Treesearch

A number of commercial panel products, primarily particleboard and hardwood plywood, were tested for their formaldehyde emission behavior using desiccator, perforator, and dynamic chamber methods. The results were analyzed in terms of the source of formaldehyde observed in the tests (free vs. hydrolytically produced) and the potential utility of the testa as product standards for boards in mobile homes. A greater than tenfold range of formaldehyde emissions was observed, well above and below levels that would be acceptable for proposed mobile home air levels. It was demonstrated that...

CROMAX simulates crosscut-first, then rip operations as commonly practiced in furniture manufacture. This program calculates cutting yields from individual boards based on board size and defect location. Such information can be useful in predicting yield from various grades and grade mixes thereby allowing for better management decisions in the rough mill. The computer program CROMAX was written in ASCII FORTRAN on the University of Wisconsin’s UNIVAC 1100/80 computer. The complete program listing is included as an appendix.

A finite element program is presented which computes displacements, strains, and stresses in wood members of arbitrary shape which are subjected to plane strain/stressloading conditions. This report extends a program developed by R. L. Taylor in 1977, by adding both the cubic isoparametric finite element and the capability to analyze nonisotropic materials. The computer subroutines developed by the author are listed in this report, along with both the details for incorporating them into Taylor’s program and the required user instructions.

Specimens of southern pine treated with pentachlorophenol (penta) in mineral spirits (dip treatment), penta in P9 type A oil and penta in methylene chloride (pressure treatments) were used to evaluate the efficacy of different types of coatings in suppressing the vaporization of penta from treated wood. The clear film-forming coatings, such as polyurethane and alkyds, were typically greater than 90 percent effective for specimens dip treated with penta in mineral spirits. Two-component (epoxy type) pigmented coatings were effective on specimens treated with penta in P9 type A oil. Coatings...

Efficient use of paper products involves using modern aspects of materials science and engineering mechanics. This implies the ability to determine simultaneously different components of strain at multiple locations and under static or dynamic conditions. Although measuring strains in paper has been a topic of interest for over 40 years, present capability remains limited to recording strain in a single direction and over gauge lengths exceeding 20 mm. Improved full-field methods are needed. Of several possible optical techniques, moiré demonstrates potential for full-field analysis of...

Solutions of D-glucose in dilute sulfuric acid were allowed to react under time and temperature conditions which simulated the production of glucose from cellulose. Under these conditions, glucose undergoes a number of reactions including isomerization, dehydration, transglycosidation, polymerization, and anhydride formation. The specific interest in this report was to investigate the reversible reactions which form “reversion products.” These products, which include di-and trisaccharides, anhydrides, and glucosides, provide a protection for glucose from decomposition, but the products are...

The analysis of size effect on bending strength of rectangular wood beams based on Weibull's theory of brittle failure has been expanded here to include tapered wood beams under arbitrary loading conditions. The mathematical formulations are expressed in terms of the two parameters in Weibull's model. These parameters must be determined experimentally for each wood species. Numerical data for Douglas-fir beams are presented in graph form, where necessary, for easy application by the design engineer. Design procedures are demonstrated by numerical examples.

A manually operated particleboard press was converted to a fully automatic, programable system with updated data collection capabilities. Improved control has permitted observations of very small changes in pressing variables resulting in the development of a technique capable of reducing press times by 70 percent. Accurate control of the press is obtained through an electrical servo activated press pump and pressure- and position-monitoring transducers. Position is repetitively accurate to within 20.002 inch under a no-load condition and to within ±0.005 inch under pressure. Line pressure...

The objective was to determine the relationship between the variables specific gravity (SG) and flake alignment and the dimensional stability properties of flakeboard. Boards manufactured without a density gradient were exposed to various levels of relative humidity and a vacuum-pressure soak (VPS) treatment. Changes in moisture content (MC), thickness swelling, and linear expansion were measured and used to develop regression equations. Under board saturation conditions resulting from VPS, dimensional movement could be defined as a function of SG without regard to MC. The relationship...

An impact stress wave was induced in the end of 2 by 6 lumber containing knots. Rather than a normal, perpendicular-to-the-axis profile in transiting by a knot, the stress wave tended to Iead in zones of clear wood in the direction of the slope of grain or slope of the annual rings and to lag behind the knot. Of three methods evaluated to time the stress wave, the "average" timing method was more consistent than other methods in flagging the 6-inch length containing a knot from adjacent clear wood 6-inch lengths. Stress wave modulus of elasticity (ESW) calculaled from the data tended to be...