| At present, polyimide matrix has been hybridized with fillers such as TiO2, SiO2 and montmorillonite. Moreover some of the favorable results have been obtained. But previous studies about polyimide/inorganic hybrids were concentrated on the binary systems, in which exists a sort of inorganic components. Due to the key challenge for complicated techniques and preparation, there were few reports about ternary systems.A series of polyimide/SiO2-TiO2 hybrid films with different contents of inorganic particle were fabricated using tetraethoxyl silicane and tetrabutyl titanate as precursor in situ with sol-gel method and both phases in situ. Chemical structure and micro-morphology of hybrid films were studied by means of IR, SEM and XRD. Thermal stability, breakdown strength and corona resistance of polyimide hybrid films was also tested.Fourier transform infrared spectra analysis show imidization of hybrid films is complete and Si-O-Ti bonds exsisted in the hybrid films. The results of SEM indicated that inorganic particles distributed uniformly in the polyimide matrix using hydrochloric catalyst and the average diameter of the particles is less than 100 nm, but inorganic particles is reunited in the polyimide matrix using acetic acid catalyst. As has been seen from X-ray diffracition spectra results, it shows crystallinity exsisted in pure polyimide film and hybrid polyimide films using hydrochloric catalyst but damaged in films using acetic acid catalyst.Results of diversified test indicate thermal stability, breakdown strength, corona-resistance of hybrid films using hydrochloric catalyst are excellent. With the increasing of content decomposition temperature of the hybrid films is increased, and the maximum value is 595.7℃. When the inorganic content of the hybrid films is 4wt% for SiO2/TiO2 (2/1), its electrical properties are the most outstanding. Its breakdown strength is 233.7 kV/mm. Its corona-resistance time is 135.5h and reaches 61 times than pure polyimide film.
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