Abstract: The present study aimed to identify the potential of modified nanoreinforcement (multiwalled carbon nanotubes; m-MWCNTs) to attenuate the thermal transport/decomposition/transition and mechanical aspects of three different polymeric matrices. In order to develop strong interfacial interaction between the host matrix and the incorporated nanotubes, 3-aminopropyletrimethoxy silane (APTMS) was used to m-MWCNTs. IR spectra confirmed the silane chemical moiety attachment on the upper surface of the MWCNTs. Conventional elastomeric mixing techniques were adopted to disperse m-MWCNTs within the three polymeric matrices (Acrylonitrile butadiene rubber, Silicone rubber, and Styrene Butadiene rubber) separately. SEM images assured the uniform dispersion of m-MWCNTs within the host polymeric matrices. Experimental evaluation of thermal conductivity revealed the reduction of thermal transport through the developed composite specimens by increasing the host polymer matrix to nanofiller concentration (m-MWCNTs). The utmost insulation effect was perceived in the F-MWCNTs incorporated silicone rubber nanocomposite comparatively. Glass transition/crystallization temperatures of the nanocomposites were lessened however melting temperatures were enhanced by impregnating nanotubes into the host polymeric matrices. Maximum thermal stability improvement due to the addition of m-MWCNTs was observed in the silicone elastomeric nanocomposite as compared to the other two systems. Proper dispersion and compatibility of m-MWCNTs with the polymeric matrices effectively enhanced the ultimate tensile strength (UTS)/elongation at break along hardness of rubber of the nanocomposites. The insulation character of m-MWCNTs/silicone rubber system was found best among the explored nanocomposite formulations.
Abstract: Heavy metals in water have always remained a point of concern for the environmental scientists due to their non biodegradability and toxicity. Adsorption and membrane filtration are the most widely studied and applied processes for the treatment of water. Activated carbons have frequently been used for the removal of heavy metals from water by the process of adsorption. With the development of nanotechnology, nanomaterials are used as the adsorbents in water treatment and have proved effective for the removal of heavy and toxic metals from water. nanocarbon materials, nanometal particles and polymer supported nanoparticles are widely used. A new adsorbent comprising of graphite coated with nanonickel particles was prepared, characterized and used for the removal of heavy and toxic metals from water. nanomaterial was characterized using ICP-AES, FTIR, XRD, and SEM. It was used for the removal of cadmium and copper from water. Kinetics and thermodynamics of adsorption of cadmium and copper on both the materials was investigated and compared. Adsorption isotherm of Langmuir, Freundlich and Dubinin-Radushkevich were also applied to the adsorption data for the adsorption and removal of cadmium and copper. Effect of pH was also studied and it was found that nanomaterial was very effective for the removal of Cd and Cu from acidic solutions. Effect of different acids at different concentration was studied and it was found that nanomaterial remained stable for adsorption while carbon alone deteriorated. Results indicate that developed nanomaterial is a very effective adsorbent for the removal of heavy and toxic metals from water and wastewater.
Abstract: The nano-sized TiO2 is an important material based on its application for solar cells. The low-cost synthesis of nano-sized TiO2 is of high demand for commercial purposes. Synthesis of TiO2 nanoparticles was achieved via the low-temperature Sol-gel method. Surface morphology was confirmed from SEM analysis, which showed that particle size is in the range of nanometer with no aggregation, The XRD results confirm the formation of anatase phase with high crystallinity. Furthermore, as prepared nano-sized TiO2 particles were developed as sol-gel ink which was later deposited by spin coating on glass substrate with controlled spinning speed thereafter structural and optical properties were characterized by UV-vis spectroscopy, electrochemical impedance spectroscopy and DSC-TGA. The low-cost synthesis of TiO2 nanoparticles with highly conductive thin films can be used as a potential material for future dye-sensitized solar cells
Abstract: In the current study, various morphologies of zinc oxide (ZnO) including nanorods, nanoflowers, nanosheets/flakes, nanospherical particles, nanohexagonal sheets, and nanoneedles have been prepared by using single step and two-step hydrothermal processes with optimized parameters such as growth temperature, growth time and compositions of both the seed and growth solutions. Fluorine doped tin oxide (FTO) coated glass was used as the substrate. The prepared morphologies were characterized with the help of scanning electron microscopy (SEM) and the purity of nanostructures was confirmed by elemental analysis (EDX). These nanostructures were used as photo-anode material to fabricate the DSSC using a dye (Rhodamine B) for enhancing the range of solar spectrum that is to be adsorbed. Finally the fabricated solar cells were characterized in terms of their efficiency, gauged by their fill factor. Among different morphologies investigated as photo anode materials; nanosheets/flakes were found to be showing maximum efficiency, with fill factor values around 0.5 due to their larger surface area, better porosity and enhanced capability of light trapping and scattering.
Abstract: The present research work describes the fabrication and interlaminar properties testing of carbon fiber aluminum metal laminates (CARALL). CARALL was fabricated through hand layup process followed by compression molding technique and interlaminar properties were assessed through double cantilever beam (DCB) test short beam and flexural test. Different treatments were performed on the surface of aluminum alloy and parameters were optimized to ensure good adhesion between metal sheet and carbon composite layer. Pull-off adhesion test was performed to gauge the adhesion strength of epoxy resin on aluminum alloy sheet. Effect of Multi-wall carbon nanotubes (MWCNTs) was also investigated on the interlaminar properties of CARALL. Treated surface of aluminum alloy sheet was examined under Optical and Field Emission Scanning Electron Microscopy (FE-SEM). Porous surface was evident on aluminum sample due to surface treatment which contributes towards better adhesion between epoxy resin and metal surface through mechanical interlocking and diffusion mechanism. FE-SEM and stereo microscopy was also performed on fractured DCB samples and underlying fracture mechanism was discussed. Test results demonstrated that addition of MWCNTs deteriorated the interlaminar properties of CARALL by weakening the interface between treated aluminum surface and carbon composite.
Abstract: In this study graphene coatings were deposited on mild steel substrate using feasible and environmental friendly method. The successful synthesis of graphite oxide was carried by the modified Hummer’s method. Graphene oxide (GO) coatings were developed from GO/water suspension using electrophoretic deposition (EPD). The EPD parameters voltage and deposition time were varied to deposit uniform adherent coatings. The coatings were post heat treated at 200 °C in vacuum for 4h to assess the effect on coated samples. GO and GO-EPD coating morphology were characterized using Fourier transform infrared spectroscopy (FTIR), Atomic force microscopy (AFM) and Scanning electron microscopy (SEM). Linear polarization (LPR) and electrochemical impedance spectroscopy (EIS) tests were performed in saline solution to evaluate electrochemical response. Coatings were partially reduced due to removal of oxygen containing functional groups during EPD and post heat treatments. The GO post heat treated coating had better corrosion resistance ~2 times than that of bare mild steel and higher charge transfer resistance.
Abstract: Graphene was incorporated into elastomeric Matrices using dispersion kneader and two roller mixing mill to fabricate ablative nanocomposites used in hyperthermal environment encountered by space vehicle or rocket motor. The addition of graphene in the host matrix has remarkably reduced the backface temperature elevation during the ablation testing of the ablatives. The linear and mass ablation resistances have been diminished while insulation indexes of the nanocomposites have been increased the graphene incorporation into the elastomeric matrix. Thermal stability and heat absorbance capability of the polymer nanocomposites were progressed with increasing the filler to matrix ratio. Thermal conductivity of the ablatives have been conducted according to the ASTM E1225-99 and D5470-03, respectively to execute the effect of graphene concentration on the thermal transport characteristics of the tested specimens. Tensile strength of the nanocomposite specimen was augmented with increasing graphene to polymer ratio. Scanning electron microscopy was used to scrutinize the evenly dispersed graphene in the polymer matrix, polymer pyrolysis, and voids formation in the ablated nanocomposites.
Abstract: The growth of vertically aligned ZnO Nanorods arrays using Zinc Nitrate hexahydrate and Hexamethylene Tetramine (HMTA), by Chemical Bath Deposition on Silicon Wafer was investigated. The growth is conducted under influence of Ethane-1,2-diamine, the amine based enhancer was evaluated based on three different ratios (1:0.5, 1:1, 1:1.5) of enhancer to the precursor (Zinc Nitrate and HMTA). The effect different ratios of enhancers on morphology aspect ratio and crystallinity of the as grown Nanorods were studied under Scanning electron microscope (SEM) and X-ray powder diffraction (XRD). Electrical Properties such as current–voltage characteristics were investigated, its correlation to the morphology and aspect ratio of the Nanorods in the presence of 100μL-500μL of Aromatic Compound Cyclohexane and at different applied voltages.
Abstract: This study investigated the purification and refining method for producing a nanometer size zinc oxide (ZnO) from the low-grade ZnO commercial powder using low cost ammonium carbonate solution as a leaching agent. The atomic absorption spectroscopy results show that the concentration of iron, lead and cadmium can be dramatically reduced by ammonium carbonate leaching and washing. X-ray diffraction (XRD) and scanning electron microscope (SEM) results show that structural properties can improve the degree of the preferential c-axis orientation, grain size, and surface morphology of ZnO by solvent evaporation. All physical and chemical results are of particular significance for the preparation of purified ZnO for device fabrication in photovoltaic industry, functional ZnO coatings, and polymer nanocomposite applications.
Abstract: 2D nanosheets/ nanoparticles based MoS2/TiO2 nanocomposites were prepared in different weight compositions which were further employed to investigate photocatalytic degradation of methylene blue. Anatase TiO2 powder was prepared via sol-gel reflux method using titanium tetraisopropoxide as Ti precursor. MoS2/TiO2 nanocomposites were prepared by in situ addition of exfoliated MoS2 (2D-nanosheets) in different weight ratios of 0.1%, 0.5%, 1%, 2% and 5% in TiO2 sol. Surface morphology, phase analysis, optical properties were studied using SEM, XRD, UV-Vis spectroscopy respectively. SEM results showed that TiO2 nanoparticles were completely adsorbed over the surface of MoS2 sheets as reflux synthesis was employed. Efficient charge carrier separation was achieved which reduced recombination, and hence, enhanced photo-degradation of methylene blue was observed. The hetero-structures showed less operation time in sunlight for photodegradation of methylene blue and a highest rate constant was observed by 2 wt.% loading of MoS2 on TiO2. These composites can also be used commercially as they show promising results.