Charge formation and decay in /spl gamma/-irradiated low-density polyethylene

Radiation effects in polymeric materials have been studied for many years to understand various aspects of material behaviour and among these is the electrical response to irradiation. It has been considered generally that space charge played an important role in the electrical behaviours of irradiated material such as dc conductivity, electrical breakdown and thermally stimulated discharge current. Recent observation using either the laser induced pressure pulse technique or the pulsed electroacoustic technique has revealed that a large amount of positive charges can be formed adjacent to the cathode if a dc electric stress is applied. In this paper we report the charge formation and its decay after the removal of the applied stress. It has been noticed that the charge decay is closely associated with the interfacial electric stress produced by charge itself.