New Developments in Soluble Thermoplastic High Glass Transition Temperature Polyimides

Utilizing solution imidization, molecular weight and end group control techniques, soluble, fully cyclized polyimides with very high glass transition temperatures have been developed to meet high temperature applications. Mechanistic aspects are investigated for solution imidization by both the polyamic acid route and by the ester-acid route. Polyimides based on pyromellitic dianhydride and a 3F diamine exhibit glass transition temperatures of 420°C. These polyimides are soluble in polar aprotic solvents and form tough, transparent films which demonstrate mechanical integrity and thermooxidative stability at 700°F. Various processing routes are explored to demonstrate the viability of these materials in high temperature applications. Details of the synthesis and characterization of these materials will be provided.