Influence of Interface on the Electrical Properties of Polyimide/TiO2 Composite Films

Polyimide/TiO2 (PI/TiO2) composite films were fabricated by in-situ polymerization and are reported in this paper. The effect of interface (PI-TiO2) on dielectric and breakdown properties was investigated via conductivity, photo-stimulated discharge (PSD), permittivity, thermo-gravimetric analysis (TGA) and breakdown characteristic. The results show that interface between PI and TiO2 in composites contains deep charge traps with density proportional to TiO2 doping concentration. Interface enhances space-charge polarization to increase conductivity and loss tangent at low frequency. The pinning influence of interface on PI molecular chain motion is reflected in the downtrend of permittivity (0%-4% nano-TiO2 doping concentration) and increasing decomposition temperature (T-PI