Study On The Preparation And Properties Of Wood-Plastic Composites

The development, application, molding technique and preparation process of Wood-Plastic Composites (WPC) at home and abroad were summarized. The WPC composed of recycling plastic and wood powder were prepared by using single screw extruder and mould pressure method.1. The wood powder was pretreated by silane coupling agent, titanate coupling agent and sodium hydroxide. The effects of the pretreating agent and its adding amount and filling quantity of wood powder on the flexural strength of WPC were researched. The following conclusions are obtained: 1) the result of wood powder pretreated with silane coupling agent is the best among three methods. When the silane coupling agent is less than 4% , the flexural strength of the WPC become larger with the silane coupling agent, but basically has no change while the amount over 4%; 2) The flexural strength of the WPC reaches 30MPa while silane coupling agent content is about 4% and the wood powder content is about 50%.2.The WPC samples were prepared by single screw extruder at 150～160℃and repeated 2 or 3 times, while silane coupling agent content is about 4%, and the wood powder content is about 50%. By studying the effects of processing parameters on flexural strength of WPC, the following conclusions are obtained: 1) the flexural strength of wood-plastic composites first increases with temperature in the condition of 150～190℃,it reaches maximum at 170℃and then decreases; 2) the flexural strength of WPC increases and reaches maximum at 60min and then decreases slowly in the range of 30～90min; 3) the effect of pressing on the flexural strength of WPC is not obviously. The ideal parameters for preparing WPC are: in the conditions of 170℃, 5MPa and 60min.3. The size, quality and flexural strength WPC samples kept in 20℃water for 24 hours were measured. It was shown that:1) the average dimensional change of WPC is only 0.27%;2) the average water-absorbing rate is about 0.19%;3) the flexural strength of WPC basically has no change. As a result, the WPC has good water resistance properties.4. The flexural strength of WPC samples treated for 1h at different temperature was studied. It is shown that the flexural strength of WPC decreases slightly with temperature in -20℃～60℃, but all reaches 30MPa. Therefore, the WPC has good properties of cold temperature resistance and heat resistance.5. By the metalloscope investigation of WPC, it was found that plastic was uniformly distributed in composites and integrated well with wood powder.