Time-temperature Dependences of Fracture Toughnesses of Epoxy Resin and Silica Particulate-filled Epoxy Composite

摘要

In the present study, the time-temperature dependencies of fracture toughnesses, K_(Ic), were investigated for bisphenol-A type epoxy resin and silica particulate-filled epoxy composite. Glass transition temperature, T_g, and Angell's fragility parameter, m, derived from thermo-viscoelasticity, were used to characterize the epoxy resin and its composite, which were cured under various conditions. We conducted a fracture toughness test at various temperatures and displacement rates. The results revealed that the K_(Ic) of the epoxy resin and composite depend on both temperature and time. The K_(Ic) follows a time-temperature equivalent principle. We found that the temperature-time dependence of K_(Ic) depends on m, although brittle-ductile transition is governed by α-relaxation phenomena expressed by T_g.