Research will be conducted on the feasibility of radically improving the physical property profile of selected polymer matrix composites by means of a new and highly innovative technique called "compositional quenching". This technique allows creation of microdispersions of one polymer in another which may lead to improvement in impact resistance, fracture toughness, interlaminar and transverse shear strength. Emphasis will be placed on unique compositions based on Larc technology of polyimides blended with other high performance materials for structural applications. Special attention will be given to achieving uniform polymer dispersions within tough polyimide matrices. These compositions will then be evaluated to determine the effect on composite properties. Initial work will involve (1) identification of promising compositions (2) screening of candidate resins and composites and (3) evaluating properties of selected candidates as composites for further development in phase II.