Dielectric Relaxation Behavior of PVDF Composites with Nanofillers of Different Conductive Nature

PVDF-based nanocomposites with insulating BaTiO3, semiconducting SiC and conducting graphite nanoplatelets (GNPs) and with hybridization of these nanofillers were fabricated by simple solution mixing and compression molding. The electrical properties of such composite materials were characterized using AC impedance spectroscopy with frequencies ranging from 50 to 5x106 Hz. The results showed that the solution mixing process enables homogeneous dispersion of nanofillers in the PVDF matrix. The dielectric constant of the PVDF-based nancomposites was found to increase with nanofiller content, particularly for the composites with SiC and GNP fillers. The addition of conductive fillers was shown to have a strong effect on the dielectric relaxations of PVDF in low frequency region. Furthermore, the modulus formalism can well describe the relaxation phenomenon of the PVDF-based nanocomposites. The reduced activation energy derived from the isothermal relaxations indicates facile reorientation of the PVDF dipoles to applied external frequencies.