AbstractTwo aromatic polysulfones, poly(oxy‐1,4‐phenylenesulfonyl‐1,4‐phenyleneoxy‐1,4‐phenyleneisopropylidene‐1,4‐phenylene) (I) and poly (oxy‐1,4‐phenylenesulfonyl‐1,4‐phenylene) (II), undergo crosslinking and chain scission at 30°C during γ‐irradiation, the former being predominant in vacuum and the latter in air. Both processes occurred more readily in I, which contains isopropylidene linkages. Gel measurements gaveG(crosslink) = 0.051,G(scission) = 0.012 for this polymer at 30°C in vacuum. Increased irradiation temperatures resulted in higher crosslinking and gas yields, especially above the glass transition temperature. The tensile strength, flexural strength, and modulus of I were unaffected by γ‐irradiation up to about 50 Mrad in air, but the strength decreased markedly at higher doses. The elongation at break decreased progressively with dose. For both polymers,G(gas) = 0.04 at 30°C with the main products
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