Depression of sorption of volatile compounds into EVA film by electron beam irradiation

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Abstract
Decrease in solubility of volatile compounds (octan‐l‐ol, octanal, ethyl hexanoate, octane and d‐limonene) into a film liner was studied after electron beam irradiation up to 20 Mrad of ethylene vinyl acetate copolymer (EVA) film. The solubility coefficient decreased gradually during ageing despite no change immediately after the irradiation. In all films dosed with 5‐20 Mrad the sorption was depressed about 40% in comparison with the unirradiated one after 4 months. The behaviour was consistent with that of the decay of the radicals in the films. The enthalpy change in sorption (ΔH) was −18.0 kJ mol−1 for 5 Mrad ethylene vinyl acetate copolymer film compared with −48.1 kJ mol−1 for the unirradiated one. In a homologous series, sorption was significantly depressed with increasing carbon chain length of the volatile compound. The specific sorption depression effect was observed for low polarity compounds such as hydrocarbons, aliphatic esters and d‐limonene. The diffusion coefficient of the sorbed compounds increased about 1.6 times after 3 months when irradiated to 20 Mrad.