Influence of microstructure in nitrile polymer on curing characteristics and mechanical properties of carbon black-filled rubber composite for seal applications

Abstract

Acrylonitrile butadiene rubber (NBR) is widely used in seal applications due to its excellent oil resistance. In this article, carbon black-filled NBR composites, which differed in their acrylonitrile (ACN) and butadiene content ratios, were prepared and their curing characteristics and mechanical properties were investigated. Curing characteristics were investigated by measuring chemical kinetics and onset temperature of cross-linking reaction. Cross-linking density was measured by the volume swelling test. Mechanical properties, oil resistance, and compression set (CS) tests were also conducted. From these results, it was found that the microstructure in NBR polymer is closely connected to the curing characteristics and mechanical properties of the composite. On increasing the ACN content, Shore A hardness, tensile strength at break, elongation at break, oil resistance, and CS were raised, while, on the other hand cross-linking density, kinetics of cross-linking reaction, and bound rubber content were decreased.