Effect of content on dielectric performance of Barium titanate/polyimide films

Polymer-matrix insulating materials are widely used in electrical and electron engineering because of their excellent mechanical properties, thermal and dielectric properties. Barium titanate/polyimide (BaTiO₃/PI) nanocomposites have been prepared by an in-situ polymerization process at room temperature. The BaTiO₃ phase was observed by scanning electron microscope (SEM), it shows that the BaTiO₃ phase was well dispersed in the polymer matrix. The composite with 70 wt% BaTiO₃ appears a high dielectric constant of about 15 in the frequency of 10³ Hz to 10⁶ Hz and a high breakdown strength of more than 50KV/mm under alternating current (AC) field at room temperature. Meanwhile, the loss tangent of all the simples measured was under 0.015. The volume resistivity of the composite decreased with the increase of the concentration of BaTiO₃, but it was still greater than 1.8×10¹² ohm·m.