The effect of different orientations in rigid rod polyimide films on the graphitized products

The effect of uniaxial and in-plane orientation of different rigid-rod homo- and co-polyimide films on the development of graphite structure after heat treatment up to 3070 K was investigated. The magnetoresistance and X-ray diffraction measurements were carried out to estimate the degree of graphitization and in-plane orientation of graphite crystallites. Both pristine and in-plane pre-oriented polyimide films show high degrees of graphitization. In-plane cold-drawing leads to the increase of in-plane orientation of polyimide films, but it produces the different actions on the graphitization parameters of homo- and co-polyimide films. While the cold pre-drawing of homo-polyimide films increases their graphitizability, this pre-treatment of the co-polyimide films does not lead to the improvement of graphitized material’s characteristics. The uniaxial orientation results in the hindrance of graphitization. The role of the supramolecular structure of ordered regions of polyimide films in the development of graphite structure under graphitization process has been discussed.