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Polyvinylidene fluoride (PVDF)-based copolymers with tetrafluoroethylene (P(VDF-TFE)), trifluoroethylene (P(VDF-TrFE)) or hexafluoropropylene (P(VDF-HFP)) are of strong interest due to the underlying fundamental mechanisms and the potential ferro-, pyro- and piezo-electrical applications. Their flexibility and their adaptability to various shapes are advantageous in comparison to inorganic ferroelectrics. Here, we study the influence of stretching temperature on the crystalline phases and the dielectric properties in P(VDF-TFE) films by means of Dielectric Relaxation Spectroscopy (DRS), Fourier-Transform InfraRed spectroscopy (FTIR), Wide-Angle X-ray Diffraction (WAXD), Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Especially, the effect of stretching and the influence of the temperature of stretching on the mid-temperature ($T_{mid})$ transition are studied in detail. The results show that stretching has a similar effect as that on PVDF, and we observe an increase in the fraction of ferroelectric $\beta$-phase with a simultaneous increment in both melting point ($T_m)$ and crystallinity (${\chi }_c)$ of the copolymer. While an increase in the stretching temperature does not have a profound impact on the amount of ferroelectric phase, the stability of the ferroelectric phase seems to improve — as seen in the reduction of the Full Width at Half Maximum (FWHM) of the WAXD peaks in both parallel and perpendicular directions to the molecular chain axis. The observation is also supported by the reduction of dissipation losses with an increase in stretching temperature — as seen in DRS measurements. Finally, both stretching itself and the temperature of stretching affect the various molecular processes taking place in the temperature range of the $T_{mid}$ transition.

Titanium dioxide is added into calcium phosphate bio-glass (CPG) to have crystalline phases of titanium phosphoric (TiP₂O₇) and calcium phosphoric (CaP₂O₇) on its surfaces. The bio-glass synthesis with the addition of titanium dioxide herein is denoted as TCPG. To elucidate their surface morphologies, both specimens of CPG and TCPG were immersed in Hanks' solution for two days before soaking in the mixed solutions of (NH₄)₂HPO₄ and Ca(NO₃)₂ at 70°. Crystalline layers of titanium phosphoric were observed on the surfaces of TCPG from immersing in Hanks' solution. After which calcium pyrophosphate appeared on the second step of soaking process from the calcium ion contained solutions. Due to the absence of crystalline phases on the surfaces of CPG specimen, it can be deduced that the addition of titania (TiO₂) causes the hydroxyapatite formation on the surface of bio-glass.