Electrical conductivity of polyvinylidene fluoride nanocomposites filled with carbon nanotubes and nanofibers

Polyvinylidene fluoride (PVDF) nanocomposites filled with low loading levels of pristine multiwalled carbon nanotubes (MWNTs), carboxyl functionalized MWNTs (FMWNTs) and vapor grown carbon nanofibers (VGCNFs) were prepared by a versatile coagulation method. The ac electrical conductivity of the composites was investigated in the frequency range 40-12 MHz. The frequency dependence of the conductivity can can be described the universal dynamic response. A dc plateau followed by the frequency dependence regime was observed. The dc conductivity obeyed a percolation scaling law. The percolation thresholds of VGCNF-PVDF, MWNT-PVDF and FMWNT-PVDF were determined to be 1.46, 1.0 and 0.98 vol%, respectively. Moreover, percolative nanocomposites exhibited non-linear I-V characteristics, demonstrating the presence of tunneling conduction.