Influence of solvent properties on the electrical response of poly(vinylidene fluoride)/NaY composites

Different solvents were used for the preparation of poly(vinylidene fluoride), PVDF, and NaY zeolite composites by solvent casting and melt crystallization. Solvents like N,N-dimethylformamide (DMF), dimethylsulphoxide (DMSO) and triethyl phosphate (TEP) were chosen as they present different dielectric constants and can be encapsulated in the porous structure of NaY zeolite introduced in the PVDF/zeolite composites. The solvent molecules encapsulated induce variations in the dielectric response of the composite films according to the solvent dielectric constant. In this way, the solvent with the higher dielectric constant, DMSO, results in the composite with higher dielectric constant, while the opposite happens with TEP. The solvent molecules modify the distribution of intra zeolite cations increasing the dielectric constant of the composite. The zeolite also contribute to the increase of the d.c. conductivity, which is characterized by a double regime indicated by a breaking voltage, which value decreases when the dielectric constant of the solvent increases.