Propagation/depropagation equilibrium and structural factors in the radiation degradation of poly(olefin sulfone)s

Abstract

AbstractThe principal volatile products observed after γ irradiation of nine different poly(olefin sulfone)s in the solid state were the two comonomers, i.e., the respective olefin and sulfur dioxide. An exponential increase in yield, G(volatile products), with increasing irradiation temperature, Tirr, was observed for each copolymer through the ceiling temperature, Tc, for the corresponding propagation/depropagation equilibrium. Thus the G value increased by ca. 3 orders of magnitude from Tirr = 0.7 Tc to Tirr = 1.3 Tc for all of the poly(olefin sulfone)s. Depropagation sensitivity was considered to be best measured by G(SO2) since radiation induced, cationic homopolymerization of the product olefin occurred to a variable extent. Five of the poly(olefin sulfone)s had similar rates of depropagation at their respective Tc's but the polysulfones of 1‐hexene, cyclohexene and 2‐butene showed anomalously high depropagation rates. This may be related to greater steric hinderance to segmental chain mobility in the polysulfones of the 1,2 disubstituted olefins. Poly(1‐hexene sulfone) appears to be anomalous, as in other respects.