Abstract
Dielectric techniques - thermally stimulated depolarization currents and broadband dielectric relaxation spectroscopy togheter with differential scanning calorimetry were employed, to investigate molecular dynamics in rubbery epoxy networks, modified with polyhedral oligomeric silsesquioxanes units covalently bound to the chains. Four relaxations were detected and analyzed: two local, secondary relaxations in the glassy state, the segmental relaxation associated with the glass transition and the normal mode relaxation, related with the presence of a dipole moment component along the Jeffamine chain contour.
Obtained results suggest that a fraction of polymer is immobilized, probably at interfaces with POSS, due to constraints imposed by the covalently bound rigid nanoparticles, whereas the rest exhibits a slightly faster dynamics due to increaseof free volume.