Combined environment aging effects: Radiation‐thermal degradation of polyvinylchloride and polyethylene

Abstract Results are presented for a case of polymer aging in which powerful synergisms are found between radiation and temperature. This effect was observed with formulations of polyvinylchloride and polyethylene and occurred in simultaneous and Sequential radiation‐thermal experiments. Dose rate dependencies, which appear to be mechanistically related to the synergism, were also found. The evidence indicates that these aging effects are mediated by a thermally induced breakdown of peroxides initially formed by the radiation. Similar effects could be important to material degradation in a variety of other types of combined‐stress environment. A new technique, which uses PH 3 treatment of intact polymer specimens to test for the importance of peroxide is the pathway that leads to changes in macroscopic tensile properties, is described.