Plastic lumber is a plastic form of lumber made of virgin or recycled plastic. It is mostly made of plastic and binders such as fiberglass or rebar; not to be confused with wood-plastic composite lumber. Widely employed in outdoor decking, it is also used for molding and trim and garden furniture such as park benches. Resistant to cracking and splitting when appropriately installed, plastic lumber can be molded with or without simulated wood grain details. Even with a wood grain design, plastic lumber is still easy to distinguish visually from natural timber: the grains are the same uniform color as the rest of the material. Manufacturers claim plastic lumber is more environmentally-friendly and requires less maintenance than wood/plastic composites or rot-resistant wood. Commercially available polyvinyl chloride fiberglass composite lumber sold for decking meets stringent fire code standards. Because plastic lumber can displace wood timber (as harvested by forestry), it can be a carbon negative and a carbon capture and utilization technology. Plastic lumber is composed of virgin or waste plastics including HDPE, PVC, PP, ABS, PS and PLA. The powder or pellets are mixed to a dough-like consistency at roughly and then extruded or molded to the desired shape. Additives such as colorants, coupling agents, stabilizers, blowing agents, reinforcing agents, foaming agents, and lubricants help tailor the end product to the target application. The material is formed into both solid and hollow profiles or into injection molded parts and products. Resin, regrind, and most of the additives are combined and processed in a pelletizing extruder. The new material pellets are formed in a mold and cooled. Plastic lumber can be molded to meet almost any desired spatial condition, a major advantage over wood. It can also be bent and fixed to form strong arching curves. Plastic lumber works like wood - it can be shaped, drilled, and cut using conventional woodworking tools.
Matthieu Wyart, Marko Popovic, Valentin Camille Druelle