Viscuelastic Behavior of Epoxy Resins Modified by Various Fiexibilizers

Abstract

Effects of various flexibilizers on viscoelastic properties and on the ductilization mechanism were investigated for anhydride-cured epoxy resins. Rubber particle dispersion type flexibilizers lower the moduli of epoxy resins in the glass state, but cause hardly any drops in the glass transition temperature (T_g). By contrast, compatible flexibilizers lower moduli very little, except those including γ-dispersion or spreading α-dispersion due to the glass transition, while they lower the T_gs significantly. These results indicate that the rubber-modified type flexibilizers are the most appropriate to lower the modulus in the glass state without lowering T_g.