POLYIMIDE FOAMS AND THEIR PREPARATION

Polyimide foams having enhanced compression fatigue life and softness for use in the manufacture of seat cushions and methods for the production of such foams and precursors therefor. These foams are produced from polyimides prepared by reaction of an organic tetracarboxylic acid or derivative thereof, preferably an ester with (a) 1 to 50 mol percent of a diester of (i) a primary amino-substituted aromatic carboxylic acid, and (ii) a polymethylene glycol, and (b) at least one aromatic or heterocyclic primary diamine. Foams can be produced having (a) a fatigue life as determined by ASTM test procedure D 3574-81 using foam specimens from three to five inches in thickness (7.6 to 12.7 cm) of at least 15,000 cycles, or (b) an indentation force deflection as determined by ASTM test procedure D3574-81 on foam specimens of one-inch thickness of less than 40 pounds of force (178N) at 25% deflection and less than 180 pounds of force (801N) at 65% deflection, or both of (a) and (b).