Dielectric Behavior and AC Conductivity of PVDF/MWCNT Composites: Role of Interfacial Polarization and Beta-Phase Formation

Abstract

Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer distinguished by its remarkable ferroelectric, piezoelectric, and pyroelectric characteristics, which are most pronounced in its electroactive ?-phase. Embedding multi-walled carbon nanotubes (MWCNTs) within the PVDF matrix gives a viable route to enhance its dielectric, electrical, and thermal characteristics through interfacial polarization, ?-phase induction, and micro-capacitor network formation. In this study, PVDF/MWCNT nanocomposites containing MWCNT concentrations of 0.5, 1, and 2 wt% were made-up using solution casting followed by hot pressing. The dielectric and electrical behaviors were examined within the frequency range of 0.5–10 kHz and temperature range up to 135 °C via impedance spectroscopy. The obtained results revealed that the dielectric constant exhibits an increasing trend with rising temperature as well as higher MWCNT content, reaching a value of approximately 60 at 3 kHz and 135 °C for the 2 wt% composite, primarily due to enhanced interfacial polarization and ?-phase content.

Keywords: PVDF; MWCNT; Nanocomposites; Dielectric properties; Interfacial polarization; AC conductivity; Energy storage