Study of the dynamic fragility of polymer nanocomposites: Correlation with damping

Abstract In this work, an extensive study on the glass transition temperature (T_g), dynamic fragility and activation energy (E_a) for a variety polymeric nanocomposite materials, based on four different types of polymeric matrices reinforced with carbonaceous nanofillers, and SiO₂ has been performed. Referring to the dynamic mechanical analysis data obtained in the author's previous works, the dynamic fragility and activation energy were calculated and examined. Depending on the polymeric type, different behavior was detected, as far as the fragility dependence on nanofiller type and loading is concerned, whereas the T_g variation was also investigated. A general trend of a decreasing dynamic fragility with increasing T_g was found, with the exception of Polylactic acid (PLA)/hybrid nanocomposites. A relation between nanofillers synergy and dynamic fragility variation has been achieved, namely the more homogenous nanofillers dispersion (and the synergistic effect between nanofillers), was associated with higher dynamic fragility values. Furthermore, the inter‐particle distance increment may lead to an increased fragility and the Resin/SiO2 nanocomposites appear to follow this rule. In addition, strain sweep experiments were conducted to analyze the connection between fragility and damping of the polymer nanocomposites. The PLA/hybrid carbonaceous nanocomposites reveal an essential damping enhancement, associated with fragility lowering.