IH NMR RELAXATION STUDIES OF CURED NATURAL RUBBERS WITH DIFFERENT CARBON BLACK FILLERS

H NMR relaxation data provide insight into the effects of carbon black fillers on the structure of polymer networks in products based on natural rubber so that accepted ideas concerning the interaction between elastomeric networks and active filling materials arc confirmed. A new ʹH NMR relaxation experiment allows the direct investigation of dangling chains within the polymeric network. In samples containing carbon black a motional anisotropy is observed for these chain ends, while dangling chains in samples without carbon black fillers show isotropic rotadonal motions. The parameter qʹ, quantifying the motional anisotropy, is suggested to he a measure of the physico-chemical inleractions between elastomer and filler.