Faculty Publications

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Publications by NITK Faculty

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Author: search.filters.author.Anandhan, S.Subject: search.filters.subject.Energy harvesting

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Now showing 1 - 7 of 7
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    Electrospun PVDF-based composite nanofabrics: An emerging trend toward energy harvesting
    (Elsevier, 2021) Shetty, S.; Anandhan, S.
    Poly(vinylidene fluoride) (PVDF) has gained attention in energy-related applications, due to its ferroelectric, piezoelectric, and pyroelectric properties. PVDF is a semicrystalline fluoropolymer having different phase domains based on its chain conformations. The polar domains contribute to its ferroelectric and piezoelectric characteristics. Electrospinning is a facile nanofabrication technique used to produce ultrafine fibers that self-integrates into functional webs/nanofabrics. This chapter emphasizes the electrospinning/filler route to tune the electroactive properties of PVDF-based composite nanofabrics and their applicabilities toward energy-related systems. The influence of various fillers/additives on the structure, morphology, and electroactive response of PVDF composite nanofabrics, including their incorporation into energy-related systems, is described in detail. Understanding the interplay between the filler and PVDF matrix coupled with electrospinning could contribute toward the fabrication of scalable and practical energy systems. © 2021 Elsevier Inc.
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    Probing the synergism of halloysite nanotubes and electrospinning on crystallinity, polymorphism and piezoelectric performance of poly(vinylidene fluoride)
    (Royal Society of Chemistry, 2016) Khalifa, M.; Mahendran, A.; Anandhan, S.
    Poly(vinylidene fluoride) (PVDF) nanofibers have tremendous potential in nano-sensing and energy scavenging applications. In this study, uniaxially aligned nanofibers were developed from halloysite nanotubes (HNT)/PVDF nanocomposite using electrospinning technique. Incorporation of HNT into PVDF not only reduced the diameter of the electrospun nanofibers, but, also improved their morphology. Fourier transform infrared spectroscopy, wide angle X-ray diffraction and differential scanning calorimetry techniques were used to characterize the crystallinity, polymorphism and polymer-filler interaction in the nanocomposite nanofibers. A force sensor was indigenously designed to study the piezoelectric responses of the nanocomposite nanofibers. At 10 wt% of HNT loading, the sensor produced the highest voltage output, which can be ascribed to its highest ?-phase content. Incorporation of HNT and use of electrospinning synergistically enhanced the ?-phase content and hence the piezoelectric behavior of PVDF. Hence, these nanofibers could be promising and prominent materials in sensor and actuator applications. © The Royal Society of Chemistry.
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    Synergism of Electrospinning and Nano-alumina Trihydrate on the Polymorphism, Crystallinity and Piezoelectric Performance of PVDF Nanofibers
    (Minerals, Metals and Materials Society 184 Thorn Hill Road Warrendale PA 15086, 2018) Khalifa, M.; Deeksha, B.; Mahendran, A.; Anandhan, S.
    Poly(vinlylidene fluoride) (PVDF) is known for its electroactive phases, which can be nucleated by incorporating nanoparticles into PVDF to enhance its piezoelectric performance. In this study, the synergistic effect of electrospinning and nano alumina trihydrate (ATH) filler was used to enhance the electroactive ? phase of PVDF. Electrospun nanofibers of PVDF/ATH nanocomposite (PANCF) were synthesized with different loadings of ATH. The presence of ATH enhances the surface charges of the electrospun droplets, leading to thinner fibers. The highest ?-phase content was found to be 70.1% for PANCF with 10% ATH. The piezoelectric performance of the nanofiber mats was studied using an indigenous setup. The highest voltage output of 840 mV was produced by PANCF with 10% ATH. These nanofibers could be a promising material in the field of sensors, actuators and energy-harvesting applications. © 2018, The Minerals, Metals & Materials Society.
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    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.
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    Cationic surfactant assisted enhancement of dielectric and piezoelectric properties of PVDF nanofibers for energy harvesting application
    (Royal Society of Chemistry, 2021) Ekbote, G.S.; Khalifa, M.; Mahendran, A.; Anandhan, S.
    Poly(vinylidene fluoride) (PVDF) is among the most versatile polymers due to its wide range of properties, including dielectric, piezoelectric and ferroelectric properties. However, more frequently than not a range of processing routes and/or additives have been used to enhance such properties. In this study, PVDF nanofibers were electrospun from PVDF solution that contained tetra-n-butyl ammonium chloride (TBAC) at different loadings (1, 2, 3, and 5 wt%). The effect of TBAC on the morphology, crystallinity, and polymorphism of PVDF was studied using various characterization techniques. Addition of TBAC significantly improved the electroactive ?-phase of PVDF. The highest ?-phase content of 89% was attained at a TBAC loading of 3 wt%. Consequently, the dielectric and piezoelectric properties of the PVDF nanofibers improved significantly. A nanogenerator fabricated using 3 wt% TBAC/PVDF nanofibers exhibited the maximum voltage output of 17.2 V (under 5 N force) and the maximum power density of ?1.4 ?W cm?2(under 3 N force). Improved dielectric and piezoelectric properties of PVDF upon the addition of a small amount of TBAC could be useful for researchers in upbringing the material for flexible electronic devices. © The Royal Society of Chemistry 2021.
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    A study on electroactive PVDF/mica nanosheet composites with an enhanced ?-phase for capacitive and piezoelectric force sensing
    (Royal Society of Chemistry, 2021) Khalifa, M.; Schoeffmann, E.; Lammer, H.; Mahendran, A.R.; Wuzella, G.; Anandhan, S.
    Herein, a multifunctional poly(vinylidene fluoride) (PVDF)/mica nanosheet composite (PMNC) thin film was developed for preparing a capacitive and piezoelectric force sensor. A high electroactive ?-phase content (89%) of PVDF was achieved through a facile rapid cooling process of PMNC films. The crystallinity of PVDF decreased upon the addition of mica nanosheets, while the dielectric constant increased significantly (?300%). The capacitance-based PMNC pressure sensor was found to be sensitive to the applied pressure. On the other hand, piezoelectric voltages of 18 V (single layer) and 32 V (multi-layer) were generated for PMNCs loaded with 1% mica nanosheets. Furthermore, a PMNC based nanogenerator generated a power density of 8.8 ?W cm?2and showed excellent durability (>60?000 cycles). High flexibility, lightweight and skin-friendly PMNCs could be a potential material in applications such as energy harvesting, energy storage, actuators, and self-powered and smart wearable electronic devices. © The Royal Society of Chemistry 2021.
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    A Facile Strategy to Achieve High Piezoelectric Performance in Electrospun Poly(Vinylidene Fluoride) Non-woven Nanofabrics
    (Korean Institute of Electrical and Electronic Material Engineers, 2024) Khalifa, M.; Kumar, M.; Subramanian, G.; Anandhan, S.
    Poly(vinylidene fluoride) (PVDF) with its piezoelectric characteristics holds the potential to be the promising candidate in microdevices, sensors and actuators. In this study, a facile strategy was adopted to augment the electroactive β-phase of electrospun PVDF non-woven nanofabric. Electrospun PVDF non-woven fabric was mechanically stretched at different strain rates. SEM images revealed that upon stretching the non-woven fabric, the fibers tend to orient along the stretching direction. The fibers from the necked region were characterized to understand effect of stretching on the polymorphism, crystallinity and piezoelectric performance. The β-phase content of PVDF increased upon increasing the strain rate, while the degree of crystallinity decreased slightly. The highest β-phase content of 79% was achieved for electrospun PVDF non-woven fabric stretched at 10 mm/min. Further, the piezoelectric performance of the stretched nanofabric was evaluated to assess its electroactive characteristics. The piezoelectric performance of electrospun PVDF fabric was studied by imparting the pressure/load by one-finger tapping, hand pressure and dropping weight. The highest output voltage and current of 8.4 V and 249 nA, respectively were obtained from the electrospun PVDF non-woven stretched at 10 mm/min, which is almost 8 times higher than that of the unstretched PVDF non-woven. Given the flexibility, lightweight with good piezoelectric performance these electrospun PVDF non-woven fabrics could be a potential material for energy harvesting and self-powered nano-electronic devices. Graphical Abstract: (Figure presented.) © The Korean Institute of Electrical and Electronic Material Engineers 2023.