Diffusion of liquids in crosslinked rubbers. Part 1

Abstract

The diffusion of various liquids in natural rubber vulcanizates has been studied by following the kinetics of the mass uptake of a sheet of rubber while immersed in the liquid. An anomaly in the mass uptake-time relation is due to the stresses set up in the sheet during swelling and to their variation as the swelling proceeds. This anomaly has been eliminated by using samples constrained laterally, by bonding to metal backing plates, which maintains the boundary conditions constant during the swelling. At the liquid concentrations used, the diffusion coefficient depends mainly on the liquid viscosity rather than the compatability of the rubber and the liquid. Neither the amount of carbon black filler not the degree of crosslinking of the rubber has a significant effect on the diffusion coefficient measured at relatively high liquid concentrations.