Polymer-Performance on the Dimensional Stability and the Mechanical Properties of Wood-Polymer Composites Prepared by an Electron Beam Accelerator

Abstract

The state of the art of polymers in wood and their performance were studied for the wood-polymer composites produced by electron beam irradiation. The balance between the enhanced dynamic modulus and the dimensional stability of the products were discussed to prevent the formation of fatigue cracks during a long exposure to repeated cycles of humid and dry weather. The particular action of the tight cross-linking bonds in enhancing the mechanical properties as well as the dimensional stability of the products was recognized with regard to the unsaturated polyester WPC. In this regard, an impregnation method in two steps was proposed for producing a polyester WPC fancy veneer with distinguished mechanical properties and dimensional stability: First, the styrene or acrylonitrile monomers were impregnated in the moisture preswollen veneers and polymerized under an accelerator. Then, the styrene/unsaturated polyester system was impregnated in the irradiated veneers successively and polymerized by the repeated irradiation. The improvements of the dynamic modulus and the dimensional stability of WPCs were coming from that polymers of WPC in the first step were formed in cellular parts and those in the second step were formed in the cellulosic chains.