Dielectric properties of polylmide/Al2O3 hybrids synthesized by in-situ polymerization

Polyimide/nano-Al2O3 hybrids were prepared via simple in-situ polymerization and the thermal imidation routes. The hybrids film was characterized by transmission electron microscope (TEM) and infrared spectrum (IR). The dielectric behaviors of the composites were investigated as a function of the concentration of the Al2O3 nanoparticles. The results show that, at 980 V (bipolar), the corona-resistant life to the breakdown of polyimide with nano-Al2O3 loading of 30% is 93 min which is over 10 times longer than that of the unfilled film. Such large enhancement may originate from the shielding, thermal conduction and thermal stability effects of the nano-Al2O3 layer. As the nano-A(2)O(3) loading increases, the volume resistivity and the electrical breakdown strength show a little decline, while the dielectric constant of the hybrid films increases, which could be attributed to the significant interfacial zone between the polyimide and the filler. (c) 2006 Elsevier B.V All rights reserved.