Poly(ethylene terephthalate): A solid state condensation process, 2. Copolymerization

Copolyesters of poly(ethylene terephthalate) containing 0,95 to 14,2 mole‐% di(oxyethylene)oxy units are prepared in a solid state condensation process. A low molecular weight prepolymer with reactive end groups is annealed at temperatures between 235 and 250°C. Samples with molecular weights from 2 000 to 26 000 are obtained. The melting behaviour of the copolyesters is determined by the crystallinity of the precondensate, the counit content, and the degree of polymerization.