Crystallinity and morphology of barium titanate filled poly(vinylidene fluoride) nanocomposites

In this study, crystallization behavior and micromorphology of barium titanate (BaTiO₃, or BT) filled poly(vinylidene fluoride) (PVDF) nanocomposites were investigated based on Fourier-transform infrared spectroscopy (FTIR), polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). BT/PVDF nanocomposite films with different concentrations of BT nanoparticles were prepared by solution casting method. The results revealed that the electrical conductivity and Seebeck coefficient of PVDF were improved by the incorporation BT nanoparticles. When 2 wt % of BT was loaded into the PVDF matrix, it mediated the β-phase crystallization in PVDF. Furthermore, the β-phase crystals could be transformed into α-phase after the samples were isothermally crystallized at 155 °C for 20 min. The results of DSC and POM suggest that BT nanoparticles could act as nucleation agents, promoting the crystallization activity of PVDF in a nonisothermal crystallization process. The crystal phase is influential to the electrical properties of PVDF, therefore the findings of this study are useful for the development of new applications based on BT/PVDF nanocomposites, such as high-performance thermoelectric devices or systems.