Crosslinking-property relationships in PMR polyimide composites. IThe thermooxidatively-induced crosslinking/ physical and mechanical property relationships of graphite fiber-reinforced PMR polyimide-matrix composites were studied during isothermal exposure of the composite specimens at 288 C in air for periods of up to 5000 hr. The crosslinking densities due to this treatment were estimated on the basis of the kinetic theory of rubber elasticity and shifts in the glass transition temperature T(g). Several linear relationships are noted between crosslink density and physical and mechanical properties: T(g), initial weight loss, and elevated temperature interlaminar shear strength increase with crosslink density, while initial moisture absorption decreases. After achieving the highest crosslink density, several of the composite properties begin to decrease from their maximum values.
Document ID
19870044923
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Pater, R. H. (NASA Langley Research Center Hampton, VA, United States)
Whitley, K. (NASA Langley Research Center Hampton, VA, United States)
Morgan, C. (NASA Langley Research Center Hampton, VA, United States)
Chang, A. (PRC Kentron, Inc. Hampton, VA, United States)