Effect of wood particle size on the water absorption of wood-plastic composites

Abstract

The main aim of this paper is to present the research findings which come out from the experimental determination of the influence of input raw material properties and composition on the water absorption of wood-plastic composites. During the WPCs production, important raw material parameters such as wood sawdust particle size, wood/plastic concentration ratio or type of plastic matrix can be recognized. In this research study, the aim was to produce WPCs of an acceptable and competitive level of quality which is determined from the final mechanical properties of WPCs. Particle size of wood sawdust used for production of WPC has significant influence on mechanical properties of composites and also on other important properties (water absorption, hardness, frost resistance, etc.). Using a variety combination of influencing variables the final quality of composites and also the operating parameters of the injection molding press can be improved. Their effect can be seen from the quality indicators and from the operating parameters of the injection press which has a direct impact on the production costs. The paper deals with the determination of the impact and the relationship between the input wood sawdust particles sizes, wood/plastic concentration ratio and water absorption of composites. By side intention of authors is to determine the possibilities of waste raw materials usage. The experimental research findings were obtained using a semi-operational injection molding press where the injection is provided by a working screw. As the input raw material, spruce sawdust, HDPE plastic matrix and recycled HDPE, represented by lids from PET bottles, was used. The effect of the input wood sawdust particle size on water absorption was determined according to a combination and default levels of wood/HDPE concentration ratio, using recycled HDPE instead of virgin HDPE and particle size of wood sawdust.