Toughened thermosetting resins are disclosed comprising a thermosetting resin having a Tg of at least 150.degree. C., preferably 180.degree. C., and having dispersed substantially uniformly therethrough microspheres of a thermoplastic resin having a Tg of at least 150.degree. C., preferably 180.degree. C. It is preferred to use thermoplastic resins with functional groups on the surface thereof capable of bonding to an available group on the thermosetting resin. High performance structural composites made from such toughened resins are disclosed as well as the process of making such composites.
Marvin L. Deviney; Joel J. Kampa