Environmental stress cracking of PVC and PVC-CPE

The craze initiation of PVC and PVC-CPE in a number of vapour and liquid environments was studied. The observed decrease in the craze-initiation stress could be ascribed to the absorption of components by the PVC and the PVC-CPE matrix. The magnitude of the absorption depends on the activity of the components and on their interaction with the PVC matrix. The activity of the components was defined according to thermodynamics. The interaction of the components can be obtained from measurements of the angle of contact, though it is preferred to quantify this interaction by absorption experiments. A simple model is presented to predict the long-term craze-initiation stress of PVC in environments.