Local Electrical Characterization of PVDF Textile Filament

International audienceThe piezoelectric behavior of poly(vinylidene fluoride), PVDF, has been known for several decades and is clearly related to its crystalline phases. Many works made on films or fibers have focused on the characterization of the phase transitions during various PVDF processing and on its electromechanical activity by combining several techniques. Piezo-force microscopy (PFM) is an interesting tool to underline the crystalline forms and piezoelectricity efficiency of PVDF at the local scale. However, this technique is little used on samples in the form of fibers and in this case, it is most often nanofibers. In this work, two conventional PVDF textile filaments, with different weak draw ratio, are produced and analyzed by FTIR, XRD, and PFM. We demonstrate that the PFM analysis can be relevant for specimens presenting low signals during other characterizations. Therefore, the local piezo-/ferroelectricity into the fiber is highlighted underlining the existence of the polar phases of PVDF. Then, the effective piezoelectric coefficient d33 of PVDF fiber drawn with a ratio of 1.5 is estimated at 12 pm/V