Investigation of charge transport in LDPE/SiO₂ nanocomposite based on the simultaneous observation of charge and current behaviour

Abstract

The charge transport characteristics of LDPE/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanocomposites were investigated by simultaneous measurement of space charge and relaxation current. The filling concentration of hydrophilic nano-SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ranged from 0.0 to 5.0 wt%. The effects of filling concentration on the relationship between charge accumulation and the quasi-steady current were analysed during the polarisation process. The trap energy distribution was calculated according to depolarisation current. For simplicity, a mean energy level is proposed through the overall averaging process in the detection period. Moreover, the total trap density within the measured energy level range was obtained by the integral of the energy distribution. The results show that the mean energy level and total trap density are non-monotonic with concentration. Based on the calculation results, the characteristics of charge accumulation and quasi-steady current were explained from the perspective of the trap energy distribution. Finally, a synchronous simulation of the space charge and relaxation current was carried out based on the above trap distribution parameters for pure LDPE and LDPE/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanocomposite with a concentration of 1.0 wt%. The simulation phenomena of charge accumulation characteristics and current decay trend were in close accordance with the experimental results, verifying the effectiveness of the analysis.