Faculty Publications
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Item 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.Item Structure-property relationship of halloysite nanotubes/ethylene-vinyl acetate-carbon monoxide terpolymer nanocomposites(SAGE Publications Ltd info@sagepub.co.uk, 2017) George, G.; SelvaKumar, M.; Mahendran, A.; Anandhan, S.Poly(ethylene-co-vinyl acetate-co-carbon monoxide) (EVACO)/halloysite nanotube (HNT) nanocomposite films were solution cast. Dispersion of HNTs in the matrix was analyzed by elemental mapping and the role of HNTs on crystallizability, flammability and thermal, mechanical, and electrical properties of the polymer was evaluated. The nature of interaction between the EVACO matrix and HNTs was studied using Fourier transform infrared spectroscopy. The highest tensile strength was observed for the composite with 1% filler loading, whereas the highest crystallinity was observed for that with 3% filler loading. The decay in the tensile properties at higher filler loading was due to agglomeration of HNTs and debonding of polymer-filler interface. The electrical volume resistivity of the composites decreased with HNT loading because of the ionic charge transfer. The direct current electrical resistivity study of the composites proves that the addition of HNT can improve the antistatic properties of the polymer. © The Author(s) 2015.Item Durable, efficient, and flexible piezoelectric nanogenerator from electrospun PANi/HNT/PVDF blend nanocomposite(John Wiley and Sons Inc. cs-journals@wiley.com, 2019) Khalifa, M.; Mahendran, A.; Anandhan, S.Currently, there is considerable research focus on portable, lightweight, shock-resistant, and inexpensive wearable devices that are ideally powered by harvesting abundant mechanical or vibration energy, making battery or related wiring superfluous. In this study, piezoelectric nanogenerator was electrospun from PANi (polyaniline)/HNT (halloysite nanotube)/PVDF (poly[vinylidene fluoride]) blend nanocomposite. Polymorphism, crystallinity and morphology of the nanogenerator were explored in detail. HNT and PANi acted as a nucleating agent and conductive filler, respectively in PVDF; their synergism helps improve the piezoelectric performance of PVDF. The piezoelectric performance of the nanogenerator patch was studied under various external mechanical stresses, such as pressure, tapping, and impact. A maximum voltage output of approximately 7.2 V was generated by the nanogenerator under impact. The nanogenerator patch attached to human arm exhibited not only excellent piezoelectric response during arm movements, but, also proved to be flexible, highly sensitive and durable. This nanogenerator could possibly be used in wearable piezoelectric energy conversion application for self-powered devices. POLYM. COMPOS., 40:1663–1675, 2019. © 2018 Society of Plastics Engineers. © 2018 Society of Plastics Engineers