On the Isothermal Crystallization of PVDF-BaTiO$_{\mathrm{3}}$ Nanocomposites

Polyvinylidene fluoride (PVDF) is an unique polymer with ferroelectric, piezoelectric, and pyroelectric features. Barium titanate is a piezoelectric and ferroelectric ceramic. To enhance the ferroelectric and piezoelectric features, nanocomposites of polyvinylidene fluoride-barium titanate (PVDF-BaTiO$_{\mathrm{3}})$ have been obtained by dispersing BaTiO$_{\mathrm{3}}$ nanoparticles (from Nanostructured {\&} Amorphous Materials Inc.) within PVDF via melt mixing. To achieve an uniform distribution of nanoparticles, the melt mixing consisted of 3 segments (190 ~C and 60 rotations per minute (rpm) for 30 minutes, 210 ~ C and 80 rpm for 15 minutes, and 180 ~C and 6o rpm for 30 minutes. The mixing was set at a relatively high temperature as the melting temperature of PVDF is about 177 $^{\mathrm{o}}$C. Detailed isothermal Differential Scanning Calorimetry (DSC) data have been recorded in order to analyze the effect of BaTiO$_{\mathrm{3}}$ nanoparticles on the crystallization of the polymeric matrix. The DSC data are analyzed within the Avrami approach framework including newer developments (such as Ozawa, and the combined Avrami--Ozawa). An original mathematical framework is suggested. Supplementary Raman studies are discussed.