Two step gamma irradiation of polymeric bioimplant

摘要

Wear resistance and oxidation resistance of a bioimplantable polymeric part is improved by packaging a bulk or unfinished polymeric object within gas impermeable package or container substantially free of oxygen, irradiating the packaged object with penetrating radiation to an extent sufficient to initiate or effect a desired substantial level of cross-linking within the polymer, and heating the package object to a point above the polymer melt temperature effective to stabilize the material against subsequent oxidative change. The stabilized material or semi-finished parts are then machined or otherwise formed into finished parts, repackaged and sterilized. Sterilization may be effected by re-packaging in vacuum foil and irradiating with an additional dose of gamma radiation. The procedure achieves very high levels of cross linking while limiting the radiation damage that is generally associated with high dose radiation, reducing susceptibility to aging or chemical degradation and avoiding the risks involved in post-treatments with reactive materials. IMAGE