HYDROLYTIC AGING OF POLYCARBONATE .2. HYDROLYSIS KINETICS, EFFECT OF STATIC STRESSES

Plaques of bisphenol A polycarbonate (PC) were exposed to a water-satu rated atmosphere at temperatures ranging from 40 to 90-degrees-C for u p to 7 months. Certain samples were exposed under tensile load at 60 a nd 90-degrees-C, 100% RH with stresses ranging from 3.7 to 8.7 MPa. Th e PC molecular weight was determined by steric exclusion chromatograph y, and the kinetic parameters for hydrolytic chain scission were deter mined. It appears clearly that in the presence of tensile stresses, th e hydrolysis rate is increased (at both temperatures under study) by a factor of about 10. The stress effect cannot be represented by the Ey ring-Zhurkov relationship because the activation volume appears as an increasing function of the temperature and a decreasing function of ti me. Some possible causes of the observed stress effects are discussed (C) 1995 John Wiley & Sons, Inc.