Expansible

39.03 - Polymers of styrene, in primary forms. - Polystyrene : 3903.11 - - Expansible 3903.19 - - Other 3903.20 - Styrene-acrylonitrile (SAN) copolymers - Acrylonitrile-butadiene-styrene(ABS) copolymers 3903.90 - Other 3903.30 This heading covers polystyrene and co olymers of styrene. The most important copolymers of (s& copolymers, acrylonitrrle-butadiene-styrene (ABS styrene are s ene-ac lon~tr~le co olymers an styrene- utadiene copolymers. Most of the styrene-butadiene copolymers wit su stantial amounts of butadiene comply with the requirements of Note 4 to Chapter 40 and are therefore classified in Chapter 40 as synthetic rubber. For the classification of polymers (including copolymers), chemically modified polymers and polymer blends, see the General Explanatory Note to this Chapter. E' I Unexpanded polystyrene is a colourless, transparent, thermoplastic material which finds extensive use in the electrical and radio industries. It also has packagin applications, for example, in the packa ' g of foodstuffs and cosmetics. It is also used zn t e manufacture of toys, clock cabinets an gramophone records. % r Ex anded (cellular) polystyrene contains gases from the expanding process and has a low buk-density. It is extensively used as a thermal insulent for refii erator doors, air-conditioner housings, cold storage facilities, fieezer display cabinets, and in t e construction industry. It is also used in disposable packaging and in food serving articles. b Certain chemically modified copolymers of styrene are ion-exchangers (heading 39.14). Styrene-acrylonitrile (SAN) cop01 ers, which have good mouldability and chemical resistance, are used or making cups, refigerator arts oil-filter bowls and certain kitchen. equipment. $-sj copolymers, which have hi shock and weather resistance, are used in the manufacture o parts and accessories of bodies or motor vehicles, of refrigerator doors, of telephones, of bottles, of shoe heels, of cases for machines, of water pipes, of building panels, of vessels, etc. r" P