Electret behavior of electrospun PVdF-based polymers

This paper deals with the electromechanical response of electrospun mats made of PVdF-TrFE, which is generally ascribed to piezoelectric effect. The electric signals detected, on the contrary, do not show a typical piezoelectric response. This could be due to the porous structure of the electrospun specimens or to a more complex behavior. For this purpose, high speed camera pictures, space charge measurements and atomic force microscopy were performed. These measurements showed that the charge stored in the material bulk and on the surface due to electrospinning process and triboelectric effect, respectively, provide an electret behavior to the specimen, which may overwhelm the piezoelectric effect of the polarized β-phase, if any.