Abstract

Nitrile rubbers are copolymers of 1,3-butadiene and acrylonitrile that have been produced by emulsion polymerization for about 50 years. They carry the ASTM designation NBR. A wide variety of products are available from a number of worldwide suppliers. The primary uses of NBR are in seals, O-rings, hose, and gaskets, where resistance to hydrocarbon fluids like gasoline and oil is required. A second important use is in the modification of plastic materials to provide impact resistance and flexibility. This article covers the properties and uses of NBR and its hydrogenated derivative HNBR. Manufacturing processes, world usage and capacity, and toxicological considerations are also described.