SYNOPSISPlaques of bisphenol A polycarbonate (PC) were exposed to a water-saturated atmosphere at temperatures ranging from 40 to 90°C for up to 7 months. Certain samples were exposed under tensile load a t 60 and 9O"C, 100% RH with stresses ranging from 3.7 to 8.7 MPa. The PC molecular weight was determined by steric exclusion chromatography, and the kinetic parameters for hydrolytic chain scission were determined. It appears clearly that in the presence of tensile stresses, the hydrolysis rate is increased (at both temperatures under study) by a factor of about 10. The stress effect cannot be represented by the EyringZhurkov relationship because the activation volume appears as an increasing function of the temperature and a decreasing function of time. Some possible causes of the observed stress effects are discussed 0 1995 John Wiley & Sons, Inc. I NTRO DUCT10 NThere is relatively abundant literature data on the hydrolytic aging of polycarbonate ( PC ) at temperatures ranging between 40 and 100°C.1-4 The mechanism can be described as follows:

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