Electrical properties of TiO2-filled polyimide nanocomposite films prepared via an in situ polymerization process

To fully understand the reliable electrical properties of the nanocomposite films, their physical and chemical behaviors as well as dielectric properties were analyzed. Polyimide/TiO2 (PI/TiO2) nanocomposite films were prepared using in situ dispersion polymerization process. Influences of frequency, temperature and the nano-TiO2 particles loading concentration on dielectric permittivities of the PI/TiO2 nanocomposite films were studied. The dielectric relaxation behavior of the PI/TiO2 nanocomposite films has been investigated with dielectric relaxation spectrum. It was found that interfacial polarization, namely Maxwell-Wagner-Sillars, existed in the PI/TiO2 nanocomposite films with different loading concentration of the nano-TiO2 particles. Dielectric permittivities of the PI/TiO2 nanocomposite films fluctuation with temperature (-50-150 degrees C) were attributed to the mobility and thermal expansion of the polymer matrix, for which the Cole-Davidson model, or modified Cole-Cole model, was brought to account. (C) 2010 Elsevier B.V. All rights reserved.