Investigations on spin coated poly(vinylidene fluoride) flexible films

摘要

PVDF is a widely studied polymer due to its piezoelectric, ferroelectric and pyroelectric properties. Flexible PVDF films were prepared by spin coating technique which were in α phase. Polar β phase has been obtained by mechanically stretching the film. Investigations of the films was done using XRD, which indicated amorphous nature in α phase giving rise to much broader background scattering and the spectra contained sharp peaks due to crystallites in β phase. Values of the peaks obtained from FTIR studies indicate the transformation of the films from α to β phase. Micro structural study was done using SEM. Granular structure was observed in α phase and fibres in β phase. EDX indicated the presence of the elements of PVDF. The UV-Vis spectra of the developed film has been co-related to optical band gap using Tauc’s expression. The Dielectric permittivity has almost remained a constant in the frequency range of 100 Hz to 1 MHz. The stretched film was exposed to high electric field wherein the molecular dipoles get oriented in the direction of the field and net polarization is formed. Piezoelectric properties were measured using piezometer. These results may be exploited in the development of sensors.