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Plastic wood composite materials are composite materials made by melting and mixing wood or non-lignocellulose and plastics. They have many advantages such as environmental protection, light weight, high strength, and low cost. They are widely used in construction, municipal administration, and automobile transportation. The development of high-performance plastic wood composite materials can not only meet the needs of social and economic development, but also realize the high-efficiency and high-quality recycling of solid wastes such as waste plastics, wood chips, and straw fibers. It is of great significance to promote ecological protection and build a circular economy.
Wood or non-lignocellulosic surfaces often contain a large number of alcoholic and phenolic hydroxyl groups, which are easy to form intermolecular or intramolecular hydrogen bonds, with strong polarity and water absorption. The polyolefin resin commonly used in plastic wood composite materials is usually a non-polar substance with low polarity, poor wettability and compatibility with the more polar cellulose, and it is not conducive to the uniform dispersion of cellulose in the matrix resin. This results in poor interface bonding and low fatigue strength, making it difficult to meet the requirements of high-end applications. In actual production, the filling amount of wood flour is very high, and the fineness is more than 100 mesh. Under high filling and high fineness, the dispersibility and interface bonding force of wood flour have a more significant impact on the material properties. Enhancing the interfacial bonding force between cellulose and plastic and improving the dispersion of cellulose in the plastic matrix are the key ways to improve the mechanical properties of plastic wood composites, which have attracted the attention of many researchers. Whether it is adding cellulose to the plastic matrix, surface modification of wood powder, or addition of interfacial compatibilizers, it will affect the rheology of the plastic wood composite system, and then affect the molding process of the plastic wood composite. Therefore, optimizing and improving the performance of plastic wood composites involves not only the material components, but also the molding process. It is necessary to comprehensively consider various influencing factors and comprehensively design the material components and molding process.