Time-resolved mechanical spectroscopy of epoxidized natural rubber/SiO2 composite

The rheological behavior of an epoxidized natural rubber (ENR) nanocomposite containing 10 wt.% of silica particles was examined by time-resolved mechanical spectroscopy (TRMS), exploiting the unique capability of this technique for monitoring the time-dependent characteristics of unstable polymer melts. The resulting storage modulus curve has revealed a progressive evolution of the elastic component of the composite, associated with slower relaxations of the ENR macromolecular chains. Two major events were identified and quantified: one is associated with the absorption of the ENR chains onto the silica surface, which imposes further restrictions on the motions of the chains; the second is related to gelation resulting from the simultaneous occurrence of temperature-induced cross-linking and chain scission reactions within ENR.