Solid-state deformation processing of crosslinked high molecular weight
polymers such as UHMWPE, for example by extrusion below the melt
transition, produces materials with a combination of high tensile
strength and high oxidative stability. The materials are especially
suitable for use as bearing components in artificial hip and other
implants. Treated bulk materials are anisotropic, with enhanced strength
oriented along the axial direction. The material is oxidatively stable
even after four weeks of accelerated aging in a pressure vessel
containing five atmospheres of oxygen (ASTM F2003). Because of its
oxidative stability, the deformation processed material is a suitable
candidate for air-permeable packaging and gas sterilization, which has
thus far been reserved for remelted crosslinked UHMWPE.