Effect of electron irradiation on the mechanical properties of DGEBA/DDM epoxy resins

The thermomechanical properties of diglycidyl ether of bisphenol A (DGEBA)/4-4 diaminodiphenylmethane (DDM) resins are analysed as a function of the irradiation dose. Irradiation results in a decrease of the glass transition temperature and of the elastic modulus in the rubbery region, ascribed to a destruction of crosslinks. The Arrhenius diagrams show that the α relaxation becomes faster, that the β process is enhanced but that γ relaxation is less modified by the irradiation. The effects of irradiation on the stress–strain curves suggest a spatial heterogeneity of the crosslink density.