Effect of heating rate during carbonization on graphitization of carbon films derived from aromatic polyimides

The effect of heating rate during carbonization on graphitization was studied on the carbon films derived from commercially available aromatic polyimide films, Kapton and Novax. The carbon film from Kapton gave the higher value of ( Δρ ρ ) max with the longer residence time between the glass transition and decomposition temperatures, that is, the slower heating rate, but that from Novax showed a maximum at a residence time of around 120 min. The results were discussed on the basis of intramolecular vibration above the glass transition temperature.