A Study of the Thermo-Oxidative Process and Stability of Graphite and Glass/PMF Polyimide Composites

Abstract

Composite materials consisting of graphite and glass fibers in polyimide matrices are being investigated for use in aerospace and other commercial applications at temperatures of 600°F and above. Results of a continuing investigation to determine factors involved in the thermo-oxidative stability of unidirectional fiber/PMR polyimide composites will be presented at this symposium. Composite materials consisting of HTS, HMS, T-300, Celion 600 graphite fibers and S-glass fibers in two polyimide matrices, PMR-11 and PMR-15, were subjected to isothermal aging at 316°C in flowing air at two flow rates (100 cc/min and 900 cc/min) for time periods up to 600 hours. The weight losses, shear and flexural properties were determined at room temperature and 316°C. One system, Celion 6000/PMR-15, was selected for study at 335°C in flowing air at 100 cc/min over a 1015 hour period. The oxidation process of this isothermally exposed composite system was followed by optical microscopy and mechanical property measurements.