Molecular transport of methyl- and methoxy-substituted benzenes into bromobutyl rubber, chlorosulfonated polyethylene and epichlorohydrin membranes

Abstract

The diffusion and sorption of monocyclic aromatics such as benzene, toluene, p-xylene, 1,3,5-trimethylbenzene and methoxybenzene into bromobutyl rubber, chlorosulfonated polyethylene and epichlorohydrin membranes was investigated over the temperature range 25–60°C using a sorption gravimetric technique. The anomalous behaviour of some polymer-solvent systems was attributed to the greater relaxation of polymer chain segments than the movement of solvent molecules within the polymer matrices. Transport results were analysed using the Fickian model. A decrease in transport coefficients with an increase in diffusant size was observed. Arrhenius activation parameters were calculated from the temperature dependence of transport coefficients. Experimental and computed results were used to study polymer-solvent interactions in terms of polymer structures and the nature of solvent molecules.