Treesearch

Resin acids in the diethyl ether extracts of Picea glauca, Pinus ponderosa and Pinus banksiana seed cones were identified by gas-liquid chromatography of their methyl-ester derivatives. For these seed cones, abietic, dehydroabietic and isopimaric acids comprised 63.7-80.5 % of the total resin acids identified. In P. banksiana, the resin acid composition of the seed cones was shown to be significantly different from that in either the leaves, bark or wood. Investigation of the role of resin acids in the apparent decay resistance of woody conifer tissues to white-rot fungi involved the...

In this paper, we consider the fatigue strength of wood structural members. That is, we develop a mathematical model for time-dependent strength under sinusoidal load. This work extends the model for time-dependent strength under constant load and ramp load derived previously by two of the authors. It is based on the statistical theory of the absolute reaction rate in a version favorably reviewed in the literature. Under the isothermal condition, the model predicts that the time at fracture is independent of stress frequency. The need to evaluate experimentally some of the model parameters...

Recycled newspaper fibers (ONP) are potentially outstanding nonabrasive reinforcing fibers with high specific properties. In this study, a high energy thermokinetic mixer was used to mix these fibers in a polypropylene (PP) matrix, and the blends were then injection molded in order to observe the tensile and impact strengths of the composites. A 40% (weight) of ONP in PP resulted in a tensile strength of 34.1 MPa and an unnotched Izod impact strength of 112 J/m. Small quantities of maleic anhydride-grafted polypropylene (MAPP) and acrylic acid-grafted polypropylene (AAPP) were used to...

Numerous organizations have conducted research to develop nondestructive testing (NDT) techniques for assessing the condition of wood members in structures. A review of this research was published in 1991. This is an update of the 1991 report. It presents a comprehensive review of published research on the development and use of NDT tools for in-place assessment of wood members. It examines the fundamental hypothesis behind NDT of wood, reviews several widely used NDT techniques, and summarizes results of projects that focused on laboratory verification of the fundamental hypothesis....

This work demonstrates the complexity of modeling wall and corner fires in a compartment. The model chosen for this purpose is the Ohio State University (OSU) room fire model. This model was designed to simulate fire growth on walls in a compartment and therefore lends itself to direct comparison with standard room test results. The model input were bench-scale data obtained from the ASTM Test Method for Heat and Visible Smoke Release Rates for Materials and Products (E 906). Six wood materials were tested in the bench-scale test and also in an ASTM room fire test (proposed method). The...

Phenol-formaldehyde (PF) resin is a widely used adhesive in the manufacture of wood composites. However, curing behaviour of the resin under various environmental conditions is not well known. A differential scanning calorimeter was employed to characterize the degree of resin cure in this study. Resin-impregnated glass cloth samples with varied moisture contents (0,31,71%) were exposed to an environment of controlled temperature (105,115,125,140°C) and relative humidity (41,75,90%) for a series of time periods (0-20 min). The samples were next conditioned to different levels of relative...

The research studies included in this review focus on the use of nonwood plant fibers for building materials and panels. Studies address (1) methods for efficiently producing building materials and panels from nonwood plant fibers; (2) treatment of fibers prior to board production; (3) process variables, such as press time and temperature, press pressure, and type of equipment; (4) mechanical and physical properties of products made from nonwood plant materials; (5) methods used to store nonwood plant materials; (6) use of nonwood plant fibers as stiffening agents in cementitious materials...

A survey was conducted of primary and secondary manufacturing firms that have at least one dry kiln and process approximately 2 million board feet or more of lumber annually. More than 1,500 surveys were completed, representing manufacturers in 43 states. According to survey respondents, approximately 5 billion board feet of hardwood lumber and 24 billion board feet of softwood lumber were kiln dried annually. Drying data were collected for 48 commercial species or species groups and volume information was reported by state and region. The 13-state southern region dried more than twice as...

This study was designed to determine if steam injection pressing used for fiberboard, particleboard, and flakeboard could be adapted to the pressing of plywood. Plywood panels were fabricated with and without adhesive and then pressed to determine the effects of steam injection Lime, steam injection pressure, and press pressure on heat transfer rate, moisture distribution, thickness loss, and adhesive-bond integrity. The time to reach 220°F (104°C) in the center glueline of five-ply, 0.5-inch- (12.7-mm-) thick Douglas-fir plywood was reduced 15 percent using certain combinations of steam...

This report is an informational report about four wood-based panel industries: particleboard, oriented strandboard, medium density fiberboard, and Southern Pine plywood. Items highlighted are trends in manufacturing and new plant costs, industry manufacturing capacity, and location. Recent data show the greatest amount of growth taking place in the oriented strandboard sector. Modest rates of growth are occurring in the Southern Pine plywood, particleboard, and medium density fiberboard sectors.