Aspects of the Chemistry of Poly (Ethylene Terephthalate). IV. Hydrolysis of Poly(Ethylene Terephthalate) in the Melt Phase

The effect of water vapor pressure on the molecular weight of molten poly (ethylene terephthalate) has been followed by measurement of the changes which occur in the intrinsic viscosity and the end-group concentrations upon hydrolysis. It was found that phosphoric acid is highly effective as a stabilizer; the hydrolysis rate constant (Kh) decreasing from 7.6 × 10−7 mol−1s−1 for nonstabilized to 2.5 × 10−7 mol−1s−1 for the stabilized polyester at 290°C and water vapor pressure of 20 mmHg.