ABS resin is a copolymer primarily composed of styrene (SM), acrylonitrile (AN), and butadiene (BD). ABS has very good mechanical properties, dimensional stability, processing ability, chemical resistance, and a high-quality appearance. These advantages make ABS resin an exnt engineering plastic.
 A, B, S represent acrylonitrile, butadiene and styrene, which give strength (A), flexibility (B), and hardness (S). Typically this plastic has a composition: 60% (w/w) nylethene (styrene), 25% propenonitrile (acrylonitrile), 15% buta-1,3-diene. The initiator used is often potassium peroxydisulfate, K2S2O8.