Flow-Induced Enhancement of in Situ Thermal Reduction of Graphene Oxide during the Melt-Processing of Polymer Nanocomposites

In situ thermal reduction (ISTR) of graphene oxide (GO) dispersed in a polymer matrix has attracted broad interest due to its great potential as an environmentally friendly and commercially viable process to prepare polymer/graphene nanocomposites (PGNs). In this work, the ISTR of GO in two dramatically different conditions, quiescent melt and sheared melt, was comparatively studied. Comprehensive characterization of the bulk composites and the extracted graphene-based powders from composites, as well as the results of an independent parallel plate experiment, revealed that the GO in the sheared melt has a higher reduction degree than that in the quiescent melt within identical processing temperatures and times. On the basis of our results, we hypothesize that the more intense reduction of GO in the sheared melts relative to the quiescent melts is associated with the enhanced π–π stacking and the possible radical reaction between polymers and GO sheets.