Electric field-induced viscoelastic changes in insulating polymer films

A new measurement technique, using the quartz crystal thickness-shear-mode sensor is described which permits the determination of the viscoelastic properties of polymers such as polyethylene and polypropylene when subjected to high electrical fields. It is demonstrated that the field causes changes in the viscoelastic properties and the polymers becomes increasingly viscous and compliant as the field increases. The results are consistent with a model, which has been proposed earlier, in which an electrical field in a dielectric creates a mechanical stress which weakens its cohesion. There are significant implications for electrical aging and breakdown, especially under alternating field conditions