Analysis of Crystalline Phases of Electroactive Forms of a Composite of Polyvinylidene Fluoride and Tetrafluoroethylene Copolymer with Nanographite

The work examines the effect of crystallization conditions of vinylidene fluoride (VDF) and tetrafluoroethylene (TFE) copolymer (F-42) from aprotic solvents (dimethyl sulfoxide (DMSO) and dimethylformamide (DMF)) under isothermal conditions at temperatures of 60, 90, and 150°C on the phase composition of the films. The content of crystalline phases in F-42 films is analyzed using Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray phase analysis. The effect of nanographite fillers on the crystalline phases of the copolymer films is also studied. Nanographite fillers alter the crystalline structure of the polymer piezoelectric films and their piezoelectric properties, forming electroactive β and γ phases with high content during crystallization from 5-wt-% solutions of aprotic solvents. Some analytical features of the crystalline allotrope phase content are identified using these methods. The total content of crystalline electroactive phases in the VDF/TFE copolymer during isothermal crystallization from DMSO and DMF is 96–98%, while the β-phase content is 75–80%.