What is Wood Polymer Composite (WPC)?

Wood plastic composite is a hybrid material composed of up 70% natural wood and plastic fiber. Saw dust from fiber fillers like pulp, peanut hulls, and bamboo are mixed with new or waste plastic powder, from materials such as polyethylene, polyvinyl chloride, polypropylene, and acrylonitrile butadiene styrene. Once the materials are mixed together to achieve a relatively thick consistency, they are extruded.

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Material selection depends in large part upon the manufacturer’s preference, and is based on the general properties of each component as well as availability. Wood components are generally used in sawdust form or small fibers, and typically upto 70 percent of the final wood plastic composite. 

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Because of the high cellulose content from the wood, WPC assumes many of the same characteristics of wood and can be subjected to the same processes, including planning, drilling, and sanding. Screws, and other fasteners often achieve greater hold when used with WPC than with lumber, which results in WPC’s ability to use smaller fasteners to hold more. Additionally, WPC offers superior water resistance when compared to basic wood with minimal expansion. The lack of moisture present within WPC also results in resistance to decay. The ability of WPC to perform in high temperature environments is also better than that of wood.

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To achieve the varying characteristics listed above, the manner in which the wood is processed and interfacial adhesion must be controlled. The difference between the surface energy of the wood and the matrix of the plastic polymer determines the final physical properties of the composite, often requiring the addition of a coupling agent to enable strong interfacial adhesion. Coupling agents encourage dissimilar materials (such as plastic and wood) to form an alloy. Compatibilization can also be used, a process by which wetting is achieved within the mixture. There are several manners in which coupling and compatibilization can take place, including the modification of the fiber or polymer and the addition of coupling agents. Depending on the type of wood and plastic involved, different coupling agents and compatibilizers may be appropriate.

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PROPERTIES OF WPC