The role of crosslinking and crystallisation on the transport characteristics of ethylene–propylene rubber membranes

The transport characteristics of ethylene–propylene rubber (EPR) membranes have been examined using four aromatic hydrocarbons as probe molecules. The EPR was crosslinked by different percentage of dicumyl peroxide (DCP). Solvent uptake by EPR membranes has been found to increase with increase in the crosslinker dosage, unlike many other rubbers, up to a threshold level which is followed by a decrease at higher crosslinker content. This has been explained in terms of the differences in the degrees of crystallinity and crosslinking. The mechanism of transport has been found to deviate from the regular Fickian trend observed with conventional rubbers. The influence of penetrant size and temperature on the transport process has also been examined. A sorption–desorption–resorption–redesorption technique has been utilised to examine the structural changes during the transport process.