Dielectric properties and effect of electrical aging on space charge accumulation in polyimide/TiO2 nanocomposite films

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Description/Abstract

In situ polymerized polyimide/TiO2 �PI/TiO2� nanocomposite films with good electrical aging resistance are studied. Space charge distribution in the PI/TiO2 nanocomposite films are measured using the pulsed electroacoustic method. Dielectric properties of the films are measured in the frequency range of 102 Hz–106 Hz by an impedance analyzer �Agilent 4294A� at room temperature. These nanocomposite films are also characterized by Fourier transform infrared spectroscopy and scanning electron microscopy �SEM�. It is demonstrated that the nano-TiO2 particles strongly affect dielectric breakdown, lifetime and space charge distribution, and increase the voltage endurance of the nanocomposite films significantly. SEM analyses show that the nanocomposite films are destroyed after corona aging. The relation of space charge distribution with the concentration of the nano-TiO2 particles and the aging time is explored. Results show that an increase in dielectric permittivity of the nanocomposite films is observed with increasing filler concentration. However, the accumulation of space charge decreases with increasing nano-TiO2 particles concentration for the same corona aging time, and depends on the dielectric permittivity of the nanocomposite films.