The influence of liquid uptake on environmental stress cracking of glassy polymers

The effects of liquid uptake on the environmental stress cracking (ESC) of two different polymer systems were studied. These systems were polycarbonate in ethanol and a toughened phenolic in oil and water. Environmental stress cracking was studied using constant strain-rate tensile tests and creep tests. The amount of liquid uptake was varied not by only using the different materials and environments, but also by varying the strain rate and temperature as well as pre-immersing samples in the environment. It was found that there were several important diffusional effects observed in addition to the normal ESC action. These include the introduction of surface compressive stresses, the easier formation of voids in a pre-immersed layer, and the blunting of voided zones and crazes. Which of these mechanisms was observed depended on the degree of liquid uptake.