Shanjun Li*
Department of Macromolecular Science and The Key Laboratory of Molecular Engineering of Polymer, Ministry of Education, Fudan University, Shanghai, 200433, ChinaAbstract: The viscoelastic phase separation of thermoplastics modified diglycidyl ether of bisphenol A (DGEBA)epoxy systems were investigated by Synchrotron Radiation Small Angle X-ray Scatter(SR-SAXS), Transmission electron microscopy (TEM), Time Resolved Light Scattering (TRLS), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM). SR-SAXS and TEM results show that the early stage of phase separation follows Spinodal decomposition mechanism, but inverted phase structures were caused by the “dynamic asymmetry” between PEI and epoxy even though PEI concentration lower than critical point. It was found experimently that the evolution of scattering vector qm corresponding to the size of epoxy droplets follows Maxwell-type viscoelastic relaxation model. The relaxation time may be considered as the the time for escape of the epoxy-anhydride n-mers from PEI-rich phase by their relaxation movement.
