Preparation of three-layer polyimide/nano-alumina composite films

Three-layer polyimide/nano-aluminacomposite film was prepared with thermal imiditation after pure poly(amic acid) or Al₂O₃/poly(amic acid) solution was cast on glass plate step by step. The micro-morphology of PI films were characterized by scanning electron micrographs (SEM). The thermal stability, mechanical properties and electric breakdown strength of PI films were investigated. The results indicated that the thermal stability and electric breakdown strength of PI composite film were better than pure film and hybrid film. The decomposition temperature of PI composite film was 629.1°C at 10% weight loss. The mechanical properties of PI composite film were improved obviously in comparison of the hybrid film, the tensile strength of PI composite film was 117.4 MPa, and the elongation at break was 18.5%.