Hydration effects and electrical conductivity in polyethylene

The presence of atmospheric moisture or humidity has long been known as a catalyst, or even an initiator, of dielectric breakdown in insulators, especially about the surface. The role played by the water molecules is largely unknown possibly because the way in which it binds to insulators such as polyethylene, in its various forms. Furthermore, the mechanisms responsible for surface conductivity remain a matter for considerable speculation [1–3] even in dry materials. The situation is likely to be far more complex in the presence of water vapour.