The University of Alabama in Huntsville Investigations of Toughening Mechanisms of Epoxy Resins

Composite material technology has been applied to the solid rocket booster by the development of a carbon filamentepoxy resin case which yields a net increase of 4000 Ibs. in payload in the shuttle. The question of reusability of the new composite tanks has not yet been answered and will depend on the toughness of the matrix resin. The present study was aimed at providing conditions whereby test specimens of the epoxy resin (EPON/825) and curing agents of systematically varied structures could be produced in a controlled manner. Three sets of conditions were found that might allow the isolation of the structural effects on toughness from the cure effects. The kinetic methods leading to the determination of these conditions are described.