A generic term comprising the various copolymers of butadiene and acrylonitrile. the copolymers vary essentially in butadiene-acrylonitrile ratios, Mooey values and staining properties. They are resistant to solvents, oils, and greases and to bent and abrasion. Some trade names are Chemigum, Krynac, Nipol, Hycar, and Paracril. The Germans first produced the nitrile rubbers and called them Buna N and Perbunan.