What is in Trex composite fencing?

Trex composite fencing is a combination of materials, primarily plastics and wood. The thermoplastic content (a type of plastic polymer that can be melted down and recycled almost indefinitely) is primarily polyethylene from reclaimed/recycled grocery bags and stretch film. The wood fiber is typically obtained from furniture makers and/or waste pallets, and is a mix of hardwood and softwood sawdust. The recycled/reclaimed portion of the product makes up approximately 95% of the material with roughly half of that content in plastic and the other half in wood. The remaining 5% is a combination of pigmentation and adhesives (proprietary glues to bind the wood and plastic).  The finished product is a decay-resistant, durable material that are extruded to create the profiles that make up a Trex fence.