Structural and electrical response of poly(vinylidene fluoride-co-chlorotrifluoroethylene) copolymer free- standing films

Abstract

Poly(vinylidene fluoride) (PVDF) based polymers were studied as potential dielectric candidates for polymer film capacitors. The present work focused on the structural and electrical responses of PVDF homopolymer and P(VDF-CTFE) copolymers (CTFE, chlorotrifluoroethylene). The solvent casting technique was used for the fabrication of free-standing polymer films. PVDF and P(VDF-CTFE) copolymer films with different CTFE content were cast under different processing conditions. The structural response of these semicrystalline polymer films showed the existence of crystalline phases and changes in crystallinity depending upon the preparation conditions and CTFE content. The electrical responses of PVDF and P(VDF-CTFE) copolymers were investigated under the application of low and high electric fields. For the dielectric study, temperature-dependent dielectric measurements at different frequencies were assessed. Dielectric relaxation in the vicinity of the glass transition temperature was observed along with quantification of activation energies. The effect of CTFE content is also presented. Features such as interface polarization was observed in the high temperature regime. Furthermore, room temperature polarization versus electric field loops of PVDF and P(VDF-CTFE) copolymers were measured at frequency values of 400 and 10 Hz. All PVDF and P(VDF-CTFE) copolymers at low frequency showed lossy capacitor behavior which was further investigated by measuring polarization versus electric field loop over a wide range of frequencies, i.e. 0.1-400 Hz. Polarization values of PVDF and P(VDF-CTFE) copolymer films with different CTFE content were compared on the bases of local dipole moments. (c) 2022 Society of Industrial Chemistry.