Relaxation phenomena in the glass transition of epoxy/N-phenylaminopropyl - POSS nanocomposites

The epoxy resin curing process can be characterized by the formation of an inhomogeneous microstructure with cooperative rearranging regions (CRR). In this study, polyhedral oligomeric silsesquioxane (POSS) N-phenylaminopropyl was utilized as a substitute for the curing agent of the epoxy resin. Various parameters were determined via the Williams-Landel-Ferry (WLF) and Vogel-Tammann-Fulcher (VTF) equations to evaluate the relaxation phenomena of the glass transition. The relaxation and retardation spectra were calculated based on the master curves, and the results are discussed with respect to the microstructure observed by transmission electron microscopy and atomic force microscopy. The incorporation of POSS as a curing agent significantly reduced the number of CRR groups, which demonstrates that this system approaches an ideal glass transition. The evidence presented here shows that the addition of POSS improves the inhomogeneity of the three-dimensional network of the epoxy resin. (C) 2012 Elsevier Ltd. All rights reserved.