| Abstract: | Aminimide compounds ( 1–4 ) thermally generating isocyanates and tertiary amines were found to be excellent curing agents for epoxy resin. Tensile behavior, glass transition temperature, and degree of curing for the combination of EPIKOTE 828 prepolymer with a series of curing agents ( 1–4 ) are reported. The resins exhibit a large elongation at breakage and a high fracture energy per unit volume. The epoxy resins (EP-AI) cured with 3 or 4 containing no hydroxyl group showed larger ultimate elongations (up to 15%) and higher fracture energies (ca. 8 J/cm3) than the resins (EP–AIOH) cured with 1 or 2 . The curing reaction depends on the structure of aminimide (presence of hydroxyl group and generation of mono- or bisisocyanates). The origin of toughness and dependence of physical properties on the curing condition and the structure of aminimides were discussed. It was concluded that relatively slow curing at elevated temperature controlled by thermal decomposition of aminimides was a reason for the toughness. |
