Polyvinylidene fluoride
(PVDF)-expanded graphite (ExGr)
nanocomposites
have been prepared by solution blending and melt processing methods.
In the presence of polyvinylpyrrolidone (PVP), enhanced dispersion
of graphite nanosheets (GNSs) in the PVDF matrix, as suggested by
field emission scanning electron microscopy analysis, results in very
low electrical percolation threshold (0.3 wt % ExGr). X-ray diffraction,
Fourier transform infrared spectroscopy, and differential scanning
calorimetry (DSC) analyses confirm the coexistence of electroactive
gamma and nonpolar alpha phases. Wrapping of PVP chains around GNSs
reduces the crystallinity in PVDF-ExGr nanocomposites in comparison
to that in neat PVDF films, as evidenced by DSC analysis. Thermogravimetric
analysis confirms enhanced thermal stability of PVDF-ExGr nanocomposites
above 500 °C mainly attributed to the PVP-assisted dispersion
of GNSs. The water contact angle of solution-blended PVDF-ExGr nanocomposite
films increases with and without PVP in comparison to that of the
neat PVDF film. Compression-molded PVDF-ExGr nanocomposites also exhibit
electroactive gamma and nonpolar alpha phases of PVDF with reduction
in electrical conductivity compared to solvent-cast films.