Development, thermal and dielectric investigations of PVDF-Y₂O₃ polymer nanocomposite films

This work involves preparing PVDF-Y₂O₃ polymer nanocomposites to improve thermal and dielectric properties. X-ray diffraction, SEM, FTIR, TGA and dielectric measurements were applied for these films. The cubic crystal structure of Y₂O₃ appeared in XRD spectra and the average size was 39 nm. The sample with a concentration of 1.0 wt% achieved the highest intensity of the β-phase peak at 20.2°. The surface images of these samples were of high homogeneity as recorded by SEM microscopy. FTIR analysis showed absorption bands correlated with α, β and γ-phase. The percentage in β-phase in the nanocomposite films improved with an increase in the Y₂O₃ ratio from 1.0 to 3.0 wt%, especially at 1.0 wt%. From TGA analyzes, it was confirmed that the thermal stability improved with an increase in the yttrium oxide percentage. All of the nanocomposite films had higher values ​​of ΔS, ΔH and ΔG than the pure PVDF film. The dielectric permittivity and energy density of the nanocomposite films improved, especially at 1.0 wt%. The energy density at 0.1 Hz has the values​​ 1.08 x 10^-3, 2.11 x 10^-3, 1.81 x 10^-3 and 1.75 x 10^-3 J/m³ at the ratios 0.0, 1.0, 2.0 and 3.0 wt% of Y₂O₃. The loss tangent values for these nanocomposite films decreased at low frequencies while increased at higher frequencies as the content of Y₂O₃ increased. A marked improvement in ε_s, ε_∞, Δε, AC and DC conductivity was observed with an increase in Y₂O₃ content.