Fourteen kinds of polyesters were synthesized, which is to study the characteristics of terminal hydroxyl alpha-H of polyester in H-1 nuclear magnetic resonance (NMR) spectra. Utilizing the results that the peak of terminal hydroxyl alpha-H of polyester does not interfere by other peaks of polyester, a new simple and sensitive method to determine the hydroxyl value of polyester by H-1 NMR was established. In this method, a modified H-1 NMR pulse sequence and improved parameters were adopted, and styrene was added as the internal standard. The investigated results show that the relative error of theoretica values and measured valuew in this method is lower than 1% and the precision is +/-0.2. This method is characterized not only by simplicity and rapidity but also by high precision.
