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

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.

Automated summary

An extensive study was conducted on the glass transition temperature (T-g), dynamic fragility and activation energy (E-a) of polymeric nanocomposite materials reinforced with different types of carbonaceous nanofillers and SiO2. The relationship between dynamic fragility and nanofiller type and loading was investigated, as well as the variation in T-g. It was found that the dynamic fragility generally decreased with increasing T-g, except for Polylactic acid (PLA)/hybrid nanocomposites. The dispersion of nanofillers and their synergy were found to affect the dynamic fragility, and the Resin/SiO2 nanocomposites followed a rule of increased fragility with increased inter-particle distance. Furthermore, the connection between fragility and damping of the polymer nanocomposites was analyzed through strain sweep experiments, revealing an essential damping enhancement in PLA/hybrid carbonaceous nanocomposites associated with fragility lowering.