Plastic wood composite materials mainly use polyvinyl chloride (PVC) and polyethylene (PE) as the matrix. Compared with PVC decking, the compatibility of low-polarity with wood powder is worse, and the interface compatibilization is more important; but the melt viscosity of PP is not large and the sensitivity to temperature changes is not high, compared with PVC-based plastic wood composites Easier to process; Compared with PE, PP has lower density, higher surface hardness and wear resistance. Therefore, PP-based plastic wood composites can be used in fields with higher performance requirements. At present, PP-based plastic wood composite materials have been more and more researched at home and abroad. The focus of research is mainly on how to improve the interface compatibility of PP and wood fiber, the mechanical properties of composite materials, and how to use more effective processing techniques and equipment. Improving the interface interaction with wood materials is a key technical issue to improve the performance of composite materials. The main ways to compatibilize the interface of plastic xwood composites are the use of compatibilizers, wood materials or surface modification.

Properties of PP-based plastic wood composites

The main influencing factors of the performance of plastic wood composites include the type, amount, particle size, surface modification of wood materials, etc.; the current performance of plastic wood composites mainly focuses on tensile strength, bending strength, and impact strength In terms of weather resistance and flame retardancy, PP-based plastic wood composites have poor impact resistance, and improving impact resistance is one of the research focuses.

The influence of wood materials on physical and mechanical properties

Wood materials are used as fillers, and it is obvious that the more filled the better for industrial production. However, due to the compatibility problem between the resin and plant fiber, the filling amount of wood material must have an optimal value, and the size of wood material also has a great influence on the performance of composite materials.

Plastic Wood Composite Materials Develop Towards High Attachment Value
Impact of impact modifiers on performance

PP has high crystallinity, poor ability to deform and absorb energy, and is brittle, especially at low temperatures. Therefore, it is necessary to toughen PP-based plastic wood composites. Modifiers used for toughening PP plastic wood composites include EPDM, styrene-butadiene block copolymer (SB) S and so on. That is, the application of plastic wood composite materials in construction and other industries is growing rapidly, and other properties such as weather resistance and flame retardancy are also important parameters to measure their applications.

Non-polarization modification treatment of wood fiber surface

The wood fiber is modified by physical or chemical methods to “non-polarize” the surface, which can reduce the polarity difference between wood fiber and plastic and improve compatibility. The physical methods include low-temperature plasma treatment, heat treatment and other methods, but there are many influencing factors, the operation requirements are higher, and the commercial production is more difficult.

In order to expand the application field of PP-based plastic wood composite materials, it is urgent to improve the structure and function of composite materials, so that the products will develop from low added value to high attached value (such as interior decoration materials). The key to the structuring, functionalization and high-grade of plastic wood composites is to strengthen the research on the interaction between wood flour and plastic; comprehensively use modern research methods to investigate the compounding laws between fiber resins, such as interphase chemical bonds, interphase structure, and interface acid-base reaction The systematic study of phenomena such as surface wetting can make the blending and compounding theory of wood flour filling be established and perfected as soon as possible. In addition, due to the use of larger amounts of additives to improve processing performance and product durability, the formulation has become more and more complex, which is of great significance to the study of avoiding side effects among additives. In short, PP-based plastic wood composite material is an environmentally friendly material with promising prospects, and its processing technology will become increasingly mature and diversified.

Keywords：

plastic wood composite materials

PVC-based plastic wood composites

wood fiber surface

PP-based plastic wood composites