Extrusion of self-reinforced thermoplastic composites illustrated by high density polyethylene

Abstract

A method is described for solid state coextrusion of self-reinforced and transparent composites for high density polyethylene composed of core and sheath components. The high density polyethylenes are coextruded below their melting points. The cocylindrical composites have a high tensile modulus and strength, a high orientation for both core and sheath components and possess considerable resistance to core/sheath separation. This resistance to pull-out is due to compressive and radial stresses developed during the composite coextrusion and not to bonding by epitaxial crystallization.