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Acrylonitrile butadiene styrene (ABS) (chemical formula (C8H8)x· (C4H6)y·(C3H3N)z) is a common thermoplastic. Its glass transition temperature (ABS is amorphous and therefore has no true melting point) is approximately **5 °C (**1 °F).
It is a terpolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The proportions can vary from *5 to *5% acrylonitrile, 5 to *0% butadiene and *0 to *0% 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. The butadiene, a rubbery substance, provides resilience even at low temperatures. For the majority of applications, ABS can be used between **0 and *0 °C (*4 and **6 °F) as its mechanical properties vary with temperature. The properties are created by rubber toughening, where fine particles of elastomer are distributed throughout the rigid matrix.
Production of 1 kg of ABS requires the equivalent of about 2 kg of petroleum for raw materials and energy. It can also be recycled.
ABS plastic is damaged by sunlight. This caused one of the most widespread and expensive automobile recalls in US history.

ABS's light weight and ability to be injection molded and extruded make it useful in manufacturing products such as drain-waste-vent (DWV) pipe systems, musical instruments (recorders, plastic clarinets, and piano movements), golf club heads (due to its good shock absorbance), automotive trim components, automotive bumper bars, medical devices for blood access, enclosures for electrical and electronic assemblies, protective headgear, whitewater canoes, buffer edging for furniture and joinery panels, luggage and protective carrying cases, small kitchen appliances, and toys, including Lego bricks.[8]
ABS plastic ground down to an average diameter of less than 1 micrometer is used as the colorant in some tattoo inks.[citation needed] Tattoo inks that use ABS are extremely vivid. This vividness is the most obvious indicator that the ink contains ABS[citation needed], as tattoo inks rarely[9] list their ingredients.
ABS is also commonly used in rapid prototyping extrusion-based 3D printers. Its glass transition temperature makes it a material of choice for rapid prototyping — relatively high as to reduce unwanted deformation at slightly elevated temperatures but low enough to be safely attainable with standard extrusion setups.