Polytetrafluoroethylene

39.04 - Polymers of vinyl chloride or of other halogenated olefins, in primary forms. 3904.10 - Poly(viny1chloride), not mixed with any other substances - Other poly(viny1 chloride) : - - Plasticised 3904.30 - Vinyl chloride-vinyl acetate copolymers 3904.40 - Other vinyl chloride copolymers 3904.50 - Vinylidene chloride polymers 3904.22 - - Polytetrafluoroethylene 3904.69 - - Other 3904.90 - Other 3904.61 This headin covers poly(viny1 chloride) (PVC), vinyl chloride copolymers, vinylidene chloride polymers, o' r0 olyrners and polymers of other halo enated olefins. For the classification of polymers (inclu ing copolymers), chemically modifie polymers and polymer blends, see the General Explanatory Note to this Chapter. d 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 co olymers of vinyl chloride are vinyl chloride-vinyl acetate copolymers which are d y used or gramophone records and flooring. P Co olymers of vinylidene chloride are used largely for packaging of food products, for up! Iolstery, fibf-es, bristles and latex coatings and in the manufacture of pipes for chemical processing equipment. lene (PTFE), one of the most important fluoro-polymers, has very in the electrical, chemical and engineering industries. Because of its high wor ng 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(viny1idene fluoride), etc.