Enhanced Electroactive Beta Phase In Three Phase Pvdf/Caco3/Nanoclay Composites: Effect Of Micro-Caco3 And Uniaxial Stretching

In this study, electroactive polar phase transformation and crystallinity of poly(vinylidene fluoride) (PVDF)-based composites, such as PVDF/CaCO3/nanoclay, is explored as a function of micro-CaCO3 fraction and draw ratio (R) of uniaxial stretching. Composites including PVDF/clay, PVDF/CaCO3 and most importantly PVDF/CaCO3/clay with varying fraction of micro-CaCO3 were extruded into homogenous and flexible cast films. Characterization via Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry (DSC) confirmed the presence of beta phase in all the composites incorporated with micro-CaCO3 and nanoclay either individually (i. e., PVDF/CaCO3 and PVDF/clay films, respectively) or together (i. e., PVDF/CaCO3/nanoclay composites). Interestingly, a gradual but significant improvement in this electroactive phase (beta phase) was obtained with successive increment in CaCO3 content into a fixed composition of PVDF and nanoclay (PVDF/CaCO3/clay composites). Further increment in b phase content was obtained via uniaxial stretching to different draw ratios and at a temperature of 90 degrees C, where for PVDF/CaCO3/clay (especially, 100-35-3 and 100-40-3) samples almost no a phase was observed irrespective of R. Conversely, the crystallinity of melt extruded samples decreased gradually all the way with CaCO3 concentration in PVDF/CaCO3/clay composites compared to the neat PVDF while increased gradually with increasing draw ratio. (C) 2017 Wiley Periodicals, Inc.