Physical and mechanical properties and fire, decay, and termite resistance of treated oriented strandboard

This study evaluated the effects of a number of chemicals on the physical and mechanical properties and fire, decay, and termite resistance of oriented strandboard (OSB) panels. Disodium octaborate tetrahydrate (DOT), boric acid (BA), melamine phosphate (NIP), and a BA/DOT mixture were sprayed onto the furnish at varying concentrations. The panels were tested for thickness swell, water absorption, modulus of rupture, modulus of elasticity, and internal bond strength according to the procedures defined by ASTM D 1037. All treated panels, except those treated with BA/DOT, were found to comply with CSA 0437 requirements for mechanical properties at a 2 percent concentration level. However, thickness swell and water absorption values were higher compared to CSA 0437 standard values. Laboratory decay tests showed that treated OSB specimens were well protected from both a brown-rot fungus (Fomitopsis palustris) and a white-rot fungus (Trametes versicolor). Weight losses in MP-treated OSB specimens were higher than those in boron-treated specimens. However, increased NIP content caused a decrease in weight loss. In termite tests, BA and DOT were more effective than NIP against Coptotermes formosanus. Contrary to decay test results, OSB specimens containing higher NIP concentrations showed lower resistance against termite attack. In a limited series of cone calorimeter tests, treatments did not substantially improve the fire performance of OSB. Of the treatments studied, the highest retentions of BA and BA/DOT provided some improvement in fire performance. DOT also provided some improvement but it was not commensurate with the amount of chemical added

A simulation study of the Japanese bō

A study on various aspects of the Japanese bo including the most effective way to hold a bo to strike an object, the region along the length of the bo to impact an object, and the best method of resisting an impact were studied with the aid of finite element analysis (FEA). The results offer a very interesting scientific insight into the Japanese bo, which is very useful for improving the techniques of using the bo to one’s advantage, and improving the design of the Japanese bo

Effect of various tire retardants on surface roughness of plywood

In this study the surface roughness of plywood treated with various fire retardants was investigated. Commercially manufactured veneer of Akaba wood (Tetraberlinia bifoliolata) was treated with borax, boric acid, monoammonium phosphate and diammonium phosphate, then experimental plywood panels were made from these veneer sheets. A stylus method was employed to evaluate the surface characteristics of the samples. Three main roughness parameters, mean arithmetic deviation of profile (R-z), mean peak-to-valley height (R-a), and maximum roughness (R-max) obtained from the surface of plywood were used to evaluate the effect of chemical treatments on the surface characteristics of the specimens. Significant difference was determined (p = 0.05) between surface roughness parameters (R-a, R-z, R-max) for four treatments and two retentions of fire retardants. Samples treated with 3% concentration of borax had the smoothest surface with 11.09 mu m R-a while the roughest surface was found for the samples treated with 6% boric acid having R-a value of 12.44 mu m. Results revealed that the surface quality of the panels reduced with increasing chemical concentration. (c) 2005 Elsevier Ltd. All rights reserved

Correlation Of Adhesive Strength With Service Life Of Paint Applied To Weathered Wood

INTRODUCTION In the absence of adhesion failure, paint on wood exposed outdoors gradually erodes. Degradation of paint by erosion may take a decade or more, depending on the degree of exposure to sunlight and moisture and the thickness and type of paint. While a paint system is eroding, it still protects the wood surface from degradation. Until this erosion process proceeds to the point where the primer begins to show, the paint surface can be renewed readily with an additional topcoat. With timely refinishing, painted wood can last for centuries (Feist & Hon 1984). If, however, the paint--wood interphase fails, the paint film will debond within a short time and the paint will blister, crack, and peel. This failure can result in damage to the wood surface and more difficult and costly refinishing. One cause of interphase failure is a degraded wood surface caused by weathering prior to initial priming with paint (Arnold et al. 1992, Boxall 1977, Bravery & Miller 1980, Desai 1967, Evan