber and conventional WPC technologies is an effective method to improve mechanical properties. The LWPC can be used as a load-bearing material in timber structure
WOOD AND PLYWOOD QUALITY CHARACTERIZATION OF NEW AND ALTERNATE SPECIES AMENABLE FOR COMPOSITE WOOD PRODUCTION
Full text linkIndia is one of the robust consumers of engineered wood products and the raw material demand for engineered wood production is increasing at an alarming rate. Currently the plywood industries in the country depends only on few species and demands screening of alternate and species amenable for plywood production. Therefore studies were conducted to characterize the physical and mechanical properties of eight different tree species viz., Toona ciliata, Chukrasia tabularis, Acacia hybrid, Neolamarckia cadamba, Acrocarpus fraxinifolius, Swietenia macrophylla, Casuarina equisetifolia and Mitragyna parvifolia which are potential tree components in Agroforestry system. The physical properties like density exhibited wider variation between the species. In general, all species exhibited medium to high density values. The studies on veneer recovery indicated that barring Mitragyna parvifolia, all other species exhibited more than 50% veneer recovery and extend greater scope of adoption. Similarly the veneer quality exhibited wide differences and several species registered face veneer quality. The analysis of mechanical properties of plywood made out of all eight species indicated that the Modulus of Elasticity (MOE) was well within the acceptable range and the Modulus of Rupture (MOR) was on higher side which indicated that these species could play a vital role in manufacture of medium to high density plywood
Durability Assessment of Western Juniper from Five Different Growing Regions
Full text linkThe relationship between extractives content and resistance to fungal attack was examined in heartwood samples of western juniper (Juniperus occidentalis) collected from across the growing range. Mass losses of juniper samples exposed to Trametes versicolor were generally low and indicated that this species would be classified as highly durable, while mass losses for samples exposed to Gloeophyllum trabeum were higher and suggested that juniper heartwood was slightly less resistant to this fungus. Extractives levels were generally poorly correlated with decay resistance, but there were substantial differences in extractives content between samples from different geographic areas. The results suggest the need for further evaluation of a wider range of samples to better determine the relationship between extractives and decay resistance
EVALUATION OF LUMBER FROM DECONSTRUCTED PORTLAND RESIDENTIAL BUILDINGS
Full text linkPortland, Oregon was the first U.S. city to implement a deconstruction ordinance in 2016. Although salvaged lumber from deconstructed dwellings can have high demand, the market for small-sized lumber is near saturation. New applications for this material are required for market development, industry diversification and the possible expansion of the deconstruction ordinance. Its use in mass timber is an option, but presently no wood property information exists for lumber from deconstructed dwellings inhibiting its use for structural purposes. Density and dynamic MOE (E) of 265, 38 mm x 89 mm (2 x 4) pieces of salvaged Douglas fir (Pseudotsuga menziesii) lumber were determined using a Metriguard Model 340 E-Computer. Additional data collected included sample dimensions, weight, and visual appearance. Over 50% of samples had a calculated stiffness comparable to the highest structural design grade for Coastal Douglas fir lumber. The presence of knots and damage, present in 66% and 59% of boards respectively, would likely downgrade boards, despite acceptable stiffness. Results show that 96% of samples were sufficiently stiff to meet minimum requirements for the manufacture of E3 grade cross laminated timber (CLT) panels and considering defects, this material is suitable for manufacturing CLT. Provision of wood property information for salvaged lumber is critical for market expansion and this work represents the first characterization of lumber from deconstructed Portland, OR dwellings