CARBON-BLACK ELASTOMER INTERACTION

A number of different techniques were applied to measure carbon-black-surface reactivity and the level of black-polymer interaction in four different elastomer systems (SBR, IIR, NR, and NBR) representing differences in unsaturation, crystallinity and polarity. Known within-grade surface activity variations were based on partial graphitization of an N121-type carbon black. The surface activity of different black grades was studied as a function of variations in both surface area and DBPA. Direct measurements of carbon-black-surface reactivity were based on hydrogen analysis, SIMS, IGC, and moisture adsorption. In-rubber measurements included bound rubber, SIMS of cut surfaces, and an interaction parameter, σ/η, which is derived from the slope (σ) of the stress-strain curve at low elongations, and (η), the ratio of dynamic modulus (E′) at 1% and 25% DSA. Results and trends are described in this paper.