HEADING 39.11 - PETROLEUM RESINS COUMARONE-INDENE RESINS POLYTERPENES POLYSULPHIDES POLYSULPHONES AND OTHER PRODUCTS SPECIFIED IN NOTE 3 TO THIS CHAPTER NOT ELSEWHERE SPECIFIED OR INCLUDED IN PRIMARY FORMS.

50 COMMODITIES

This heading covers the following products :

(1) Petroleum resins coumarone indene or coumarone-indene resins and polyterpenes constitute a group of resins not highly polymerised made by polymerising more or less impure fractions obtained respectively from deeply cracked petroleum distillates from coal tar or from turpentine or other sources of terpenes. They are used in adhesives and coatings and are often incorporated as softeners in rubber or plastics for example for use in floor tiles.

(2) Polysulphides are polymers characterised by the presence of monosulphide linkages in the polymer chain for example polyphenylene sulphide. In polysulphides each sulphur atom is bound on both sides by carbon atoms as opposed to the thioplasts of CHAPTER40 which contain sulphur-sulphur linkages.

Polysulphides are used in coatings and in moulded articles for example aircraft and automobile parts pump impellers.

(3) Polysulphones are polymers characterised by the presence of sulphone linkages in the polymer chain for example the product obtained by reacting the sodium salt of bisphenol A (4 4 with bis(4-chlorophenyl) sulphone. They are used in electrical parts domestic appliances etc.

(4) Other products specified in Note 3 to the Chapter include polyxylene resins poly (1 4 polyvinyl ketones polyethyleneimines and polyimides.

For the classification of polymers (including copolymers) chemically modified polymers and polymer blends see the General Explanatory Note to this Chapter.