Morphological evaluation and phase behavior of PVDF/PEO blends in the presence of graphene nanoplatelets through rheological measurements

In this study, graphene nanoplatelets (GNPs) were incorporated into poly(vinylidene fluoride) (PVDF), poly(ethylene oxide) (PEO), and PVDF/PEO blends using solution casting method in order to achieve binary and ternary polymer nanocomposites. The focus of the work is on the compatibilizing effects of the GNPs on partially miscible PVDF/PEO blends. X-ray diffraction method, rheological measurements, scanning electron microscopy (SEM), and atomic force microscopy observations enabled us to track the dispersion state and localization of the graphene nanosheets in the nanocomposites. The results exhibited that the nanoplatelets were preferentially distributed through the PVDF phase and/or at the interface of the PVDF/PEO phases. Evaluation of the wetting parameter for the PVDF/PEO/GNPs nanocomposite also verified better affinity of the selected nanofiller with the PVDF component. Extend of the miscibility in the nanocomposites was studied by a well-known rheological method. A tangible increment in binodal (T-b) and spinodal (T-s) decomposition temperatures by addition of a very low content of the GNPs (0.5 wt %) revealed well-defined compatibilization effects of the graphene on this binary polymer blend. SEM images at different temperatures confirmed the rheologically determined liquid-liquid phase diagram. (c) 2019 Wiley Periodicals, Inc.