Effects of nano-sized BaTiO3 on microstructural, thermal, mechanical and piezoelectric behavior of electrospun PVDF/BaTiO3 nanocomposite mats

Polyvinylidene fluoride (PVDF) is a good candidate for use in wearable electronics due to its flexibility, ease of processing, and ability to generate electrical charge in response to applied mechanical stress. In this work, low density polyvinylidene fluoride (PVDF) nanocomposites containing nano-sized BaTiO3 with cubic symmetry were fabricated by electrospinning process, aiming to generate dominant electroactive beta polar phase. The influence of nano-sized filler content on the microstructure, total degree of crystallinity, beta phase content, and piezoelectric properties of the electrospun PVDF/BaTiO3 nanocomposites was systematically studied. The crystallinity and the thermal stability were evaluated using differential scanning calorimetry (DSC), x-ray diffraction (XRD) and thermogravimetric analysis (TGA). The content of evolved piezoactive beta phase was determined by FTIR spectroscopy. It was shown that the electrospinning process is primarily responsible for very high content (up to 99.4%) of the developed piezoactive crystalline phase. High degree of crystallinity (up to 56.4%) was determined in PVDF/BaTiO3 nanocomposites, confirming the nucleation ability of the nanofiller. Maximum tensile strength of 55.5 MPa (127% higher than PVDF nanofiber mat) and maximum d33 coefficient of 18 pC N-1 were determined for the nanofiber mat containing 20 wt% BaTiO3. We believe that this work provides an important insight into the nanoparticles' distribution and their agglomeration (SEM and TEM analyses) influence on the final properties of PVDF/BaTiO3 webs, generated via electrospinning.