A variable radius of curvature strain-bending apparatus was used to investigate the kinetics of surface craze growth in polycarbonate exposed to three different normal alkanes and a series of mixtures. The environmental craze growth was characterized by two solvent-dependent parameters,B, a characteristic strain constant independent of temperature andA(T), a characteristic rate constant which varied with temperature following the Arrhenius-type of relationship, i.e.,A(T)=GoX exp(-#x394;Eg/RT). The constant Gowas related to the entropy of activation, whereas the parameter #x394;Egwas interpreted as an activation energy for the crazing process. It was found that within the range of temperature and strain studied the crazing process is diffusion controlled and the size of the solvent molecule is more important than the compatibility of the two materials. For the mixtures of two crazing agents, non-linear behavior appears most probable, but a linear rule of mixtures may be adequate for estimating the characteristic parameters. Inherent difficulties with the experimental technique and data analysis raise concerns about the suitability of the technique as an analytical tool. In this regard, comments about the usefulness of the strain-bending experiment are offered.
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