Faculty Publications
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Item Polymorphism, dielectric and piezoelectric response of organo-modified Ni–Co layered double hydroxide nanosheets dispersed electrospun PVDF nanofabrics(Springer, 2019) Shetty, S.; Ekbote, G.S.; Mahendran, A.; Anandhan, S.Poly(vinylidene fluoride) (PVDF) with excellent flexibility and electroactive properties is a promising material for energy harvesting. In this study, organically modified Ni–Co layered double hydroxide (OLDH) was synthesized and the nanosheets of this OLDH were used as filler in electrospun PVDF nanofabrics. Morphology, crystallinity, dielectric, and piezoelectric properties of the electrospun nanofabrics were characterized. Presence of OLDH in PVDF nanofabrics led to enhancement of polar ?-phase in the latter, which was corroborated from the results of Fourier transform infrared spectroscopy and X-ray diffraction. Dielectric constant of the nanofabrics tends to increase with OLDH content, while the corresponding dielectric loss remained low. An indigenously designed nanogenerator from these nanofabrics exhibited a maximum output voltage of 6.9 V and power density of 0.92 ?W/cm2 under human finger tapping mode at 3 wt% loading of OLDH. The synergistic effect of OLDH and electrospinning contributed to the enhancement of the ?-phase content, thereby the piezoelectric response of the composite nanofabrics. The demonstrated nanogenerator could possibly power flexible and portable electronic devices. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Item Development of a new flexible nanogenerator from electrospun nanofabric based on PVDF/talc nanosheet composites(Royal Society of Chemistry, 2020) Shetty, S.; Mahendran, A.R.; Anandhan, S.Herein, a flexible piezoelectric nanogenerator composed of electrospun talc/PVDF [poly(vinylidene fluoride)] nanocomposite fabrics has been developed. These nanocomposite fabrics demonstrated enhanced mechanical and piezoelectric properties compared with pristine PVDF nanofabrics. In particular, nanocomposite fabrics with 0.50 wt% talc yielded 89.6% of polar ?-phase in the PVDF matrix, thereby augmenting its piezoelectric response. X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry conclusively affirmed the promotion of polar ?-phase in the talc/PVDF nanocomposite fabrics. The 0.50 wt% talc/PVDF nanocomposite fabric based nanogenerator produced an open-circuit voltage and power density of 9.1 V and 1.12 ?W cm-2, respectively, under repetitive finger tapping mode (under a load of 3.8 N). Furthermore, the nanogenerator was also subjected to frequency modulated-shaker mode, wherein an output voltage of 8.9 V was produced. Improved flexibility, mechanical robustness, and enhanced piezoelectric responsiveness of this nanogenerator could possibly pave the way for its use in portable self-powered devices. This journal is © 2020 The Royal Society of Chemistry.Item Physico-chemical and piezoelectric characterization of electroactive nanofabrics based on functionalized graphene/talc nanolayers/PVDF for energy harvesting(Springer Science and Business Media B.V., 2021) Shetty, S.; Shanmugharaj, A.M.; Anandhan, S.Poly(vinylidene fluoride) (PVDF) is a versatile polymer, whose dielectric, piezoelectric and ferroelectric properties can be augmented by a range of processing routes and/or additives. We developed a flexible nanogenerator using electrospun PVDF/COOH-functionalized graphene nanosheet (FGNS)/talc nanosheet (TNS) hybrid nanocomposites. TNS loading was fixed at 0.50 wt% while FGNS loading was varied (0.05, 0.10, 0.15, and 0.20 wt %) in these nanofabrics and their structure–property relationship was explored. Incorporation of FGNS led to formation of an electrically conductive network in the polymer matrix aided by TNS and electrospinning. The uniform dispersion of the filler nanosheets led to effective enhancement of the electroactive ?-phase of the PVDF matrix. Crystallinity and polymorphism in these systems were explored by FTIR spectroscopy, X-ray diffraction and differential scanning calorimetry. A nanogenerator made of the nanofabric containing 0.5 wt% of TNS and 0.10 wt% of FGNS was mechanically impacted by pneumatic actuator (operating pressure 0.4 MPa), resulting in an output voltage of 12.9 V and a power density of 1.72 µW/cm2, respectively. The piezoelectric coefficient (d33) of this nanofiber system was 61 pm/V as revealed by piezoelectric force microscopy. These novel nanocomposites could be used in flexible energy-harvesting devices. © 2021, The Polymer Society, Taipei.