Thermally stable polyimides from solutions of monomeric reactants

Abstract

Abstract A method to prepare thermally stable resin fiber‐reinforced composites using solutions of appropriate monomers is described. Solutions containing a dimethyl ester of an aryl tetracarboxylic acid, the monomethyl ester of 5‐norbornene‐2,3‐dicarboxylic acid and an aryl diamine were used to impregnate graphite fibers. Composites fabricated from these prepregs exhibited excellent thermo‐oxidative stability and retention of mechanical properties at 600°F. These results compare favorably with those obtained from composites made from amide‐acid prepolymers capped with reactive alicyclic rings. Monomeric solutions provide excellent shelf life and improved solubility compared to amide‐acid prepolymer solutions.