Effects of Polycyclic Compounds on DC Conductivity of Polypropylene Film

In this paper, polycyclic compounds are employed to modulate the DC conductivity of polypropylene (PP) film to improve the working performance and safety of power capacitors at high temperatures. Three kinds of polycyclic compounds, Benzoin, 4-Benzoylbiphenyl and 4,4’- Bis (dimethyl amino) benzil, were dispersed into PP matrix by banbury mixer with the filler content of 0.05 wt%. The three- electrode system was used to measure the conduction current of samples at different temperature. The conduction current density and DC conductivity were calculated. The DC conductivity of PP film was decreased after the addition of polycyclic compounds, and the DC conductivity of PP modified by 4-Benzoylbiphenyl was lowest. The surface potential decay (SPD) was employed to analyze the trap energy level distribution. Polycyclic compounds introduced deep trap energy levels in PP film and increased the deep trap density. The introduction of deep trap levels by polycyclic compounds can limit the transport of charge carriers and then affect the DC conductivity of PP film.