Browsing by Author "George, G."

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A comparative study on the physico-chemical properties of sol-gel electrospun cobalt oxide nanofibres from two different polymeric binders
(Royal Society of Chemistry, 2015) George, G.; Anandhan, S.
In this study, two different sacrificial polymeric binders, namely poly(2-ethyl-2-oxazoline) (PEtOx) and poly(styrene-co-acrylonitrile) (SAN) along with cobalt acetate tetrahydrate (CATH), as the metal oxide precursor, were used for the fabrication of Co3O4 nanofibres through sol-gel electrospinning. It was observed that the degradation behaviour and physical properties of SAN and PEtOx influenced the structure, morphology and spectral properties of Co3O4 nanofibres, as the properties of the nanofibres obtained from the aforementioned systems were compared with each other. The grain size, shape and the activation energies for grain growth of Co3O4 nanofibres obtained from these two polymeric systems were different. This difference in grain size and shape caused a difference in the optical band gap energies and the magnetic properties of the Co3O4 nanofibres. This study reveals that one can tailor the characteristics of cobalt oxide nanofibres by an appropriate selection of polymeric binders for sol-gel electrospinning. © The Royal Society of Chemistry.
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.
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.
A comparative study on the physico-chemical properties of sol-gel electrospun cobalt oxide nanofibres from two different polymeric binders
(2015) George, G.; Anandhan, S.
In this study, two different sacrificial polymeric binders, namely poly(2-ethyl-2-oxazoline) (PEtOx) and poly(styrene-co-acrylonitrile) (SAN) along with cobalt acetate tetrahydrate (CATH), as the metal oxide precursor, were used for the fabrication of Co3O4 nanofibres through sol-gel electrospinning. It was observed that the degradation behaviour and physical properties of SAN and PEtOx influenced the structure, morphology and spectral properties of Co3O4 nanofibres, as the properties of the nanofibres obtained from the aforementioned systems were compared with each other. The grain size, shape and the activation energies for grain growth of Co3O4 nanofibres obtained from these two polymeric systems were different. This difference in grain size and shape caused a difference in the optical band gap energies and the magnetic properties of the Co3O4 nanofibres. This study reveals that one can tailor the characteristics of cobalt oxide nanofibres by an appropriate selection of polymeric binders for sol-gel electrospinning. The Royal Society of Chemistry.
Comparison of structural, spectral and magnetic properties of NiO nanofibers obtained by sol-gel electrospinning from two different polymeric binders
(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.
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.
Dispersion analysis of nanofillers and its relationship to the properties of the nanocomposites
(Elsevier Ltd, 2021) George, G.; Dev, A.P.; Asok, N.N.; Anoop, M.S.; Anandhan, S.
The dispersion and distribution characteristics of the reinforcements are the key reasons that influence the mechanical properties of the nanocomposites. In this paper, the dispersion and distribution analysis of nanofillers in a representative polymer is performed and the results are correlated to the crystalline and mechanical properties of the nanocomposite. The nanocomposite used in the present study is ElvaloyÂ®4924 (EVACO)/halloysite nanotubes (HNTs) composite. The dispersion of halloysite nanotubes in the EVACO matrix is recorded as aluminum elemental maps obtained from energy dispersive spectroscopy (EDS). The dispersion and distribution of fillers in the composite are quantified using an image processing technique and it is correlated to the crystalline and tensile properties of the composites. The better dispersion and distribution of HNTs at 1wt.% filler loading resulted in a remarkable improvement in the crystallinity of the composite, which is measured by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The tensile strength was highest for composites loaded with 1 wt.% filler, and the strength decayed as the loading was further increased. Agglomeration of halloysite nanotubes and polymer-filler debonding was the major reason behind the reduction in tensile strength with filler loading, as observed in the scanning electron micrographs of the fractured surfaces. Â© 2021 Elsevier Ltd. All rights reserved.
Effect of nanofillers on the crystalline and mechanical properties of EVACO polymer nanocomposites
(Elsevier Ltd, 2021) George, G.; Hareendran, H.; Kumar, T.M.A.; Joshy, S.; Sanju, A.C.; Anandhan, S.
In this work, the effect of different fillers on the crystalline and mechanical properties of the poly(ethylene-co-vinyl acetate-co-carbon monoxide) (EVACO) terpolymer composite is studied systematically. Alumina trihydrate nanoparticles (nano-ATH), halloysite nanotubes (HNTs), and the multiwalled carbon nanotubes (MWCNTs) are the representative fillers used in the present study. The surface of MWCNTs are decorated using carbonyl, however, nano-ATH and HNTs are used without any surface treatment. The mechanical properties of the composites are evaluated using a tensile test and the improvement in the mechanical properties can be correlated to the improvement in the crystallinity in the composite. The presence of nanofillers in the EVACO matrix significantly influenced the crystallinity, which was determined by X-ray diffraction. The fractography studies reveal the presence of agglomerates at high filler loading results in the subsequent reduction in the tensile properties. Interestingly, the MWCNTs at very low filler loading significantly enhances the tensile properties of EVACO. Â© 2021 Elsevier Ltd. All rights reserved.
Electrospinning: From Fundamentals to Applications
(CRC Press, 2016) Senthil, T.; George, G.; Srinivasan, A.
Electrospinning is not only a unique and fascinating process for the production of polymeric nanobers with diameters ranging from 3 nm to 20 µm, but also the simplest and inexpensive technique to fabricate ultrane continuous polymeric bers. Electrospinning is also known as electrostatic spinning and electrospraying. In the last few years, electrospinning has become popular among academic researchers and industries as it overcomes the various processing diculties in the other nanober-forming techniques. Some of the other techniques for the production of polymer nanobers are drawing, template synthesis, phase separation, and self-assembly (Table 5.1). While electrospinning can produce nanobers, its conventional counterparts, such as melt spinning, dry spinning, gel spinning, and wet spinning, can only produce microbers (Figure 5.2) (Gibson et al. 2001). Almost all the straight chain homopolymeric materials have been actively investigated for developing nanobers by electrospinning. Meanwhile, various FIGURE 5.1 Electrospun nanobers have high surface area. (Reprinted from Colloids Surf., A, 187-188, Gibson, P., Gibson, H.S., and Rivin, D., Transport Properties of Porous Membranes Based on Electrospun Nanobers, 469-481. Copyright 2001, with permission from Elsevier.) semicrystalline and amorphous polymers, natural and synthetic biopolymers, polymer blends, and block copolymers can also be converted into nanobers via the electrospinning technique. © 2017 by Taylor and Francis Group, LLC.
Electrospun nickel oxide nanofiber webs for thermistor applications
(2014) George, G.; Anandhan, S.
[No abstract available]
Electrospun nickel oxide nanofiber webs for thermistor applications
(Springer India sanjiv.goswami@springer.co.in, 2014) George, G.; Anandhan, S.
[No abstract available]
Glass fiber-supported NiO nanofiber webs for reduction of CO and hydrocarbon emissions from diesel engine exhaust
(2014) George, G.; Anandhan, S.
In this study, nickel acetate tetrahydrate (NACTH)/poly(styrene-co-acrylonitrile) (SAN) sol was used for the fabrication of nanocrystalline NiO nanofibers. An indigenous setup was developed to use these nanofibers for the oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) from diesel engine exhaust. The morphological, compositional, and crystalline properties of the NiO nanofibers obtained after calcination were studied by scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and x-ray diffraction (XRD). Clear evidence of defects in the fibers was observed in ultraviolet-visible-near infrared (UV-Vis-NIR) spectra, Raman spectra, and magnetic property measurements. The NiO nanofiber mats supported by glass fiber mats were efficient in oxidizing CO and HC from diesel engine exhaust, and the maximum efficiency was achieved by using NiO nanofibers with the maximum amount of defects. Copyright Materials Research Society 2014.
Glass fiber-supported NiO nanofiber webs for reduction of CO and hydrocarbon emissions from diesel engine exhaust
(2014) George, G.; Anandhan, S.
In this study, nickel acetate tetrahydrate (NACTH)/poly(styrene-co-acrylonitrile) (SAN) sol was used for the fabrication of nanocrystalline NiO nanofibers. An indigenous setup was developed to use these nanofibers for the oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) from diesel engine exhaust. The morphological, compositional, and crystalline properties of the NiO nanofibers obtained after calcination were studied by scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and x-ray diffraction (XRD). Clear evidence of defects in the fibers was observed in ultraviolet-visible-near infrared (UV-Vis-NIR) spectra, Raman spectra, and magnetic property measurements. The NiO nanofiber mats supported by glass fiber mats were efficient in oxidizing CO and HC from diesel engine exhaust, and the maximum efficiency was achieved by using NiO nanofibers with the maximum amount of defects. Copyright Materials Research Society 2014.
Glass fiber-supported NiO nanofiber webs for reduction of CO and hydrocarbon emissions from diesel engine exhaust
(Cambridge University Press, 2014) George, G.; Anandhan, S.
In this study, nickel acetate tetrahydrate (NACTH)/poly(styrene-co-acrylonitrile) (SAN) sol was used for the fabrication of nanocrystalline NiO nanofibers. An indigenous setup was developed to use these nanofibers for the oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) from diesel engine exhaust. The morphological, compositional, and crystalline properties of the NiO nanofibers obtained after calcination were studied by scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and x-ray diffraction (XRD). Clear evidence of defects in the fibers was observed in ultraviolet-visible-near infrared (UV-Vis-NIR) spectra, Raman spectra, and magnetic property measurements. The NiO nanofiber mats supported by glass fiber mats were efficient in oxidizing CO and HC from diesel engine exhaust, and the maximum efficiency was achieved by using NiO nanofibers with the maximum amount of defects. © © Materials Research Society 2014.
Glass fiber-supported NiO nanofiber webs for reduction of CO and hydrocarbon emissions from diesel engine exhaust
(Cambridge University Press, 2014) George, G.; Anandhan, S.
In this study, nickel acetate tetrahydrate (NACTH)/poly(styrene-co-acrylonitrile) (SAN) sol was used for the fabrication of nanocrystalline NiO nanofibers. An indigenous setup was developed to use these nanofibers for the oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) from diesel engine exhaust. The morphological, compositional, and crystalline properties of the NiO nanofibers obtained after calcination were studied by scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and x-ray diffraction (XRD). Clear evidence of defects in the fibers was observed in ultraviolet-visible-near infrared (UV-Vis-NIR) spectra, Raman spectra, and magnetic property measurements. The NiO nanofiber mats supported by glass fiber mats were efficient in oxidizing CO and HC from diesel engine exhaust, and the maximum efficiency was achieved by using NiO nanofibers with the maximum amount of defects. © © Materials Research Society 2014.
Influence of multiwalled carbon nanotubes on the structure and properties of poly(ethylene-co-vinyl acetate-co-carbon monoxide) nanocomposites
(John Wiley and Sons Inc, 2021) George, G.; Mahendran, A.R.; SelvaKumar, S.; Anandhan, S.
In this work, composites of poly(ethylene-co-vinyl acetate-co-carbon monoxide) (EVACO)/surface-modified multiwalled carbon nanotubes (m-MWCNTs) were prepared using a solution casting technique. Acid treatment was employed for the surface modification of MWCNTs to improve the compatibility between polar EVACO and MWCNTs. The influences of m-MWCNTs on the crystalline, mechanical, thermal, and electrical properties of EVACO at very low filler loading were systematically evaluated. The presence of m-MWCNTs in the EVACO matrix influenced the crystallinity, and the respective changes were determined and quantified using dynamic scanning calorimetry and X-ray diffraction. The mechanical properties of the composites were improved remarkably by the addition of a minute quantity (0.05, 0.1, 0.15, 0.2, and 0.25 wt%) of m-MWCNTs. Additionally, m-MWCNTs in the EVACO matrix improved the thermal stability and electrical properties of EVACO. However, the filler loading is below the threshold loading of the fillers, and there was no drastic improvement in the electrical conductivity of the composite. © 2021 Society of Plastics Engineers.
Influence of nano-aluminum-hydroxide on tribological, mechanical and flammability properties of E-glass fabric/epoxy multi-layered laminates
(2014) Shivamurthy, B.; George, G.; Bhat, K.U.; Anandhan, S.
E-glass fabric/nano aluminum hydroxide (ATH)/epoxy composites were prepared by manual lay-up and compression molding. An image processing tool was used to quantify fineness of dispersion of nano-ATH particles in epoxy. Fourier transform infrared (FTIR) spectroscopy was used to understand the interaction between nano-ATH and epoxy. Mechanical properties, sliding wear resistance and fire retardance of these composites improved upon addition of nano-ATH. The composite containing 0.125 wt% of nano-ATH exhibited optimum mechanical properties and low specific wear rate.
Influence of nano-aluminum-hydroxide on tribological, mechanical and flammability properties of E-glass fabric/epoxy multi-layered laminates
(Huthig GmbH, 2014) Shivamurty, B.; George, G.; Bhat, K.U.; Anandhan, S.
E-glass fabric/nano aluminum hydroxide (ATH)/epoxy composites were prepared by manual lay-up and compression molding. An image processing tool was used to quantify fineness of dispersion of nano-ATH particles in epoxy. Fourier transform infrared (FTIR) spectroscopy was used to understand the interaction between nano-ATH and epoxy. Mechanical properties, sliding wear resistance and fire retardance of these composites improved upon addition of nano-ATH. The composite containing 0.125 wt% of nano-ATH exhibited optimum mechanical properties and low specific wear rate.
Morphological and structural characterisation of sol-gel electrospun Co3O4 nanofibres and their electro-catalytic behaviour
(2015) George, G.; Elias, L.; Hegde, A.C.; Anandhan, S.
Evolution of hydrogen and oxygen are a crucial part of many renewable energy systems. The replacement of the essential and expensive components in such systems can reduce the capital cost and improve the effectiveness of those systems. In this study, Co3O4 nanofibres were fabricated from sol-gel assisted electrospun poly(styrene-co-acrylonitrile)/cobalt acetate tetrahydrate precursor composite fibres. The morphological and compositional features of the Co3O4 nanofibres obtained after calcination of the precursor nanofibers were studied using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results of X-ray diffraction study and Raman spectroscopy revealed that the average grain size of the fibres increased with the calcination temperature. Clear evidence of defects in the fibres was observed in ultraviolet-visible-near infrared and energy dispersive spectroscopic measurements. The electrocatalytic behaviour of Co3O4 nanofibres obtained at different calcination temperatures was studied using them for the water splitting reaction in an alkaline medium. The maximum efficiency in the hydrogen evolution reaction was achieved using the Co3O4 nanofibres obtained at the lowest calcination temperature, which had the highest surface area and the smallest grain size. The Royal Society of Chemistry 2015.
Morphological and structural characterisation of sol-gel electrospun Co3O4 nanofibres and their electro-catalytic behaviour
(Royal Society of Chemistry, 2015) George, G.; Elias, L.; Hegde, A.C.; Anandhan, S.
Evolution of hydrogen and oxygen are a crucial part of many renewable energy systems. The replacement of the essential and expensive components in such systems can reduce the capital cost and improve the effectiveness of those systems. In this study, Co3O4 nanofibres were fabricated from sol-gel assisted electrospun poly(styrene-co-acrylonitrile)/cobalt acetate tetrahydrate precursor composite fibres. The morphological and compositional features of the Co3O4 nanofibres obtained after calcination of the precursor nanofibers were studied using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results of X-ray diffraction study and Raman spectroscopy revealed that the average grain size of the fibres increased with the calcination temperature. Clear evidence of defects in the fibres was observed in ultraviolet-visible-near infrared and energy dispersive spectroscopic measurements. The electrocatalytic behaviour of Co3O4 nanofibres obtained at different calcination temperatures was studied using them for the water splitting reaction in an alkaline medium. The maximum efficiency in the hydrogen evolution reaction was achieved using the Co3O4 nanofibres obtained at the lowest calcination temperature, which had the highest surface area and the smallest grain size. © The Royal Society of Chemistry 2015.