The Skybond® product line encompasses a number of products usable as matrix resins for manufacture of high thermal stability structural composites. Composites based on the Skybond® family of resins have continuous use temperatures in excess of 600° F with short term capability greater than 1000° F. Prepreg has been successfully manufactured from all common high performance substrates, such as, E-glass, high modulus carbon, and quartz. Two new classes of matrix resins have been developed in the Skybond® family. The first can be processed by RTM molding techniques to bring the outstanding thermal resistance of polyimide resins to RTM molded composites. The second new class of Skybond® matrix resins is the two-stage cure resins that when used in prepreg applications allow the manufacture of very low void level composites by autoclave processing (<0.5% voids) combined with excellent thermal stability of polyimide resins.