SORPTION OF VOLATILE COMPOUNDS INTO ELECTRON-BEAM IRRADIATED EVA FILM IN THE VAPOR-PHASE

In order to investigate the sorption of volatile compounds by electron beam irradiated ethylene/vinyl acetate copolymer (EVA) films, permeation measurements in the vapour phase were carried out. The diffusion coefficients of octane, ethyl hexanoate, octanal, octan-1-ol and d-limonene increased with an increase in the irradiation dose. The sorption of all volatile compounds in this study was depressed in electron beam irradiated film; the decreases in solubility coefficients for 20 Mrad EVA film were 15% for octane and ethyl hexanoate, 45% for octan-1-ol and octanal, and 50% for d-limonene. The enthalpy change in sorption (DELTA-H) of ethyl hexanoate was -13.4 kJ mol-1 for 50 g kg-1 EVA film at a dose of 20 Mrad compared with -27.6 kJ mol-1 for the unirradiated one. In a homologous series of aliphatic alcohols, sorption was significantly depressed with increasing carbon chain length. Judging from both heat-seal strength and sorption behaviours, the most appropriate irradiation dose for the practical usage of irradiated EVA film was less than 15, 10 and 5 Mrad for 50, 95 and 150 g kg-1 EVA film, respectively.