Faculty Publications
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Item Comparative Studies on Crystalline and Amorphous Vinylidene Fluoride Based Fibrous Polymer Electrolytes for Sodium-Ion Batteries(Springer Singapore, 2020) Janakiraman, S.; Khalifa, M.; Biswal, R.; Ghosh, S.; Anandhan, S.; Adyam, A.In the present work, electrospun poly (vinylidene fluoride) (PVDF) and poly (vinylidene fluoride-co hexafluropropylene) (P(VdF-co-HFP)) fibrous membranes have been compared. Porous homo and copolymer fiber-based membranes with an interconnected structure, high porosity, large electrolyte uptake were prepared by an electrospinning route. The effect of crystallinity in terms of X-ray diffraction (XRD) was investigated for the fibrous polymer membranes (FPMs). The surface morphology of the FPMs is evaluated by field emission scanning electronmicroscopy (FESEM). The FPMswere soaked in 1MNaClO4-ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1, vol%) solution to form fibrous polymer electrolytes (FPEs). The ionic conductivity of copolymer showed 1.126 mS cm−1 under ambient temperature (at 28 °C) higher than the homopolymer (0.79 mS cm−1) because of HFP unit. The electrochemical stability window of the copolymer membrane also enhanced and stable up to 4.9 V versus Na+/Na suitable for high voltage sodium rechargeable batteries. When tested with Na066Fe0.5Mn05O2 as cathode and Na metal as an anode, the cycle performance significantly improved for the copolymer. © Springer Nature Singapore Pte Ltd. 2021.Item Sol-gel electrospinning of diverse ceramic nanofibers and their potential applications(Elsevier, 2020) George, G.; Senthil, T.; Luo, Z.; Anandhan, S.Ceramics are composed of both metallic and nonmetallic elements and commonly exist as compounds of oxides, nitrides, and carbides. Two decades back, the use of ceramics was limited to a handful of applications, as in household utilities and some industrial uses. In the era of nanotechnology, the definition and application of materials are altered, especially in the case of ceramics. By the development of various fabrication techniques of nanostructured ceramics, the scope of ceramic materials is radically transformed, making them the most beneficial among the materials ever designed for several critical applications. The fabrication of ceramic nanostructures is challenging from an industrial point of view since many fabrication techniques need sophisticated instrumentation, skilled personnel, purity of chemicals, specificity of the medium, controlled atmosphere, etc. and are anticipated for lab-scale production. The electrospinning process is an exception, which can address all the former problems associated with other fabrication techniques. This chapter covers the electrospun ceramic nanofibers such as oxides, carbides, nitrides, sulfides, etc. from various precursors and their application in the field of biomedical engineering, filtration, energy, electronics, sensor, catalysis, etc. and their peculiar properties, such as photoluminescence, thermoelectric, piezoelectric, and magnetic. Nevertheless, the application of ceramic nanofibers, far more than what is discussed here, and advanced studies are essential to explore the applications of ceramic nanofibers in numerous untouched areas where conventional materials can be replaced. © 2021 Elsevier Ltd All rights reserved.Item 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.Item Parametric study of manufacturing ultrafine polybenzimidazole fibers by electrospinning(Springer, 2012) Anandhan, S.; Ponprapakaran, K.; Senthil, T.; George, G.Polybenzimidazole (PBI), a high performance polymer, was synthesized from 3,3?-diaminobenzidine (DAB) and isophthalic acid (IPA) through polycondensation. The chemical structure of PBI was confirmed by Fourier transform infrared spectroscopy. Thermal characterization of PBI was done by thermogravimetry and differential scanning calorimetry. PBI nanofibers were fabricated by electrospinning of N, N-dimethyl acetamide solutions of PBI of different solution concentrations, at different voltages. The effects of solution and process parameters (namely, solution concentration and DC voltage) on morphology and average diameter of electrospun PBI fibers were investigated. The electrospun ultrafine fibers' diameter and morphology were characterized by using scanning electron microscopy. Nanofibers were obtained only from PBI solutions of concentrations 12 and 14 % (w/v). At concentrations of 8, 10, and 16 %, fibers could not be obtained. The process parameters were optimized by using the statistical tool, factorial or two-way ANOVA (analysis of variance), DOE (design of experiments) and the results indicate that the applied voltage and the interaction of voltage and solution concentration are influential in determining the diameter and morphology of the electrospun ultrathin PBI fibers. Electrospun PBI fibers, as small as 56 nm, could be successfully produced by using the right combination of solution concentration and spinning voltage. © 2012 Central Institute of Plastics Engineering & Technology.Item Solution electrospinning of styrene-acrylonitrile random copolymer from dimethyl sulfoxide(Springer India sanjiv.goswami@springer.co.in, 2013) Senthil, T.; Anandhan, S.Electrospinning is an efficient and versatile technique for the fabrication of ultrafine fibers having diameters ranging from nano to sub-micron level for various potential applications. In this study, we have investigated the influence of process and solution parameters, such as solution concentration, flow rate and applied voltage, on the morphology of electrospun poly(styrene-co-acrylonitrile) (SAN) fibers. Morphology and average diameter (Davg.) of the electrospun SAN fibers were characterized by scanning electron microscopy (SEM). The SEM results reveal that concentration, applied voltage and flow rate of solution are strongly associated with formation of defects, such as beads, in the fibers. Ultrafine SAN fibers with Davg. in the range of 96-872 nm were obtained by controlling the experimental parameters. The Davg. of electrospun fibers increased with increasing solution concentration, applied voltage and flow rate. Also, the Davg. exhibits a power law relationship with the solution concentration. © 2013 Central Institute of Plastics Engineering & Technology.Item Chemical-resistant Ultrafine Poly(styrene-co-acrylonitrile) Fibers by Electrospinning: Process Optimization by Design of Experiment(2013) Senthil, T.; George, G.; Anandhan, S.The effects of solution and processing parameters on the morphology and diameter of electrospun poly(styrene-co-acrylonitrile) fibers were investigated by design of experiment. Morphology of the electrospun fiber mats were investigated by scanning electron microscopy. With increasing solution concentration, fiber morphology changed from that of a spindle-like beaded one to smooth, and the average fiber diameter increased from 96 to 876 nm. Average fiber diameter gradually increased with applied voltage; however, fiber morphology was only slightly influenced by flow rate. Regression analysis results reveal that solution concentration has the most significant impact on the average and standard deviation of fiber diameter. © 2013 Copyright Taylor and Francis Group, LLC.Item Structural characterization of nano-crystalline Co3O4 ultra-fine fibers obtained by sol-gel electrospinning(2013) George, G.; Anandhan, S.In this paper, we report the obtention of ultrafine fibers of cobalt oxide (Co3O4) by combining electrospinning method with high-temperature calcinations from the precursor sol of poly(2-ethyl-2- oxazoline) (PEtOx)/cobalt acetate tetrahydrate [Co(CH3COO) 2·4H2O] in water. The optimum electrospinning conditions for obtaining precursor composite nanofibers from PEtOx/Co(CH 3COO)2·4H2O solution in water, to produce ceramic nanofibers, were studied. The average fiber diameter of the precursor composite fibers measured by scanning electron microscopy (SEM) was approximately 200 nm. Thermogravimetric analysis of PEtOx was performed to estimate the suitable calcination temperature of the precursor fibers. SEM images of the ceramic fibers obtained after calcination revealed the shrinkage in diameter due to complete degradation of the polymer and Co(CH 3COO)2·4H2O. Fourier transform infrared spectroscopy was used to ensure the complete pyrolysis of polymer during calcinations of the composite fibers. Crystalline properties of the ceramic fibers were studied by X-ray diffraction and high resolution transmission electron microscopy. The ceramic fibers are polycrystalline with an average grain size of ?40 nm obtained at a calcination temperature of 773 K. It was observed that the grain sizes increased as the calcination temperature was increased, due to self assembly mechanism. © 2013 Springer Science+Business Media New York.Item Structure-property relationship of sol-gel electrospun ZnO nanofibers developed for ammonia gas sensing(Academic Press Inc. apjcs@harcourt.com, 2014) Senthil, T.; Anandhan, S.Zinc oxide (ZnO) based nanomaterials have been used in various gas sensors due to the wide band gap (3.37. eV), large exciton binding energy and high mobility of charge carriers of ZnO. In this work, nanocrystalline ZnO nanofiber mats were synthesized through combined sol-gel electrospinning techniques followed by calcination, in which poly(styrene- co-acrylonitrile) and zinc acetate were used as the binder and precursor, respectively. Average diameter of the ZnO nanofibers decreased from 400 to 60. nm, while their grain size and crystallinity were enhanced by increasing the calcination temperature. Morphology and structure of the ZnO nanofiber mats were characterized by high resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. ZnO nanofiber mats were found to be superhydrophilic (contact angle was close to 0°) by contact angle measurements. The sensitivity of these ZnO nanofibers in detecting gaseous ammonia was tested using an indigenous set up. Due to their high surface area and superhydrophility, these ZnO nanofiber mats were highly sensitive in sensing gaseous ammonia and the sensitivity of these mats increased as a function of their calcination temperatures. © 2014 Elsevier Inc.Item Comparison of structural, spectral and magnetic properties of NiO nanofibers obtained by sol-gel electrospinning from two different polymeric binders(Elsevier Ltd, 2015) George, G.; Anandhan, S.NiO is a p-type semiconductor with wide band gap energy. In this study, nickel oxide nanofibers were fabricated by sol-gel electrospinning followed by high temperature calcination, using two sacrificial polymeric binders. Poly(2-ethyl-2-oxazoline) (PEtOx) in water and styrene-acrylonitrile random copolymer (SAN) in N,N- dimethylformamide (DMF) along with nickel (II) acetate tetrahydrate (NATH), as metal oxide precursor, were the two distinct polymeric systems used in this study. The morphological and structural properties of NiO fibers obtained from the aforementioned systems were compared with each other. The degradation behavior of the sacrificial polymeric binder imparted a significant effect on the properties of the obtained NiO fibers. The grain sizes and the activation energies for grain growth of NiO fibers from two systems were different. The non-stoichiometric NiO fibers obtained from the SAN/NATH system had a better ferromagnetic behavior as compared with that produced from the PEtOx/NATH system. This non-stoichiometry made a difference also in the optical band gap energies of the NiO nanofibers. © 2015 Elsevier Ltd.Item Electrospinning of non-woven poly(styrene-co-acrylonitrile) nanofibrous webs for corrosive chemical filtration: Process evaluation and optimization by Taguchi and multiple regression analyses(Elsevier, 2015) Senthil, T.; Anandhan, S.Nano-fibrous ultra-filtration membranes of poly(styrene- co-acrylonitrile) were produced from n-butanone solution by electrospinning. Effects of governing parameters on morphology and variation in diameter of the electrospun fibers were experimentally investigated by orthogonal experimental design. The process parameters were selected by Taguchi's method. Multiple regression analysis was used to obtain a quantitative relationship between selected electrospinning parameters and average fiber diameter and ANOVA was used to identify the statistically significant parameters and set the optimal level for each parameter. Confirmation experiment revealed a good agreement between the predicted values of the response obtained from optimum level parameters and the observed experimental values. © 2014 Elsevier B.V.