DEGRADATION OF POLYMERIC BIOMATERIALS

Environmental and processing factors affecting the biostability of med ical devices made from traditionally ''stable'' polymers, such as isot actic polypropylene (PP) and ultrahigh molecular weight polyethylene ( UHMW-PE), were analyzed and their undesirable degradation was related to performance of typical medical devices. Among the critical phenomen a determining the biological performance of UHMW-PE and PP devices are oxidation during melt-processing and the propensity of the polymer ch ains to radiolyse and radio-oxidize. Polyesters and their biomedical d evices, which can be designed to degrade predictably, are addressed wi th some focus on the less obvious determinants of performance.