Tailoring of Graphite Films-Control of Structure and Functions-

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The development of graphite structure (Graphitization)Highly crystallized graphite films were confirmed to be obtained from some polyimide films by satisfying the following three conditions ; flatness of polyimide molecules, high degree of orientation of thses molecules and less disturbance in orientation during the heat treatment (carbonization and graphitization) . It was found that nitrogen remained in the resultant carbon films by substituting carbon atoms in hexagonal carbon layrs up to the heat treatment of 2200 ﾟC and its presence affects on the development of graphite structure and galvanomagnetic properties in the carbon films. The effect of heating rate during carbonization was compared on various precursors.Imprevement of molecular orientation and graphitizabilityIn order to improve the orientation of plyimide molecules, cold-drawing of films and esterification of molecules were tried.Uniaxial cold-drawing of the film during imidization was found to improve the molecular ori … More entation in polyimide films, but at the same time axial orientation scheme was found to be introduced, and, as a consequence, graphitization in the films was perturbed.The esterification was effective to improve the molecular orientation in polyimde films and also the graphitizability of the films by the heat treatment at high temperatures. Fundamental chemistry on the esterification of plyimide molecules and the synthesis of urathane-imide copolymers was studied in detail.Function development of graphite filmsThe quality of the graphite films obtained from polyimides were evaluated by different techniques, X-ray diffraction, optical microscopy, transimission electron microscopy, scanning electron microscopy, electron channeling contrast and measurements of galvanomagnetic and magnetic properties and compared with kish graphite precipitated from molten iron, carbon nanotube and cokes.Galvanomagnetic properties of graphite filmjs obtained from polyimides were markedly improved by the intercalation of MoC15 and the experimental results were compared with those on the incorporation of iron into kish graphite and on the fluorination and lithiation of carbon nanotube. Less