Abstract: An extrudable composition comprised of waste polyolefins and an alkali metal bicarbonate salt/solid, saturated fatty acid foaming agent system, and a method for extruding such extrudable composition wherein the fatty acid/bicarbonate foaming agent system foams the waste polyolefins during the extrusion to produce end products which have qualities closely simulating natural lumber suitable for use as construction materials.

Abstract: Construction materials prepared from recycled polymeric material containing primarily polyolefins such as high density polyethylene, ultra high molecular weight polyethylene, low density polyethylene, linear low density polyethylene, and polypropylene homopolymers and copolymers are useful for profiled extruded forms such as fence posts, door frames, rails, railway sleepers, and other applications where lumber is conventionally employed. The compositions of the invention contain, in addition to the mixed plastic matrix, reactive compatibilizers, impact modifiers, and reinforcing agents. When desired, foaming agents may also be employed. The recycled mixed plastic materials have been subject to at least one high temperature processing step when used in their original application. Such plastics differ in physical and chemical composition from virgin material.