Properties of Closed-Cell Butyl and Nitrile Materials

Abstract

Closed-cell materials were prepared from two types of thermosetting elastomers, carboxyacrylonitrile-butadiene copolymer nitrilee) and isobutylene-isoprene co-polymer (butyl), containing carbon black reinforcing filler. A chemical blowing agent, pp'-oxybis(benzene-sulfonyl hydrazide), which decomposes rapidly between 1530 and 160°C with a release of nitrogen, and a low-pressure compression molding process were used in the fabrication. The resulting cellular materials had densities between 0.66 and 0.84 g/cc. The curing characteristics of the formulations were studied with an oscillating disk rheometer. Viscoelastic properties were gathered with a dynamic mechanical analyzer over a -90° to 80°C temperature interval. Other properties, such as an abrasion resistance and compression set, were also determined. The data indicate that the cellular nitrile materials should excel in applications where wear-resistance is needed and butyl materials in applications where good flexibility and energy dissipation at low temperatures are desired.