ABSTRACT

Polyimide (PI) film is characterized by excellent insulation property, widely used in electrical, electronics and transportation industries (Aragoneses 2008, Zha 2010). With the wide application of the frequency conversion control technology, the requirements of development and application of insulating material have been higher, and the traditional, single insulating material has not satisfied the practical application and the need of scientific development yet. The insulation breakdown is caused by the partial discharge, dielectric heating and space charge, thus the insulating material needs to have the partial discharge resistance, strong heat resistance and charge dissipation function (Chen 2010, David 1999, Molinie 1999). The research shows that adding inorganic nano oxide to polyimide can significantly improve the corona resistance, breakdown field strength and dielectric constant of materials (Tuncer 2007, Zhao 2009, Maiity 2008), but the there are little research on the thermal stability and mechanism of the material.