Strain sensing performance of poly (vinylidene fluoride) - Onium salt composite sensor to mechanical vibration and impact loading

Piezoelectric polymer Poly (vinylidene fluoride) (PVDF) is extensively used as sensor and actuator devices because of their excellent piezoelectric and pyroelectric properties. The melting point of PVDF, however is relatively low and the service temperature of PVDF is up to 100oC. This restricts the use of PVDF in high temperature applications. This can be improved by adding appropriate fillers to the PVDF. In the present study, a composite of PVDF-Onium salt has been developed and characterized to improve the thermal efficiency of PVDF for high temperature applications. Poly (vinylidene fluoride)-Onium salt composite films have been developed using the solvent cast method and characterized for structural, surface and electrical properties to investigate the presence of β-phase (required for sensor applications) through X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimeter, Raman and Infrared spectra, and dielectric properties. The melting point of PVDF-Onium salt composite was found to be higher (175°C) as compared to the PVDF polymer alone (168.2°C) which has been discussed in detail. The PVDF-Onium salt composite sensors were further tested for dynamic strain sensing application for the first time. The performance of these sensors was evaluated by recording the vibration modes of the cantilever beam and resulting from impact loading.