Mechanical properties of graphite fiber-reinforced phthalonitrile composites

Graphite fiber-reinforced phthalonitrile composites exhibit attractive high temperature properties, when compared to other polymer matrix composites. To evaluate the mechanical properties of these, composites, short beam shear tests at room temperature and at temperatures between 316 degreesC (600 degreesF) and 538 degreesC (1000 degreesF), sustained load tension tests at 316 degreesC, thermal-oxidative exposure tests, and solvent exposure tests were conducted. Results of the short beam shear tests on [O](16) material indicated that the apparent interlaminar shear strength dropped as the test temperature is, increased. At intermediate temperatures, the behavior of the sample was found to be sensitive to variations in the cure cycle, The sustained load tests, where a load of 40 kN (9000 lb) was placed on [O](8) tension test specimens and the temperature was held at 316 degreesC, exhibited failure times between 443 and 613h. The short beam shear behavior was not affected upon exposure of the [O](16) composite samples, to various solvents.