Chemical and physical changes required for producing dimensionally stable wood-based composites

Summary High temperature (240°C) contact treatment was shown to be a very effective method of stabilizing panels bonded with heat resistant adhesive. Chemical analyses of post treated boards indicate that chemical changes of the wood components due to contact heat treatment were negligible. The results support the concept that high temperature post treatment of boards at temperatures above the softening points of lignin and carbohydrate components, caused plastic flow in situ which relieved internal stresses built up during hot pressing. Consequently, springback in wood-based composites diminished leaving panels much more stable than conventional products. Also, dimensionally stable wood-based composites had a better inherent ability to withstand severe exposure conditions than the regular boards.The authors wish to thank G. Bastien and B. S. Lethbridge for technical assistance. One of the authors (W.S.) is grateful to the Fonds zur Förderung der wissenschaftlichen Forschung, Vienna, Austria for financial support (Proj. No. J0128C)