The fabrication and electrical properties of polyimide/boron nitride nanosheets composite films

Boron nitride nanosheets (BNNSs) and related polyimide (PI)/BNNSs composite films are synthesized by a molten salt intercalation-mechanical assisted stripping method and an in situ method respectively. The structures and morphologies of BNNSs and PI/BNNSs composite film were characterized by transmission electron microscopy (TEM), Atomic force microscopy (AFM), X-ray powder diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR). The thermsal stability and electrical properties of the PI/BNNSs composite film were further investigated by thermogravimetric analysis (TG), dynamic mechniacal anlysis (DMA), insulation resistance tester, withstand voltage tester, broadband dielectric–impedance spectroscopy and corona resistance system (CRS) separately. For example, the corona resistance lifetime of PI/2.5BNNSs composite film is 36 min, which is 24 times than that of pure PI film. The result indicates that BNNSs, as a two-dimension material with high aspect ratio and the anisotropic characteristic, can be applied as one corona-resistant material.