Measurement of Curative Diffusion Between Rubbers by Microinterferometry

Abstract

Abstract Diffusion of sulfur and MBTS across interfaces between dissimilar rubbers has been measured by microinterferometry. This technique involves the comparison of optical path length through refractive index gradients, due to diffusion, against that of a reference area. Differential diffusion coefficients are obtained showing considerable change in coefficient with curative concentration. Diffusion of sulfur between NR, SBR, and BR is quite similar to diffusion in the homo-polymer. Butyl rubber has a much lower diffusivity and limits diffusion of a curative from another rubber. The method also can be used for dissolution measurements on curatives. Microinterferometry is particularly useful in obtaining concentration and diffusion data at short distances from an interface.