Free Radicals in Irradiated Nylon

Gamma irradiation of undrawn filaments of nylon 6 produces several different free radicals whose concentration, ESR pattern, and lifetimes are affected by irradiation temperature, dose, storage conditions, and crystallinity. A five-peak short-lived species, measured at liquid-nitrogen temperature, predominates at low doses, low irradiation temperatures, and is believed to be a free radical associated with the carbon α to the amide nitrogen. A broad singlet is found at higher doses and is believed to be a radical in a conjugated system which includes the amide group. The experimental results are explained in terms of a free radical which is capable of migrating by a hydrogen-atom transfer process.