Charge trapping and detrapping in polymeric materials

Space charge formation in polymeric materials can cause some serious concern for design engineers as the electric field may severely be distorted, leading to part of the material being overstressed. At the worst, this may result in material degradation and possibly premature failure. It is therefore important to understand charge generation, trapping, and detrapping processes in the material. In the present paper, the characteristics of charge trapping and detrapping in low density polyethylene under dc electric field have been investigated using the pulsed electroacoustic technique. It has been found that the charge decay shows very different characteristics for the sample with different periods of electric field application. To explain the results a simple trapping and detrapping model based on two trapping levels has been proposed. Qualitative analysis revealed the similar features to those observed experimentally.