Evaluation of Polyimide Foam as a Fire Barrier for Spacecraft Cushion Materials

Polyimide foam is an intrinsically flame resistant foam material. This study uses the NASA upward flame propagation test and the cone calorimeter test to evaluate the application of polyimide foam as a fire barrier for spacecraft cushion materials. The flame propagation test results demonstrate that a thin-layer of polyimide foam (3-mm thick) could totally stop the flame spread on the underneath polyurethane foam in an environment containing 30% oxygen. The cone calorimeter test results show that polyimide foam increased the minimum heat flux for ignition of a cushion sample from 27 to 48kW/m2. This suggests that application of polyimide foam can significantly reduce the ignition risk. It was also found that polyimide foam significantly reduced the peak heat release rate, mass burning rate, and the generation of carbon monoxide and smoke in the flaming combustion. For polyimide foam-covered polyurethane, smoldering combustion was insignificant at 25 and 35kW/m 2 incident heat fluxes; it became more important when the incident heat flux reached 45 kW/m2. The smoldering combustion of polyurethane foam and polyimide foam-covered polyurethane could not be self-sustaining if the external heat source was removed.