Solutions for Wood Plastic Composite Material
WPC Decking Interface Compatibility Issues
Interfacial compatibility has always been the focus of research in wood plastic composite material. Wood powder is composed of cellulose, lignin, hemicellulose, extract, etc. These components contain a large number of hydroxyl groups, resulting in a strong surface polarity of wood powder, water absorption. As for plastics, the thermoplastics commonly used in the market of wood-plastic products are PE, PP, polystyrene (PS) and PVC. Except for PVC, the four major commonly used plastics are all non-polar. Even PVC is less polar than wood powder. This results in poor interfacial compatibility between wood powders and these thermoplastics. To change the interfacial compatibility of wood powder and plastic, the first step is to pre-treat the raw material by drying wood powder and plastic to reduce the proportion of water remaining in the composite.
The second is to modify the treatment, the general modification methods include physical modification and chemical modification. The physical modification includes physical processing, alkalization treatment, discharge treatment, etc. The principle of physical modification is to reduce the ratio of hydroxyl groups on the surface of wood powder and reduce the polarity of wood powder surface. Chemical modification methods include coupling agent treatment, compatibilizer treatment, graft modification, etc. At present, maleic anhydride graft polymer copolymer is the most widely used coupling agent in the market. Maleic anhydride graft polymer copolymer can not only react with plastic activity, but also with wood powder surface hydroxyl chemical reaction to form a covalent bond, reduce the polarity of wood powder surface. Coupling agent plays a good role in improving the interface compatibility of wood-plastic composite material, wood powder and plastic can be combined together, improve the mechanical properties of wood-plastic composite products.
WPC Decking Economic benefit problem
The wood plastic composite material in addition to the necessary components of wood powder and plastic, but also need some additives, such as processing modifier, colourant, plasticizer, compatibilizer, coupling agent, a foaming agent. This requires consideration of both cost and performance. Reducing the proportion of thermoplastics and increasing the content of wood powder in the composites can reduce costs, but it can also lead to performance degradation. Therefore, the formulation should be diversified and improved in the research and development process to maximize the performance and benefits.
Classification and source of raw materials
Currently, the recycled plastic on the market is basically a mixture, which will bring difficulties to the reuse of waste plastic. So in the recycling of plastic to broaden the plastic recycling types, refined plastic varieties. For fibre, some manufacturers now use a seasonal straw, cotton stalks, rice husks, etc., which requires the storage of raw materials to be considered. Although these materials are much cheaper than wood fibres, there are many storage problems.
WPC Decking Density problem
The density of wood-plastic composite products is generally twice that of wood products, and the corresponding production cost of wood-plastic products will also increase. Nowadays, the general method to reduce the density of wood-plastic composites is microcellular foaming technology. The main forming methods of microcellular foamed wood-plastic composites are continuous extrusion moulding and injection moulding. The application of foaming technology not only solves the problem of the high density of wood-plastic composite products but also improves the mechanical properties of the materials by passivating the crack tip of the foam structure and preventing the crack propagation.
Production equipment and processing technology
At present, the methods of producing wood-plastic products on the market include extrusion moulding, pressing moulding and injection moulding. However, the equipment used either continues the general production equipment of plastic or continues the general production equipment of wood, resulting in the processing and performance of wood plastic composite material are subject to many limitations. In recent years, many wood-plastic manufacturers have improved the equipment or customized foreign production of wood-plastic equipment.