Study of molecular mobility in polymeric network by thermostimulated current spectroscopy

The ThermoStimulated Current spectroscopy has been applied to the investigation of epoxy based network around the glass transition, Tg, in order to characterize the molecular mobility of the crosslinked network. The polymeric network chosen is a commercial polyepoxy TGMDA-TGPAP-DDA. On the TSC spectrum three relaxation modes are observed: the γ and β modes respectively situated around -166°C and -100°C and the α mode located around 90°C. The γ relaxation has been assigned to, movements of residual epoxy groups. The β mode is constituted of two sub-modes: the β₁ component at lower temperature is attributed to intermolecular mobility of segments containing benzene rings: it obeys a compensation law. The β₂ component at higher temperature is due to non-cooperative crankshaft type rotation of the hydroxyether sequences. The TSC α relaxation mode has been attributed to the dielectric manifestation of the glass transition