THE EFFECTS OF MOLECULAR AND PROCESSING PARAMETERS ON ENERGY HARVESTING CAPABILITY OF PVDF-BASED NANOGENERATORS

In the research of the alternative vibration sensing systems, the major potential is attributed to piezoelectric materials that can generate the electrical output from the waste vibration sources of the industrial machines. Poly(vinylidene fluoride) (PVDF), mostly in the electroactive beta-phase, is a great option due to its excellent piezoelectric properties and good flexibility. The beta-phase PVDF can be obtained by simple stretching of the alpha-phase PVDF films, and the conditions of this process are well documented. Surprisingly, the implications of molecular parameters of the PVDF have not been addressed yet. This study investigates the effect of the molecular weight (Mw) of the PVDF on the beta-phase development and consequential vibration sensing capabilities after uniaxial stretching. The successful phase transformation was confirmed using FTIR and XRD. In the FTIR spectra, a typical alpha-phase peak at 762 cm(-1) diminished giving rise to the beta-phase peak at 840 cm(-1) after the stretching. The results also showed a remarkable impact of the Mw on d33 coefficient making Mw an important parameter that should not be overlooked in designing the PVDF-based sensing elements. The obtained data are highly important for the optimization of the PVDF-based vibration sensors applicable in the efficient structural and health monitoring nanosystems.