copely(p -hydroxybenzoate /bisphenol A terephthalate). was characterized by high resolution nuclear magnetic resonance(NMR) spectroscopy (including twodimensional techique
2D NMR). It was found that the 13C-NMR spectra of carbonyl group in the copolyester chain were not so simple as in the monomeric aromatic ester and they gave the useful information of the chain sequences. There are good relationships between the carboxyl group resonance peaks and the triad of the monomer residues.