Abstract:In the present paper,a combination method of chemical imidization and thermal imidization was used to prepare polyimide(PI) films.In the process of chemical imidization,the precursor was converted to amic acid-imide copolymer with different pre-imidization degree(pre-ID) by controlling the content of dehydrating reagent.The in situ generated rigid imide structures induce the orientation of molecular chains,so the final PI films have different aggregation structures and properties.WAXD and DSC test results indicate that the degree of crystallinity of the final PI films increases with increasing pre-ID.The mechanical properties of PI films also increase with increasing pre-ID,and compared with PI0,tensile strength,tensile module and elongation at break of PI-100 increase by 23.2%、7.6% and 158.6%,respectively.