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Heading 3904 : Polymers of vinyl chloride or of other halogenated olefins, in primary forms.
This heading covers poly(vinyl chloride) (PVC), vinyl chloride copolymers, vinylidene chloride polymers, fluoropolymers and polymers of other halogenated olefins. For the classification of polymers (including copolymers), chemically modified polymers and polymer blends, see the General Explanatory Note to this Chapter.
PVC is a rigid colourless material with limited heat stability and with a tendency to adhere to metallic surfaces when heated. For these and other reasons, it is often necessary to add stabilisers, plasticisers, extenders, fillers, etc. to make useful plastics. In flexible sheet form PVC is used widely as a waterproof material for curtains, aprons, raincoats, etc., and as high grade imitation leather for upholstery and interior decoration in all types of passenger transportation. Rigid PVC sheets find application in the fabrication of covers, ducts, tank linings and many other items of chemical plant equipment. PVC floor tiles are also common.
The most important copolymers of vinyl chloride are vinyl chloride-vinyl acetate copolymers which are mainly used for gramophone records and flooring.
Copolymers of vinylidene chloride are used largely for packaging of food products, for upholstery, fibres, bristles and latex coatings and in the manufacture of pipes for chemical processing equipment.
Polytetrafluoroethylene (PTFE), one of the most important fluoro-polymers, has very wide-ranging applications in the electrical, chemical and engineering industries. Because of its high working temperature it is an excellent insulating material and due to its resistance to chemicals it is almost indestructible.
Other fluoro-polymers include polymers of chlorotrifluoroethylene, poly(vinylidene fluoride), etc.
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