Wood Polymer Composite Lumber

Wood–plastic composite (WPC) lumber has been marketed as a low-maintenance, high-durability product. Retail sales in the United States were slightly less than $1 billion in 2008. Applications include decking, railing, windows, doors, fencing, siding, moldings, landscape timbers, car interior parts, and furniture. The majority of these products are used outdoors and thus are exposed to moisture, decay, mold, and weathering. WPCs are composites made primarily from wood- or cellulose-based materials and plastic(s). The wood utilized is usually in particulate form, such as wood flour or very short wood fibers. Because of the thermal stability of wood, only thermoplastics that melt at temperatures equal to or below 200°C (392°F), which is the degradation point of wood, are utilized in the production of WPCs. Wood Polymer Composite Lumber

The most common plastics used for WPCs are polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC). The WPC blends can vary in percentage, with wood content up to 70%, but 50% wood/50% plastic is common. It was first thought that mixing plastic and wood together would result in plastic encapsulation of wood, thereby preventing both moisture sorption and fungal decay. However, after over a decade of use in outdoor exposure, issues have surfaced that are caused by wood decay, susceptibility to mold, and polymer degradation. After the first-generation products showed these problems, the industry began to address the performance issues by improving the formulations with additives, including fungicides, mildewcides, and photostabilizers. Further improvements are continually being investigated today. Researchers around the globe are currently working on understanding the fundamental mechanisms of degradation and on ways to improve WPCs.

As an industry, the manufacture of wood plastic lumber decking is less than 15 years old. It has experienced an annual growth rate of 30% during the late 1990s (ASTM 1999). Various extrusion processes are used to manufacture wood plastic lumber and some manufacturers, to reduce weight and material costs have adopted the manufacture of hollow cross-section profiles. Wood composite plastic lumber

The materials used to produce wood plastic composite lumber include thermoplastic resins, most notably, low and high density polyethylene, polypropylene and polyvinyl chloride. The polymers utilized typically need to have melting temperature that is below the thermal decomposition of wood (~225 degrees C).

The Wood Plastic Composite (WPC) Information Center provides technical and industry information about wood plastic composites which are also referred to as composite lumber or natural fiber thermoplastic composites. The Wood Plastic Composites information website could be helpful for composite lumber/ composite decking/ wood working business start ups, small-scale entrepreneurs, new wood working business ventures or for anyone who is interested in knowing more about wood plastic composites, composite decking, and natural fiber wood working businesses and markets. The WPC website includes information on producers of composite lumber or composite decking materials, suppliers to composite decking and railing manufacturers, composite testing and evaluation procedures for obtaining IAS Accredited code compliance reports, marketing, and about applications of composite lumber or timber plastic composite materials for infrastructure and building construction projects.

Wood plastic composites, generally produced using extrusion technology, are composed of natural fibers or wood in particulate form, thermoplastic resins (polyolefins) and additives such as lubricants, colorants and inorganics.

Natural fiber and wood plastic composite producers and suppliers can utilize the Wood Materials and Engineering Laboratory's consultation to obtain comprehensive guidance to processes, such as extrusion and injection molding, and product performance such as composite deck board and guardrail systems, composite lumber, plastic lumber, wood based products, and fastening systems. Outdoor Wood plastic plank