PROCESSING OF POLY(AMIDE IMIDES) AS MATRICES FOR HIGH-PERFORMANCE COMPOSITES

Poly (amide imide) (PAI) has proven to be an excellent engineering thermoplastic. Injection and compression molding processes are currently used to produce poly (amide imide) parts when superior toughness, solvent resistance, and high-temperature heat performance are required. The objective of this work was to determine the essential features necessary to use these systems as matrices for carbon-fiber-reinforced composites. The principal steps utilized were: impregnation of the carbon fibers with a PAI solution, drying the solvent from the individual plies, stacking the plies for final consolidation, and a postcure. A processing cycle was developed applicable to resins with different solvent concentration and molecular weight, giving special attention to the solvent evaporation step. A model capable of predicting the rate of evaporation as a function of temperature was developed using the principle of time-temperature superposition. A viscosity model similar to that for a curing thermoset was developed by combining Arrhenius expressions for the temperature and concentration effects. Collectively, this work then provided insight for matrix requirements in the formulation of PAI composites by solvent impregnation.