In this paper

for exploring the corona resistance characteristics of polyimide/nano composite films under repetitive square impulse

pure polyimide and polyimide doped with nano alumina films are made by in-situ polymerization

and the chemical structure of the two kinds of films are analyzed by Fourier transform infrared spectroscopy（FTIR）. Besides

the surface resistivity is measured. Then corona resistance test of film under repetitive square impulse is carried out and finally

the morphology before and after corona aging is analyzed through scanning electron microscope（SEM）and the mechanism of corona resistance of film is investigated further. It is shown by the experimental result that the lifetime of both pure polyimide and nano composite decrease with the increase of voltage and

at the same voltage

the corona resistant characteristic of nano composite is superior to that of pure polyimide. The corona resistant characteristic of nano composite from such three aspects as interface between nanoparticles and polymer matrix

surface charge distribution and breakdown process is explained.