Formation of poly(vinylidene fluoride) crystalline phases from tetrahydrofuran/N, N-dimethylformamide mixed solvent

The effects of the tetrahydrofuran (THF)/N, N-dimethylformamide (DMF) mixture with various mass ratios of each component on the crystalline phase formation and crystallization behavior in the PVDF film by solution casting was investigated. Poly(vinylidene fluoride) (PVDF) resin was dissolved in the THF/ DMF mixture with different mass ratio at 50°C. The solubility of the PVDF was improved by an increase of DMF content in the mixture of solvents because of the reinforced disruption of the intermolecular polymer bonds. The films were peeled off from the glass substrate at room temperature after the solvents evaporated. The melting behavior of the films was measured with a Perkin-Elmer DSC-7C differential scanning calorimeter. The mixed solvent at a 5/5 ratio resulted in the clear spherulitic structure with a diameter of about 3 μm on the surface of the film.