Macromolecular Mobility Changes Induced by Thermal Aging of Epoxy-amine Polymer Networks

Changes in macromolecular mobility during the thermal oxidation of epoxy-amine thermoset networks are addressed in this study. Three epoxy-amine systems, cured with DGEBA and three similar aliphatic hardeners – ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA) – aged at 160°C are characterized by dynamic mechanical analysis (DMA). Results show a split of the single initial α relaxation peak with aging, which may imply that chain scissions are preferred at certain oxidizable sites in the network. A β relaxation can be identified around -60°C and does not seem to evolve much with aging, while another sub-glass transition around 30°C decreases with it. Implications of this work both with mechanical fracture properties and with segmental mobility of radical chemical functions involved in bimolecular oxidation reactions have yet to be confirmed.