AbstractThe diffusion (D) and permeability (P) coefficients for14CO2in polystyrene films which had been irradiated by short‐wave ultraviolet (253.7 nm) radiation under vacuum and in oxygen were determined in the temperature range of 20° to 55°C. BothDandPdecreased with increasing exposure, the vacuum‐irradiated sample showing significantly greater decreases, presumably on account of a larger extent of crosslinking which was possible in the absence of oxidation. A good correlation was observed between crosslinking and decreasingPandDvalues. The solubility coefficients for all irradiated samples increase with increasing dose. Activation energies for diffusion increase with increasing irradiation, particularly for the vacuum‐irradiated samples. Reductions inPandDvalues are interpreted in terms of free‐volume decreases due to crosslinking and other modifications, while the increasing activation energies are attributed to the increasing energy requirements for creation of free volume in modified
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