Bandana Rajpoot; Sushil Kumar Singh; Abhishek Kumar; Anuj Jain
Abstract
This study is focused to see reinforcing effects of SiO2 nanoparticles on the mechanical and thermal properties of epoxy resin. For the same, SiO2 nanoparticles up to 8 wt.% were reinforced in epoxy resin and the effect of this reinforcement was seen on fracture toughness, fracture energy and glass transition ...
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This study is focused to see reinforcing effects of SiO2 nanoparticles on the mechanical and thermal properties of epoxy resin. For the same, SiO2 nanoparticles up to 8 wt.% were reinforced in epoxy resin and the effect of this reinforcement was seen on fracture toughness, fracture energy and glass transition temperature. The particles were dispersed ultrasonically in epoxy resin, which gives well dispersion of nano-SiO2 particles. A good dispersion of silica nanoparticles enhances mechanical and thermal properties up to 4 wt.% SiO2. As a result, the value of fracture toughness increases from 1.10 to 2.90 M Pa.m1/2, fracture energy increases from 2.66 to 11.50 kJ/m2 and glass transition temperature increased about 9°C for the epoxy containing 4 wt.% SiO2 nanoparticles. With further particle loading in epoxy reflected decrease in mechanical and thermal properties, which is attributed to the significant increase in clustering of the nanoparticles at higher loading concentrations.
Sudha C. Angadi; Lata S. Manjeshwar; Tejraj M. Aminabhavi
Abstract
Nanocomposite microspheres of chitosan (CS) with magnesium aluminum silicate (MAS) and enteric coated with poly(vinyl acetate phthalate) (PVAP) have been prepared and examined for controlled release (CR) of capecitabine, an anticancer drug. The microspheres have been characterized by X-ray diffraction ...
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Nanocomposite microspheres of chitosan (CS) with magnesium aluminum silicate (MAS) and enteric coated with poly(vinyl acetate phthalate) (PVAP) have been prepared and examined for controlled release (CR) of capecitabine, an anticancer drug. The microspheres have been characterized by X-ray diffraction (XRD) to study the drug distribution, DSC to understand thermal stability and Fourier transform infrared (FTIR) spectroscopy to investigate the chemical interactions as well as to assess the structures of drug-loaded formulations. Surface morphology of the microspheres was investigated by scanning electron microscopy (SEM). The size distribution of the formulated microspheres studied by particle size analyzer was in the range of 303-350 μm, while their encapsulation efficiencies ranged from 50 to 58%. Equilibrium swelling of the microspheres was measured in both pH 1.2 and 7.4 media. In vitro release of capecitabine has shown a dependence on polymer-clay composition, amount of crosslinking agent and extent of enteric coating. The formulations extended the release of drug up to 32 h. The enteric coating with PVAP effectively reduced the burst release of the drug in gastric pH medium. The present method offers promising results for controlled release of short-acting drugs. Copyright © 2018 VBRI Press.
Isha Saini; Annu Sharma; Naveneet Chandak; Sanjeev Aggarwal; Pawan K. Sharma
Abstract
Silver (Ag) nanoparticles play a significant role in nanomaterials science and technology due to many peculiarities. One of the main characteristic of Ag nanoparticles is the occurrence of surface plasmon resonance (SPR) due to the collective oscillation of free electrons in visible region. Due to this ...
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Silver (Ag) nanoparticles play a significant role in nanomaterials science and technology due to many peculiarities. One of the main characteristic of Ag nanoparticles is the occurrence of surface plasmon resonance (SPR) due to the collective oscillation of free electrons in visible region. Due to this distinctive feature Ag nanoparticles have numerous applications such as in catalysis, surface enhanced Raman spectroscopy, photonics, solar cells etc. In the present work, no additional stabilizing agent has been used. The characteristic SPR peak appears at around 405 nm in UV-Visible absorption spectra of PVA-Ag nanocomposite films, thereby confirming the nanocomposite formation. The synthesized nanocomposite films were structurally characterized using fourier transform infrared (FTIR) and Raman spectroscopy. FTIR spectra of PVA-Ag nanocomposite film indicates that PVA matrix is modified by Ag nanoparticles which is in agreement with the results obtained using Raman spectroscopy. TEM as well as FE-SEM micrographs reveal that Ag nanoparticles are mostly spherical in shape. The knoop microhardness number of the nanocomposites was found to increase from 2.4 Kgf/mm2 for PVA to 12.1 kgf/mm2 for PVA-Ag nanocomposite film loaded with 0.062 wt% Ag nanoparticles. Copyright © 2018 VBRI Press.
Agnieszka Ślosarczyk; Paulina Jakubowska
Abstract
In presented article the research on sol-gel synthesis of silica aerogel from cheaper precursor water glass with ambient pressure drying was shown. In addition to strengthen the silica aerogel frame the as-received and oxidized carbon microfibers from coal-tar pitch were used. The presence of carbon ...
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In presented article the research on sol-gel synthesis of silica aerogel from cheaper precursor water glass with ambient pressure drying was shown. In addition to strengthen the silica aerogel frame the as-received and oxidized carbon microfibers from coal-tar pitch were used. The presence of carbon microfibers in silica aerogel does not influence the structural parameters, on the contrary, the carbon microfibers diminish the density and contraction during drying of silica aerogel nanocomposite. Modification of the silica aerogels in a mixture of TMCS/n-hexane in 70°C with concurrent modification of carbon microfibers results in obtaining a durable nanocomposite, up to the temperature of 600°C, characterized by high level of hydrophobicity, which is proved by tests on contact angle. Moreover, the analysis with EDS probe proved, in case of the nanocomposites with carbon microfiber, a lack of sodium, being a remnant of the silica gel synthesis from water glass, which implies a higher level of substrate reaction during the sol-gel synthesis, and results in obtaining better parameters of the silica aerogel. Copyright © 2018 VBRI Press.
Vipin Jain; Anil Kumar; Ajay Dhar
Abstract
Graphene possesses excellent properties such as, high Young’s modulus (1 TPa), high fracture strength (~125 GPa) and extreme thermal conductivity (~5000 W/m/K), therefore, can serve as an ideal reinforcement material for the metal based High Tech structural nanocomposites. In the present work, ...
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Graphene possesses excellent properties such as, high Young’s modulus (1 TPa), high fracture strength (~125 GPa) and extreme thermal conductivity (~5000 W/m/K), therefore, can serve as an ideal reinforcement material for the metal based High Tech structural nanocomposites. In the present work, a novel chemical synthesis method has been adopted for the in-situ synthesis of aluminium-graphene (Al-Gr) nanocomposite powders with varying compositions using graphene oxide (GO) as the precursor. The pure aluminium powder was initially cryomilled to refine the crystallite size. Subsequently, Al-reduced graphene (Al-Gr) nanocomposite powders were synthesized employing different volume proportions of GO (referred as 0.5, 2, 4, and 6 ml) dispersed in deionized water. The synthesized nanocomposite powders were ball milled followed by consolidation using spark plasma sintering under the optimized conditions. The nanocomposite powder as well as SPSed samples were characterized using X-ray diffraction (XRD), Raman Spectroscopy and electron microscopy. Scanning electron microscopy (SEM) studies of nanocomposite powders have depicted wrinkled structure typical of reduced graphene. Raman spectra have shown regular D, G, 2D and D+G bands and a modulated 2D peak having intensity significantly less than the G peak was observed for the nanocomposite powders confirming multilayered graphene is synthesized. The graphene wrinkles were determined in the size of 100 nm or more. Microhardness of SPS sintered nanocomposites is found progressively increased with the increasing content of reduced graphene with up to 58% improvement over pure Al was observed for the maximized GO content depicting potential for energy efficient high strength applications. The synthesized Al-graphene nanocomposites are novel in terms of an innovative, indigenously developed and scalable to bulk synthesis approach based on in-situ chemical synthesis route adopted. Copyright © 2017 VBRI Press.
Hemlata J. Sharma; Megha A. Salorkar; Subhash B. Kondawar
Abstract
Electrospun nanofibers of Polyaniline (PANI)/SnO2 composite based gas sensor for hydrogen (H2) and carbon monoxide (CO) gas were prepared by electrospinning technique. The synthesized material was characterized using UV-Visible, XRD and SEM-EDX analyses. The average diameter of PANI/SnO2 composite was ...
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Electrospun nanofibers of Polyaniline (PANI)/SnO2 composite based gas sensor for hydrogen (H2) and carbon monoxide (CO) gas were prepared by electrospinning technique. The synthesized material was characterized using UV-Visible, XRD and SEM-EDX analyses. The average diameter of PANI/SnO2 composite was found to be high as compared to that of pristine SnO2 nanofibers having 200 nm diameter may be due to micelle formation of PANI on the surface of SnO2 nanofibers.The enhanced sensing properties in the form of sensitivity factor, time taken to response and recovery during exposure and de-exposure of Gas and repeatability were studied. The SnO2/PANI composite nanofibers showed high sensitivity and response to H2 gas compared to CO gas to 0.1% and maximum sensitivity was observed at 35˚C for H2 gas. Fast Response-Recovery Time for 1000-5000 ppm of H2 i.e. less than 30 secs were observed. Due to room temperature operation of the sensor, it is promising for environmental applications. The results indicate that aligned SnO2/PANI composite fibers are promising candidate for fast detection of H2 gas. Copyright © 2017 VBRI Press.
J. Dhanalakshmi; D. Pathinettam Padiyan
Abstract
GdxTi1-xO2 nanocomposites with x=0.00, 0.02, 0.04, 0.06, 0.08 & 0.10 were prepared through sol-gel method. The samples were characterized using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), High resolution scanning electron microscope (HR-SEM), Raman spectroscopy and photoluminescence ...
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GdxTi1-xO2 nanocomposites with x=0.00, 0.02, 0.04, 0.06, 0.08 & 0.10 were prepared through sol-gel method. The samples were characterized using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), High resolution scanning electron microscope (HR-SEM), Raman spectroscopy and photoluminescence spectroscopy (PL). The XRD pattern and Raman spectra confirmed the presence of crystalline nature and phase pure anatase tetragonal system. The average crystallite size of the samples was between 10 to 18 nm. HR-SEM images indicated the formation of spherical like particles of GdxTi1-xO2 nanocomposites. An obvious reduction in particle size of GdxTi1-xO2 nanocomposites were noticed while comparing the SEM images of bare TiO2 and composite samples. Coupling of Gd is responsible for slight blue shift in absorption edge. The presence of oxygen vacancies is confirmed in Raman and PL spectra. These oxygen vacancies potentially trap electrons and restrict the electron-hole recombination and thus improve the photocatalytic reactions.
