Influence of electron irradiation on the mobility and on the mechanical properties of DGEBA/TETA epoxy resins

The thermomechanical properties of DGEBA/TETA resins are analysed as a function of the irradiation dose. Irradiation by electrons results in a decrease of the glass transition temperature and the elastic modulus in the rubbery region. The Arrhenius diagrams obtained for the various doses show that the cooperative mobility associated with the α relaxation becomes faster after the irradiation. More local mobility corresponding to the β and γ relaxations is also modified, but in a lesser extent. These results can be interpreted invoking a destruction of the crosslinks within the resin. The effects of irradiation on the stress–strain curves are also discussed and are shown to be connected with both the physical aging kinetics and the spatial heterogeneity of the crosslink density in the resin.