PREPARATION OF POLYESTER SAMPLES FOR COMPOSITION ANALYSIS

In commonly used methods for the analysis of polyesters, the polymer is hydrolyzed to its monomeric components, which are then determined by chromatography. The time it takes to hydrolyze the polyester is often considerably longer than the time spent on subsequent steps of the analysis. Furthermore, highly crystalline and liquid-crystalline polyesters can be nearly inert in the reagents used to hydrolyze other polyesters. It would, therefore, be desirable to improve the rate at which polyesters could be prepared for analysis. It was found that a mixture of hydroxide, an alcohol, and certain polar aprotic solvents will hydrolyze polyesters at rates much faster than any reagent previously described. Even highly crystalline polyesters can be quantitatively hydrolyzed to their corresponding monomers in a few minutes with this reagent. Three methods for the analysis of polyesters are described that use this reagent for the rapid preparation of the polymer sample. Methods for the determination of acids, diethylene glycol in poly(ethylene terephthalate), and glycols and diacids by NMR are described. We conclude that this new reagent provides much faster rates for polyester hydrolysis than those previously disclosed. This reagent can be used to prepare samples for analyses by chromatography or NMR.