Ionizing radiation is a growing means of sterilizing medical devices, and as a means of food preservation. These uses require packaging materials which maintain useful properties through a sterilization cycle. In the study presented here, films of "Surlyn" 1601 sodium ionomer and "Surlyn" 1652 zinc ionomer were exposed to sterilizing doses of gamma and electron-beam radiation, and the effects on mechanical and heat seal properties determined over a one-year period. The results showed that ionomers retain their mechanical properties following radiation. The strength of heat seals is also maintained. A special zinc ionomer, "Surlyn" AD-8273, gives both interfacial peelable and fusion seals depending on sealing temperature. Following radiation exposure, heat seal strength in the peelable range increased in a predictable fashion.

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