Water permeation through electrically damaged polymers

The exposure of dielectrics to moisture in the presence of an electrical field can result in the growth of water trees possibly leading to premature failure (1). Although investigated extensively, the mechanisms of initiation and growth of water trees remain unclear. In relation to this, the mode of water transport through treed polymeric materials is a subject of considerable controversy. It has been suggested that the voids constituting the water trees are interconnected by channels which develop under the influence of electrical stress and collapse due to surface tension once the field is removed (2). If this is the case, one must consider the possibility that the observed stress dependence of the rate of water-tree growth is controlled by the effect of the stress of the rate of water transport through a damaged dielectric. To date, all work dealing with fluid transport studies show no indication of the existence of these channels. However studies were carried out either with undamaged materials (3) or without an applied field (4,5).