Curative Diffusion between Dissimilar Elastomers and its Influence on Adhesion

Abstract

Abstract The diffusion of common curatives, such as sulfur, TMTD, MBTS, and DOTG, at vulcanizing temperatures between butyl, chlorobutyl, or EPDM and natural rubber, SBR, BR, or neoprene has been studied by light microscopy and attentuated total reflectance infrared. Diffusion occurs with all these curatives. Curative solubility in rubber, which affects diffusion, has been measured at various temperatures. Prom this, distribution coefficients have been calculated by considering the system as a liquid-liquid extraction. These coefficients range between 0.7 and 10. Diffusion coefficients have been obtained, and the energy of activation for diffusion has been calculated. The effect of diffusion upon adhesion between rubbers is also discussed.