Space charge behavior of linear low density polyethylene doped with some types of inorganic nano powder

Packet-like space charge behavior and the isothermal decay processes of the injected charge in the neat linear low density polyethylene (LLDPE) and LLDPE doped with Al₂O₃ nano-particles is investigated by Pressure Wave Propagation (PWP) method. The 1 mm sheet samples sandwiched by semi-conductive electrodes are submitted to 40 kV_dc/mm at 40degC for various duration. The charge injecting rate and the mobility of packet-like space charge under DC stress are compared among the samples subjected to different blending process with or without nano-particles. The slight doping concentration shows significant influence on space charge dynamics, being lower injecting rate and apparent mobility for higher doped samples. The isothermal decay process of the injected charge indicates the trap-modulated feature. The phenomena are related to the changing morphology.