Sorption, diffusion, and permeation of chlorinated hydrocarbon vapors through natural rubber, epoxidized natural rubber, and their blends

The study investigates the transport process of various chlorinated hydroca rbons through natural rubber (NR), epoxidized natural rubber (ENR), and the ir blends. The effect of structure and morphology of the membranes on the t ransport parameters has been investigated. Sorption coefficient is found to increase and the permeability coefficient shows the reverse trend with inc reasing epoxy content. As the mol% epoxidation increases, the polymeric net work structure becomes more compact, which leads to a decrease in the diffu sion coefficient, which ultimately results in a low permeation coefficient. The morphology of NR/ENR blends has been investigated by combining scannin g electron microscopy with permeability measurements. The permeation coeffi cient is found to be minimum for the NR/ENR 70/30 composition; a 50/50 comp osition shows the maximum. The heterogeneous morphology of 70/30 NR/ENR ble nd results in the low permeability coefficient, whereas the co-continuous n ature of the 50/50 composition accounts for the maximum permeability. Perme ability measurements provide the most useful information about the way morp hology is changing with composition of the blends and about the composition corresponding to the maximum level of co-continuity of the two phases.