Surface wetting and the prediction of environmental stress cracking (ESC) in polymers

Simple observation of surface wetting phenomena, i.e. the behaviour of droplets and applied films on polymer surfaces is shown to be a promising approach to predict whether ESC will occur in given liquid/polymer systems. The present study included polycarbonate (PC), cyclic olefinic copolymer (COC), and acrylonitrile/butadiene/styrene (ABS) polymers. The most certain indication of a potential ESC problem is when a droplet of challenge liquid spontaneously spreads on the polymer surface. The ability to predict whether ESC will occur based on the behaviour of applied films appears to be possible but is less certain. Films that do not retract are a good indication of potential ESC phenomena. Films that do retract may just be an indication of a contaminated surface. This leads to a false sense of security. Therefore the film wetting/dewetting phenomena must be used with special care if potential ESC problems are to be predicted by this method.