PHTHALONITRILE-CARBON FIBER COMPOSITES

Phthalonitrile polymers offer promise as matrix materials for advanced composite applications. The phthalonitrile monomer is readily convert ed to a highly crosslinked thermosetting polymer in the presence of th ermally stable organic amine catalysts. Rheometric studies were conduc ted to elucidate the optimum amine concentration for composite formula tions. High quality composite panels were processed in an autoclave us ing unsized IM7 carbon fibers. Mechanical properties of the phthalonit rile/carbon composite are either better than or comparable to the stat e-of-the-art PMR-15 composites. Dynamic mechanical analysis reveal tha t samples postcured at elevated temperatures (375 degrees C) do not ex hibit a glass transition temperature up to 450 degrees C and also reta in similar to 90% of their initial modulus at 450 degrees C. Flame res istance of phthalonitrile/carbon composites, evaluated by cone calorim etric studies, excels over that of other polymeric composites for mari ne applications. The composites also show low water uptake, <1% after exposure to water for 16 months.