Synthesis and Characterization of Polyvinylidene-fluoride (PVDF) Nanofiber for Application as Piezoelectric Force Sensor

Abstract

Abstract In the present study, PVDF nanofibers containing primarily β-phase have been synthesized by electrospinning process. For electrospinning, a number of PVDF laden precursors were prepared varying the composition of solvents (60%-80% DMF) as well as wt% of PVDF (10wt%, 12wt%, and 15 wt% PVDF). The operating parameters for electrospinning were also varied for achieving optimal size and morphology of the PVDF nanofibers. The synthesized fibers were characterized by Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-Ray Diffraction (XRD) and differential scanning calorimetry (DSC). PVDF with the solvent ratio of 7:3 offers beads free, thin nanofibers in comparison with other compositions. The presence of crystalline β-phase was successfully confirmed by the XRD analysis. An exothermic peak was also observed by the DSC analysis at the temperature of 70°C. PVDF nanofiber based piezoelectric force sensors were constructed and their performances were tested by applying calibrated load using a universal mechanical testing (UTM) machine and observing the resulting signal in an oscilloscope. A clear correlation was observed between the peak voltage detected by the PVDF force sensor and the applied load. The study revealed the piezoelectric property for force sensing tends to maximize (maximum current -14 µA, initial sensitivity-160 mV/kPa) around 12 wt% of PVDF due to presence of β+γ phase in sample.