Permeation of Chlorinated Hydrocarbon Vapours through Poly(Ethylene-Co-Vinyl Acetate) Membranes
The permeation of chlorinated hydrocarbon vapours through uncrosslinked and crosslinked poly(ethylene-co-vinyl acetate) (EVA) membranes has been analysed. EVA was crosslinked by dicumyl peroxide and benzoyl peroxide. The uncrosslinked sample showed a lower permeation coefficient due to its crystalline nature. The crystalline nature was supported by X-ray diffraction analysis. The differences in the permeation behaviour of the two crosslinked samples were correlated with crosslink density. Crosslink density was calculated using the equilibrium sorption method. The permeation behaviour is also supported by differential scanning calorimetry. The influence of the crosslink density and the size of penetrants on permeation was analysed. The effect of free volume on the gas barrier properties was investigated by positron annihilation lifetime spectroscopy (PALS).