Craze Yielding of Polycarbonate in N2, Ar, and O2 at Low Pressures and Temperatures.

摘要

The tensile stress-strain behavior of PC was measured in mixtures of He, which is inert, and each of the following crazing agents: N2, Ar, and O2 at partial pressures of 0-1 atm and in the temperature range above 77 K. The yield point for crazing depends on temperature, pressure, and the shear yield point according to the following equation: sigma sub c/sigma sub s = (P pxp to the Q/RT power /P*) to the -1/12th power, where Q and P* depend on the gas. The values of Q are approximately the same as those for the adsorption and absorption energies as determined by theories and experiments. The maximum sensitivity of the craze yield point to the partial pressure of the crazing gas occurs at the lowest pressure for crazing. In the case of N2, a 1% change in the partial pressure can produce about a 0.45-ksi change in the yield point.