The Chemistry of Carbon Black in Rubber Reinforcement

Abstract

Abstract 1. The removal of chemisorbed oxygen from channel black and furnace black, without alteration of the underlying carbon surface, results in only minor effects in reinforcement potential regardless of the curative system employed, whether polar or free radical. 2. When the underlying carbon surface is changed by heat treatment to a state of lower energy, a significant decrease in the reinforcing ability of the carbon black results. 3. Different types of oxygen functional groups added to the carbon surface produce similar effects upon rubber properties. 4. These effects are limited to retardation of cure rate in sulfur curing systems. Only small effects of any kind are produced in the natural rubber-peroxide system. 5. The net conclusion to be drawn is that combined oxygen on the carbon surface plays a relatively minor role in the chemical effect of carbon black upon reinforcement; the nature of the carbon surface itself is of primary importance.