DGEBA was cured with bimodal blends of polyetheramines as well as with single molecular weight amines while maintaining stoichiometry. Glass transition temperatures (T(g)s) and moduli were measured using dynamic mechanical analysis (DMA). Fracture properties were measured using the compact tension geometry and testing was performed at both ambient and non-ambient temperatures, investigating toughness changes as a function of temperature. For constant amine average molecular weights, the addition of high molecular weight amines caused increased glassy moduli at a constant T - T-g and decreased densities while broadening the glass transition without changing the fracture toughness. The fracture behavior, specifically the slip-stick to brittle transition, was affected by the broadened transitions. T-g, breadth of T-g, and total damping were found to be proportional to the volume fraction of amine in the system. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1621-1631, 2013