Effects of oxidation of carbon black surface on the properties of carbon black–natural rubber systems

Abstract

Proton spin-spin relaxation time (T2) was measured by the pulsed NMR technique for bound rubbers in composites prepared from natural rubber and carbon black at different acid group concentrations. The bound rubber consisted of loosely and tightly bound rubbers. By incorporation of the oxidized carbon black with a high concentration of acid groups into natural rubber, the content of the total bound rubber in the composite increased, and the segmental mobility of the loosely and tightly bound rubber constituting the bound rubber was enhanced. The increase in the segmental mobility of the bound rubber and its content resulted from the formation of the bound rubber with fairly long loops on the oxidized carbon black. The change in reactivity of the carbon black brought about nitric acid treatment is also discussed in connection with the results mentioned above. © 1983 The Society of Polymer Science, Japan.