Post 284 – by Gautam Shah
ABS (Acrylonitrile-butadiene-styrene) has been described as wonder or Industrial plastic. Styrene Acrylonitrile copolymers were available since 1940’s, but introduction of a Butadiene as a third component in the 1950s created a range of ABS plastics.
ABS polymers are not affected by water, salts, inorganic acids, food acids and alkalis, alcohols and animal, vegetable and mineral oils. ABS plastics are soluble in ketone, swell or soften in some chlorinated hydrocarbons, esters, aromatics and aldehydes.
ABS can be moulded, extruded, vacuum-formed, blow moulded, rotational moulded and chrome plated. Moulding at a high temperature improves the gloss and heat resistance; however, high impact resistance and strength, are available by moulding at low temperature. ABS plastics are used largely for mechanical purposes, they also have remarkable electrical properties that are fairly constant over a wide range of frequencies and unaffected by temperature and atmospheric humidity. ABS is damaged by sunlight, causing a widespread and expensive recall of automobiles in US history.
ABS is used for brief cases, suit cases, printer bodies, remote control bodies, television bodies, hair dryers, textile bobbins, toys including Lego and Kre-O bricks, plated car linings and trims, bumpers, bars, furniture, protective headgear, hardware, water-taps, sanitary ware, golf-club heads. ABS raw material colour is ivory to white, but can be pigmented. ABS plastic ground down to a dia. of less than one micrometer is used as the vivid colourant in some tattoo inks.
Its glass transition temperature is 105 °C. ABS. It is amorphous and therefore has no true melting point. ABS can be used between -20 and 80 °C, though its mechanical properties vary with temperature. ABS plastics are self-extinguishing, but flammable at high temperatures. It melts, then boils, when its vapours may burst into flames. On burning ABS does not produce any organic pollutants except carbon monoxide and hydrogen cyanide.
ABS is a Terpolymer (three-way polymer) made by polymerizing styrene and acrylonitrile in the presence of poly-butadiene. It is formed of a long chain of poly-butadiene crossed with shorter chains of poly-styrene-co-acrylonitrile, but in varying proportions (from 15-35% acrylonitrile, 5-30% butadiene and 40-60% styrene), to achieve quality variants. The Acrylonitrile imparts chemical resistance and surface hardness, Butadiene contributes the impact strength and over all toughness, and Styrene helps in processing. ABS combines the strength and rigidity of acrylonitrile and styrene polymers with the toughness of poly-butadiene rubber.