MECHANICAL AND THERMAL PROPERTIES OF GRAPHITE FIBER-REINFORCED PHTHALONITRILE COMPOSITES

摘要

Current research efforts at the Naval Research Laboratory are focused on expansion of the phthalonitrile composite mechanical and thermal property database as well as collaboration with the user community to optimize phthalonitrile composite processing parameters. In this paper, results of short beam shear tests on bis[4-(4-aminophenoxy)phenyl]sulfone) (p-BAPS)-cured unidirectional graphite fiber-reinforced phthalonitrile composites are reported for comparison with earlier work on 1,3-bis(3-aminophenoxy)benzene (m-APB)-cured composites. The apparent interlaminar shear strength and weight loss measurements are used to assess the thermo-oxidative properties of fully cured composite specimens aged for 100 hours at 500, 550, 600, 650 and 700 deg F. These results are compared with previous shear measurements on slightly undercured composite specimens. In addition, the effect of long-term (up to 1000 hours) oxidative aging on the apparent interlaminar shear strength of BAPS-cured composite specimens is evaluated. Other mechanical property test data reported include tension and flexure. The room temperature studies show that the mechanical and thermal properties of graphite fiber-reinforced phthalonitrile composites are either better than or comparable to those of the state-of-the-art polyimide composites. Results of elevated temperature short beam shear and flexure tests are also reported from room temperature up to 700 deg F. These evaluations explore the elevated temperature behavior of the phthalonitrile resin system.