Decomposition and Flammability of Polyimide Graphene Composites

Abstract

Polyimide-graphene composites were synthesized by in-situ condensation polymerization and the thermal stability and decomposition behavior of the composites were studied. Polyimides, because of their aromatic backbone, are a class of fire-retardant polymers. Their high char retention ≥50% at testing temperatures ≥600 °C makes them thermally stable polymers. The effect of nanographene sheets on the decomposition behavior of polyimide is presented in this paper. It is shown that the reinforcement of polyimide with nanographene sheets significantly decreased the rate of decomposition of polyimide and increased the char retention of the composite. Thermogravimetric analysis data were used to assess the thermal stability, rate of mass loss and predicted limiting oxygen index of the neat polyimide and composites. Results obtained showed around a 43% decrease in the rate of polyimide degradation at 50 wt.% graphene loading. The limiting oxygen index of the polyimide nanocomposite was calculated by using the char retention, and it was found to increase by up to 24% at 50 wt.% graphene loading over that for the neat matrix.