Nitrile rubber (NBR) is a copolymer of butadiene CH2 = CH-CH-CH2 and acrylonitrile CH2 = CH-CN (ACN), mainly using low temperature (5 ° C) emulsion polymerization. According to the propylene content and use classification, there are different grades due to Mooney viscosity and pollution. High-performance varieties such as hydrogenated nitrile, powdered nitrile, nitrile thermoplastic elastomer and special nitrile are developing rapidly.