Molecular weight distributions in radiation‐induced polymerization. VI. γ‐ray‐induced polymerization of “dry” styrene in the solid state

Abstract

AbstractThe γ‐ray‐initiated polymerization of styrene in the solid state has been studied over the temperature range −35°C to −55°C for samples exhaustively purified and dried to remove residual water (“dry” samples). Comparison with kinetic results previously reported for dry samples in the liquid state indicates a sharp decrease in the rate of polymerization resulting from the liquid to solid state transition. The molecular weight distributions for in‐source polymerization at −35°C and −40°C are bimodal in nature, and the appearance of a third peak is noticeable at −47°C and −55°C. In the case of postpolymerization at −35°C the molecular weight distribution is bimodal as in the case of in‐source samples. In the former case, however, the high molecular weight peak is predominant whereas the low molecular weight peak predominates in the latter. These results have been tentatively attributed to the postulated coexistence of two distinct propagating species which are radical and cationic in nature.