DOSE EFFECTS IN THE RADIATION-INDUCED ELECTRICAL-CONDUCTIVITY OF POLYMERS

Four polymers (polystyrene, polyethylene terephthalate, high-pressure polyethylene, and polytetrafluoroethylene [PTFE]) are used as examples to study how annealing effects at room and elevated temperatures in a ir and in a vacuum restore the radiation-induced electrical conductivi ty during continuous irradiation to absorbed doses on the order of 5.1 0(4) Gy (the radiation-induced electrical conductivity is reduced by a factor of 2-8 at the end of irradiation). It is shown that recovery i n polystyrene and polyethylene terephthalate is significant (up to 70% ), while further degradation of the radiation-induced electrical condu ctivity parameters dominates in high-pressure polyethylene and PTFE fo r annealing in air. The medium (vacuum or air) is observed to have a s trong effect on annealing polystyrene. In order to explain the observe d behavior, we apply concepts of radiation oxidation of high-pressure polyethylene and PTFE. For polystyrene we use a chain process with deg enerate chain branching and catalytic recombination of the macroradica ls.