The study of the structural transformation for carbonized polymer films

Polyimide (Kapton) and polyamide (Mk) polymer films were carbonized to 900 °C under Ar in furnace. In this study, a further heat-treatment process for these carbonized films was performed by combining a DC resistance-heating device for passing a DC current through the sample film and a Thermal mechanical analyzer (TMA) for mounting the film vertically in its chamber. The heating processes were carried out by step increasing the supply voltage to the destined value. Meanwhile, the length variation of the sample film, the generated current passed through the film, and the temperature profile detected from an optical sensor facing the film were monitored and recorded in-situ during the heating process by this TMA. Both films shows distinctly elongation, temperature, and current increasing patterns. The result indicates a ca. 10% elongation for Kp films being heat-treated to ca. 2200 °C, and a temporary resistance increasing for carbonized Mk films around 1350 °C under vacuum condition.