Electrical Properties of PVDF Based Nanocomposites

Nanocomposites based on polyvinylidene fluoride (PVDF) have been obtained by melt mixing, loading the polymeric matrix with various weight fraction (between 0 {\%} to 40 {\%}) of different fillers (multiwalled carbon nanotubes, carbon nanofibers, and barium titanate). Pellets of nanocomposites have been obtained by hot pressing at about 175 $^{\mathrm{o}}$C. Copper contacts have been deposited on the as obtained pellets and the electrical features have been measured by using the two point technique. PVDF is a semicrystalline ferroelectric and piezoelectric polymer with a glass transition temperature of -35 $^{\mathrm{o}}$C and a melting temperature of about 175 $^{\mathrm{o}}$C. Electrical measurements have been performed in a wide range of frequencies starting from dc to ac (up to about 250 MHz). The dependence of the resistivity and dielectric constant on frequency and temperature (between -50 $^{\mathrm{o}}$C to 150 $^{\mathrm{o}}$C) was investigated in detail. Supplementary DSC, WAXS, and Raman data provided detailed information regarding the effect of fillers on phase transitions (glass, crystallization, and melting) and crystalline composition/structure of these nanocomposites.