Unsaturated

39.07 Polyacetals, other olyethers and e oxide resins, in primary forms; polycarbonates, alkyd resins, polya iyl esters and ot er polyesters, in primary forms. R 3907.10 - Polyacetals 3907.20 - Other polyethers 3907.30 - Epoxide resins 3907.40 - Polycarbonates 3907.50 - AUcyd resins 3907.60 - Poly(ethy1ene terephthalate) 3907.70 - Poly(1actic acid) - Other polyesters : 3907.91 - - Unsaturated 3907.99 - - Other This heading covers : fittings, etc. (2) Other polyethers. Polymers obtained from epoxides, glycols or similar materials and characterised by the presence of ether-functions in the polymer chain. They ate not to be confused with the polyvinyl ethers of heading 39.05, in which the ether-functions are substituents on the polymer chain. The most important members of this group are oly(ox ethylene) (polyethylene ycol), polyox ropylene and polyphenylene oxide b . 0 ) more correctly named po y dimethyl heny ene-oxide)). These products have a vmety of uses, PPO being use& like %e pol acetals, as engineering plastics, polyoxypropylene as an intermediate for polyurethane o m . r P YP B This heading also covers e lated (polyethylene lycol (or PEGS) polymers) derivatives of products of Chapter 29 &$-chapters I to X and eadings 29.40 and 29.42). \ Pe lated products whose non-pegylated forms are classified either in Chapter 29 (headin s 29.36 m 9.39 and 29.41) or in Cha ter 30 are excluded and in general remain classified in i e same heading as their non-pegylated oms. Y F (3) Epoxide resins. Polymers made, for example, by condensin epichlorohydrin 1-chloro-2,3-epoxypropane) with bisphenol A (4,4'-isopro ylidenefiphenol [Phenolic) resins or other compounds or by epoxi ! i sing unsaturate polymers. nOvO1* Whatever the basic these resins are characterised by the presence to be readily cross-linked at the time of use, e.g. by the an organic acid or anhydride, a boron tnfluoride complex or an organic polymer. d2 Epoxide resins range from low viscosity liquids to high melting solids; they are used as surface-coatings, as adhesives, as moulding or casting resins, etc. Epoxidised animal or vegetable oils are classified in heading 15.18. (4) Polycarbonates. Pol ers obtained, for example, b condensing bisphenol A with phosgene (carbonyl c loride) or diphenyl carbonate an characterised b the resence of carbonic ester-functions in the polymer chain. These have a num er o industrial applications, particularly in moulded articles and as glazing. K" J' z P (5) Pol esters. These polymers are characterised by in t)he polymer chain and are obtained, for alcohol and a polycarboxylic acid. They are heading 39.05 and polyacrylic esters of headin 39.06, in which the ester groups are substituents on the polymer chain. Polyesters inclu e : a of polyfunctional alcohols and one of which at least must be partly or wholly other substances such as fatty acids or animal acids or alcohols, rosin. They do not include oil-free resins are used mainly as coatings and in high grade in viscous form or solution. a a (b) Polyallyl esters. A s ecial class of unsaturated polyesters (for the term " unsaturated " see Item (e below) erived from esters of ally1 alcohol with dibasic acids, for exam le, diallyl pht alate. They are used as laminat~ngadhesives, coatings, varnishes a n ! in applications requiring microwave transparency. a (c) Poly(ethy1ene tere hthalate) (PET).Polymer general1 formed by the esterification of tere hthalic aci with ethylene glycol or obtained om the reaction of dimeth 1 ter ht alate with ethylene glycol. Apart fiom its very important use in textiles, it fin s ap$cation, for example, in packaging films, recording tapes, soft-drink bottles. R X i' (d) Poly(lactic acid), also known as polylactide. It is usually produced fiom lactic acid obtained synthetically or by fermentation (this method uses raw materials consisting predominantly of hexoses or compounds which can be easily split into hexoses, e.g., sugars, molasses, su ar beet 'uice, sulphite liquors, whey or starches). The lactic acid is converted to a cyc ic lacti e dimer, the ring structure of which is o ened during the final polymerisation step. Its applications include textile fibres, pac ging materials and materials for medical use. 1. -d R, (e) Other polyesters. These may be unsaturated or saturated. Unsaturated polyesters are those which possess sufficient ethylenic unsaturation that they can readily be (or already have been) cross-linked with monomers containing ethylenic unsaturation to form thermosetting products. Unsaturated polyesters include olyallyl esters (see Item @) above) and other olyesters (including oil-fiee alkyds) lased on an unsaturated acid, for example, ma eic or frrmaric acid. These products, which are usually in the form of liquid prepolyrners, are mainly used for producing glass fibre reinforced laminates and cast transparent thermosetting products. f Saturated polyesters include polymers based on terephthalic acid, for example, oly(buty1ene terephthalate), and saturated oil-free alkyd resins. They are largely used !or textile fibres and films. For the classification of olymers (including copolymers), chemically modified polymers and polymer blen s, see the General Explanatory Note to this Chapter. d'