The determination of randomness in copolyesters by high resolution nuclear magnetic resonance

Abstract High‐resolution nuclear magnetic resonance (NMR) spectra of several kinds of polyesters were measured. Proton signals due to heterolinkages could be observed in some copolyesters, and the average sequence length and the degree of randomness in the copolyester were calculated from the intensities of their signals. A process in the transesterification reaction between two kinds of homopolyester was pursued with the NMR spectra. Random copolyester is formed by the ordinary molten‐state copolycondensation and also during the transesterification reaction between two kinds of homopolyester.