  Nano-graphene /polymer composites can functionas pressure induced
electro-switches, at concentrations around their conductivity percolation
threshold. Close to the critical point, the pressure dependence of the electron
tunneling through the polymer barrier separating nanon-graphenes results from
thecompetition among shorteningof the tunneling length and the increase of the
polymer's polarizability. Such switching behaviorwas recentlyobserved
inpolyvinyl alcohol (PVA) loaded withnano-graphene platelets (NGPs). In this
work, PVA is blended withh alpha-poly(vinylidene fluoride) (PVdF)and NGPs.
Coaxial mechanical stress and electric field render the nano-composite
piezoelectric. We investigate the influence of heterogeneity, thermal
properties, phase transitions and kinetic processes occurring in the polymer
matrix on the macroscopicelectrical conductivity and interfacial polarization
in casted specimens. Furthermore, the effect of electro-activity of PVdF grains
on the electric and thermal properties are comparatively studied. Broadband
Dielectricspectroscopy is employed to resolve and inspect electron transport
and trapping with respect to thermal transitions and kineticprocessestraced via
Differential Scanning Calorimetry. The harmonic electric field applied during a
BDS sweep induces volume modifications of the electro-active PVdF grains,
while, electro-activity of PVdF grains can disturb the internal electric field
that free (or bound) electric. The dc conductivity and dielectric relaxation
was found to exhibit weakdependencies.
