Preparation and characterization of γ-Al2O3/polyimide nanocomposite films

γ-Al2O3 sol with a wormhole-like pore structure was prepared from aluminum alkoxide precursor by a hydrothermal process and γ-Al2O3/polyimide (PI) nanocomposite films with a network structure were synthesized by an in situ synthesis process. The sol was characterized by the transmission electron microscope, X-ray diffraction and Fourier transform infrared spectroscopy. The morphologies of the nanocomposite films were characterized by the scanning electron microscope, and the corona resistance time of the nanocomposite films was measured. The results show that the γ-Al2O3 sol is a porous molecular sieve with a wormhole-like pore structure and there are many hydrogen bonds in the chemical structure of γ-Al2O3 particles. A continuous network of inorganic phase is clearly observed in the nanocomposite films when the γ-Al2O3 mass fraction (the same below) exceeds 12%. With increasing doping content, the corona resistance time of the composite films increases obviously. The corona resistance time of the film with 25% doping concentration is 25.4 times longer than that of the pure PI film. Based on the results, the effects of the morphology and chemical structure of the sol on the morphology and corona resistance time of the composite films were also analyzed.