Temperature effects on the radiation degradation of poly(isobutene) and poly(alpha-methylstyrene)

The effect of temperature on the radiation chemistry of poly(isobutene) and poly(a-methyl styrene) has been studied over the temperature range at which the polymers begin to degrade thermally. The radical intermediates have been Investigated using ESR spectroscopy and their chemical yields and reactivities have been examined using thermal annealing techniques. The low molecular weight products of radiolysis at 300 K have been investigated and their yields measured. Hydrogen was the major low molecular weight product of radiolysis together with monomer, but no significant depropagation of the chain radical was found to occur at 300 K. Molecular weight studies at 300 K showed that the polymers undergo predominantly chain scission at room temperature, and the yields of scission and crosslinking have been determined at this temperature. At higher temperatures both polymers were found to undergo radiation induced depolymerization, and in these temperature regions, the values of G(S) and G(-M) have been determined.