LOW-TEMPERATURE FAST-NEUTRON AND GAMMA-IRRADIATION OF GLASS FIBER-EPOXY COMPOSITE .2. STRUCTURE AND CHEMISTRY

Structure and chemistry of S2-glass fiber-epoxy composite exposed to f ast-neutron and gamma irradiation at 4.2 K have been studied. Fast-neu tron fluence ranged from 0.9 x 10(22) to 1 x 10(23) n/m(2). At the neu tron fluence of 3.1 x 10(22) n/m(2), ordering of the amorphous S2-glas s structure intervened. Ordering was followed by partial crystallizati on at the neutron fluence of 1 x 10(23) n/m(2). Although the epoxy mat rix retained its amorphous structure, reactor irradiation induced cros slink formation and hydrogen evolution. These processes became signifi cant at neutron fluences equal to or higher than 1.8 x 10(22) n/m(2). No evidence has been found for hydrogen bubble or void nucleation at t he glass-epoxy interface at the neutron fluence of 3.1 x 10(22) n/m(2) . Furthermore, sharp compositional changes measured at the glass-epoxy interface preclude an extended irradiation-induced atom mixing at thi s neutron fluence.