Study On The Molding Process And Properties Of Different Fills And Plastic-Based Wood Plastic Composites

Wood Plastic Composites(WPC) was widely used in architecture molding board, furniture industry, packaging transportation and so on because of its environment friendly and sustainability advantages. The research and application of composites had a great significance to sustainable development of China’s economic. In this paper, wood-fiber, bamboo-fiber, rice-husk fiber, rice-straw fiber and plastic films were respectively adopted as reinforcer and basis material. Based on orthogonal experimentation, the optimized molding process parameters and the optimized mixture ratio of raw materials were obtained by orthogonal analysis. A comparative study of mechanical properties and physicochemical properties of many kinds of WPC (different types and contents of fillers, PP/PE-LD/PE-HD films with printing ink or no) had been done by different molding technics conditions (Interactive layer-molding, mixing-molding). The wettability of the surface and wear resistance of the composites were also tested, and the compatibility and the microcosmic shape were observed by stereomicroscope. The results showed that:(1) The optimum molding process parameters of rice-straw fiber/PP composites: molding pressure was18MPa, molding temperature190℃, pressure-holding time was25min.(2) Mechanical properties was more excellent by adding the appropriate amount of coupling agent into the straw-powder, while using silane coupling agent KH570could be better than titanate coupling agent NDZ105.(3) The extent of the effect on properties by various factors was as follows:the content of rice-straw fiber>particle size>KH570addition (respect to dry weigh of rice-straw fiber), and the content of the straw-powder had a greater impact on its mechanical properties. With the straw-powder content increased, mechanical properties of the composites decreased gradually. However, moisture absorption, moisture content, water absorption and thickness swelling and24h water absorption had an increasing trend. Mechanical properties of the composites would be best when the content of the straw-powder was50%, the particle size was60mesh and KH570 addition was2%. Besides, physicochemical properties of the composites would be best when the content of the straw-powder was50%, the particle size was100mesh and KH570addition was4%.(4) Different plastic-based wood plastic composites (with printing ink or no) differed greatly in mechanical properties and physicochemical properties. Comprehensive mechnical property of rice-straw fiber/PP composites with no printing ink was better. But, rice-straw fiber/PP composites with printing ink had the lower water absorption and thickness swelling. Impact strength of rice-straw fiber/PE-LD composites with printing ink was better, but its comprehensive mechnical property was bad.(5) Composites filled with different fiber types had different performance(particle size:60mesh), the straw-powder/PP composites of which had the better mechanical property, bamboo-fiber/PP composites was the worse, but it had the better physicochemical properties.(6) Mechanical properties and physicochemical properties could be improved by the mixing-molding process, meanwhile, it was more effective when the content of fillers was50%-65%.(7) The mixing-molding process made the products waterproof, but the interactive layer-molding process made the products had good wettability of the surface. By the interactive layer-molding process, the conetent of fillers had significant effect on the wettability of composites’surface, but the type of plastic films was on the contrary. The wettability of the surface was enhanced by the increasing conetent of fillers.(8) Wear resistance of the composites decreased gradually with the straw-powder content increasing. The mixing-molding process was of benefit to improve the wear resistance (except for wood-fiber/PP composites). Bamboo-fiber/PP composites had attractive wear resistance.