Poly(vinylidene fluoride) (PVDF) displays ferroelectric, piezoelectric and pyroelectric behavior and it is widely used in high-tech applications including sensors, transducers, energy harvesting devices and actuators. The crystallization of this polymer into highly polar  phase is desirable but is hard to achieve without applying specific thermo-mechanical treatments. Indeed, fabrication processes directly affect PVDF molecular chain conformation, inducing distinct polymorphs. In this paper, we present the fabrication of PVDF/BaTiO3 composite foams by thermally induced phase separation method (TIPS). Different compositions are tested and characterized. The crystallinity, and in particular the development of electroactive  crystal phase is monitored by FTIR, DSC and XRD measurements. Dielectric properties are also evaluated. It turns out that TIPS is a straightforward method that clearly promotes the spontaneous growth of the  phase in PVDF and its composite foams, without the need to apply additional treatments, and also significantly improves the degree of crystallinity. BaTiO3 content gives additional value to the development of  phase and total crystallinity of the systems. The low permittivity values (between 2 and 3), combined with the cellular morphology makes these materials suitable as lightweight components of microelectronic circuits.

This paper deals with the optimization of the piezoelectric performances of nanofibrous membranes. Both ceramic and polymeric piezoelectric nanofibers are manufactured via electrospinning and polarized in order to align the ferroelectric domains and enhance the piezoelectric response of the mats. By investigating the electrical properties of the embedding mediums where the nanofibers were immerged during the polarization, it is possible to identify a proper configuration that maximize the dipoles alignment. The measured piezoelectric responses of the produced nanofibrous mats result comparable with commercial stiff piezoelectric samples ones.

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This paper deals with the polarization process of piezoelectric nanofibrous mats of PVdF-TrFE by using a corona discharge process. With respect to traditional contact poling this process reduces the electrical breakdown risk which could easily occur when a highly porous mat is placed between two solid electrodes. Different set-up configurations were investigated by varying the applied voltage and the distance between the needle and the sample. The polarized nanofibers show a piezoelectric strain coefficients (d33) comparable with the values of a commercial stiff film.

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