Preparation methods of PVDF film with electroactive phase by solution method

Poly (vinylidene fluoride) (PVDF) films with electroactive phases were prepared by simple feasible solution crystallization method. The influences of various precursor solution concentrations, different stirring times and hot pressing process on the formation of electroactive crystal phase structures in PVDF were studied. The X-ray diffraction(XRD) and Fourier transform infrared spectroscopy (FTIR) were used to determine the crystal structure and analyze the formation mechanism of the electroactive phases in PVDF. The results indicate that the different precursor solution concentrations and different processing times have a great influence on the formation of electroactive phases in PVDF. It is easier to form β phase when the solution concentrations range from 7% to 10% and processing times between 2 hours and 3 hours. By using FTIR techniques, a maximum content of 81.3% for β phase is calculated in the situation that solution concentration is 7% and processing time is 2 hours. Hot pressing process plays an important role in the change of crystal structure, and this γ phase in PVDF films will transform into more dense β phase after hot-press process.