ABS is a copolymer of Acrylonitrile, Butadiene, and Styrene. ABS plastics generally possess medium strength and performance and medium cost; ABS is often used as the cost and performance dividing line between standard plastics (PVC, polyolefins, polystyrene, etc.) and engineering plastics (acrylic, nylon, acetal, etc.). ABS polymers can be engineered by the manufacturer to give a range of physical properties, depending on the ratio of the monomeric constituents and the molecular level connectivity. Typically, a styrene-acrylonitrile glassy phase is toughened by an amorphous butadiene/butadiene-acrylonitrile rubber phase.
ABS is a terpolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The proportions can vary from 15 to 35% acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene. The result is a long chain of polybutadiene criss-crossed with shorter chains of poly(styrene-co-acrylonitrile). The nitrile groups from neighboring chains, being polar, attract each other and bind the chains together, making ABS stronger than pure polystyrene. The styrene gives the plastic a shiny, impervious surface.
Molding ABS at a high temperature improves the gloss and heat resistance of the product whereas the highest impact resistance and strength are obtained by molding at lower temperatures.
Because of its good balance of properties, toughness/strength/temperature resistance coupled with its ease of moulding and high quality surface finish, ABS has a very wide range of applications. These include domestic appliances, telephone handsets computer and other office equipment housings, lawn mower covers, safety helmets, luggage shells, pipes and fittings. Because of the ability to tailor grades to the property requirements of the application and the availability of electroplatable grades ABS is often found as automotive interior and exterior trim components