A Study of the Low-Density Regions Developed in Liquefied Polyethylene Under High Electric Fields

Low-density regions developed in liquefied polyethylene with a point-plane electrode configuration under high electric fields have been investigated using a Schlieren technique in the temperature range from 120 to 200°C. This region, having a refractive index or a density lower than the surrounding medium, is always formed near the point electrode, irrespective of its polarity. For polyethylene in the liuqid state this disturbance region tends to spread and gradually to disappear by moving from the point to the plane electrode at a temperature-dependent ependent velocity, while in the solid state this region does not move.