ULTRASONIC INTENSIFICATION OF ALKALINE TREATMENT OF FILLER IN THE PRODUCTION OF WOOD-PLASTIC COMPOSITE

In the manufacture of wood-plastic composites (WPC) based on polypropylene natural filler is the logical choice to reduce the amount of synthetic polymer, which not only reduces the cost of the final product, but also reduces the harmful effects on the environment. However the boundary surface between plastic and wood is weak, because the hemicelluloses contained in wood filler is easily decomposed at temperatures of the polymer melt, causing the formation of micro-cavities within the composite. In addition the wood lignin influences the performance characteristics of the, greatly speeding up the discoloration of WPC outdoor. Consequently, in order to improve its performance characteristics in the WPC the preliminary reduction of the concentration of these components in wood filler is relevant. The article discusses the possibility of intensifying of alkali treatment of wood filler with the help of ultrasonic treatment. The decrease in the content of lignin by 20% and hemicelluloses by 24% is possible in the process of alkali treatment. It is established, that the additional influence of ultrasound increases the release of these components on the average in 2 times. Increasing the strength and modulus of WPC samples made with wood filler, subjected only to chemical treatment, is on average 18% and 10% respectively. Additional ultrasonic influence in the process of the alkali treatment improves the strength and elasticity on average by 25% and 13%. Thus, it is proved that the combination of alkaline and ultrasonic treatment of the wood will significantly affect the effectiveness of the preliminary chemical treatment of wood filler.