Treesearch

Recent studies on nondestructive evaluation (NDE) of logs have shown that a longitudinal stress-wave method can be used to nondestructively evaluate the modulus of elasticity (MOE) of logs. A strong relationship has been found between stress-wave MOE and static MOE of logs, but a significant deviation was observed between stress-wave and static values. The objective of this study was to investigate the effect of log diameter on stress-wave evaluation of MOE of logs and to develop a new stress-wave model by relating stress wave MOE to log diameter for static MOE prediction. A total of 201...

Dynamic modulus of elasticity (MOE) of a wood member is defined as the product of its density and square of stress wave speed. The dynamic MOE, which is highly correlated to the static MOE, is commonly used to estimate the load carrying capacity and serviceability of in-situ wood members. The stress wave speed can be estimated using ultrasonic, impact, or vibration techniques. However, nondestructive evaluation of density in place is more difficult than under laboratory conditions. Screw withdrawal resistance, one of the techniques that could be used to estimate the density, was examined...

Extracts of Phanerochaete chrysosporium cultures grown on birch or on a malt extract-peptone-glucose agar medium were analysed by HPLC. A major component from the two sources appears to be identical by HPLC and UV- visible spectrometry. The product isolated from agar-grown cultures was purified to apparent homogeneity and structure analysis by NMR indicates that the metabolite is the beta-resorcylate phanerosporic acid, consistent with previous characterizations. The possible role for the metabolite in wood metabolism is discussed.

The arrangement of anatomical elements in the cross section of a tree can be characterized, at least to a first approximation, with a cylindrical coordinate system. It seems reasonable that the physical properties of wood in the transverse plane, therefore, would exhibit behaviour that is associated with this anatomical alignment. Most of the transverse properties of wood reported in the literature were determined using test specimens with rectilinear geometry. We are interested in using test specimens that are geometrically compatible with the material organization of the tree to avoid...

The fungal resistance of high density polyethylene filled with 50% wood flour was investigated using laboratory soil block tests. Modifications to standard test methods were made to increase initial moisture content, increase exposure surface area, and track moisture content, mechanical properties, and weight loss over the exposure period. Mechanical properties decreased after 12 weeks exposure to Gloeophyllum trabeum and Trametes versicolor. However, irreversible damage due to water sorption made separating the effects of fungal attack and water sorption difficult. When compared on a dry...

Production capacities of all woodpulp mills in the United States are identified by location, ownership, and process type. For each mill, production capacity is reported for the year 2000 by process type; total mill capacities are also reported for 1961, 1965, 1979, 1974, and 1983. In addition, the report summarizes the recent history and current status of woodpulp production capacity in the United States.

Wood–plastic composites are being increasingly examined for nonstructural or semistructural building applications. As outdoor applications become more widespread, durability becomes an issue. Ultraviolet exposure can lead to photodegradation, which results in a change in appearance and/or mechanical properties. Photodegradation can be slowed through the addition of photostabilizers. In this study, we examined the performance of wood flour/high-density polyethylene composites after accelerated weathering. Two 24 factorial experimental designs were used to determine the effects of two...

New challenges to the durability of wood building materials have arisen in the U.S. The Formosan subterranean termite (Coptotermes formosanus Shiraki) now infests sizable portions of the U.S. south (Figure 1) and their range is extending. Heat treatments offer a unique opportunity for wood-based composites because many of the process techniques already employ various thermal applications and could be easily modified to design-in durability enhancements if specific benefits were understood. Information on resistance of oil-heat-treated wood against Formosan subterranean termites, however,...

Wood is one of the most versatile and widely used building materials. However, it is also biodegradable, and may be attacked by decay fungi or insects when used in some applications or geographic locations. Uses that allow the wood to frequently become wet, such as embedded posts or other exposed wood members, are familiar examples of applications where wood will degrade. Although moisture is the key to deterioration of wood, in some geographic locations there are insects that will even attack dry wood used indoors. Because it is biodegradable, wood used in applications where it may be...

Wood pressure-treated with chromated copper arsenate (CCA) wood preservative is commonly used for outdoor construction. Oxides of arsenic, copper, and chromium are bound in the wood by a complex series of chemical reactions, but a small percentage of these compounds are gradually released by leaching and weathering. Recent studies suggest that the release of these compounds can be minimized by applying finish to the surface of the treated wood, but little is known about how or to what degree finish properties affect release. This study evaluated the effects of water repellents in clear...