Structure characteristics and dielectric properties of PI/MMT nanocomposite films

Recent developments in polymeric dielectric nanocomposites have shown that these novel materials can improve design of high voltage components and systems. MMT(Montmorillonite)has an excellent corona performance and PI/MMT nanocomposite films can be prepared by in-situ polymerization process in this paper. Dielectric properties and trap level characteristic were measured by broadband dielectric spectrometer, thermally stimulated current (TSC) and the system of corona resistance. The microstructures of the films are observed by SEM. The experimental results show that the trap densities of nanocomposite films are more than that PI. With the MMT component increasing, the permittivity of nanocomposite films become smaller and dielectric loss of nanocomposite films increase obviously in the range of low frequency (10^-3~10⁰Hz), corona aging life of nanocomposite films are longer than that PI. The layered MMT nanoparticles doping in PI matrix provide a lot of traps which have an important influence on the electrons transplanting, furthermore, affecting dielectric properties of films. The research show that the corona aging life and dielectric properties can be enhanced by increasing proper trap density and depth provided by nanoparticles.