Investigation on the effect of γ-irradiation on the dielectric and piezoelectric properties of stretchable PVDF/Fe-ZnO nanocomposites for self-powering devices.

Stretchable films of PVDF nanocomposites containing iron doped ZnO (Fe-ZnO) nanoflowers are fabricated following simple solution mixing and γ-irradiation treatment. An increase in β-phase crystallinity is noticed for the PVDF/Fe-ZnO nanocomposite when compared to PVDF/ZnO at the same filler concentration. Specifically, at 1 wt%, the relative crystallinity of the composite containing Fe-ZnO calculated from FTIR is 48.1%, while for ZnO, it is 40.9%. A dielectric constant of 96 is reached for PVDF/Fe-ZnO at 2 wt%, in addition to a peak to peak output piezoelectric voltage of 2.4 V. This is several times higher than that observed for PVDF/ZnO nanocomposites and those fabricated without γ-irradiation (1.1 V). Piezoelectric voltage generation is also observed during the stretching, bending and rolling vibrational movements of the sample, indicating its possible use in flexible electronic devices. The observed superior performance of the PVDF/Fe-ZnO system is attributed to the influence of the star like morphology and dispersion of Fe-ZnO, and the enhanced filler-polymer interaction and crosslink formation by the γ-irradiation process. It is demonstrated that such a system can be applicable in manufacturing piezoelectric nanogenerators for various industrial applications including robotic parts, biomedical devices etc.