The addition of nanoclay in the polypropylene matrix has many applications in the field of automotive, packaging and aeronautical industry. Nanocomposites of polypropylene with nanoclay phr (part per hundred of resin) of 2.5, 5.0, 7.5 and 10 are prepared using melt mixing in twin-screw extruder and injection molding. The dispersion of nanoclay in the polypropylene matrix played a significant role in the preparation of nanocomposites. The freeze-fractured microstructures of the 5 phr of nanoclay composites shows better dispersion of clay particles in the polypropylene matrix. Tensile testing is performed to quantify the strength with respect to nanoclay phr in the nanocomposites. Stress strain behaviors during the tensile testing along with critical examining using field emission scanning electron microscope of the fracture surface have evolved that phr value around 5 provide maximum strength. In addition to this, surface roughness of these nanocomposites also indicate that the nanocomposites formed by 5 phr nanoclay give better surface finish. The wear behavior of nanocomposites is investigated using pin-on-disc tribo-tester at different loads (10, 20 and 30 N) and sliding speeds (0.5, 1.5 and 2.5 m/s). A response surface methodology based model is developed to explore the impact of nanoclay phr along with load and sliding speed on the wear behavior of these nanocomposites. Response surface methodology is a statistical technique in which the interaction among process variables is studies. It uses a sequence of design experiments to get an optimal response. It was found that 4.19 phr provides to be optimal value of nanoclay content exhibiting better wear resistance. Present study of composites with nanoclay reinforcement in polypropylene matrix concludes that phr value ranging around 4 to 5 gives best results.
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Copper oxide is a compound that has been considered significant owing to its many advantages such as easy availability of copper in huge quantity, its non-toxic nature and the good electrical and optical properties. It is p-type with bandgap range of 1.21-1.51 eV and has potential of absorption of solar spectrum. In this work, sol-gel chemistry is explored to deposit CuO using cupric chloride dihydrate (CuCl 2 · 2H 2 O) with 5, 10 and 15% concentration of EDTA (capping agent) using low-cost dip-coating and annealed at 400°C. The bandgap of the CuO films was found to be in the range of 1.3-1.8 eV, which is comparable with the reported values and also suggests quantum shift in these nanostructures. These investigations suggest suitability of these layers as absorber for photovoltaic applications. SEM investigation suggests the uniform growth of layers by dip-coating techniques. Capping also appears to control the grain growth as observed by electron microscopy. Sol-gel dipcoating technique is presented in this study for deposition of flat layers. ★ Contribution to the topical issue "Materials for Energy harvesting, conversion and storage (Icome 2017)", edited
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Copper oxide is a semiconductor that has been studied for several reasons such as the natural abundance of starting material copper (Cu); the easiness of production by Cu oxidation; their non-toxic nature and the reasonably good electrical and optical properties. Copper oxide is well-known as cuprite oxide. The cuprite is p-type semiconductors having band gap energy of 1.21 to 1.51 eV. As a p-type semiconductor, conduction arises from the presence of holes in the valence band (VB) due to doping/annealing. CuO is attractive as a selective solar absorber since it has high solar absorbency and a low thermal emittance. CuO is very promising candidate for solar cell applications as it is a suitable material for photovoltaic energy conversion. It has been demonstrated that the dip technique can be used to deposit CuO films in a simple manner using metallic chlorides (CuCl2.2H2O) as a starting material. Copper oxide films are prepared using a methanolic solution of cupric chloride (CuCl2.2H2O) at three baking temperatures. We made three samples, after heating which convert in black colour. XRD data confirm that the films are of CuO phases at a particular temperature. The optical band gap of the CuO films calculated from optical absorption measurements is 1.90 eV which is quite comparable with the reported value. Dip technique is a very simple and low-cost method, which requires no sophisticated specialized setup. Coating of the substrate of a large surface area can be easily obtained by this technique compared to that in physical evaporation techniques and spray pyrolysis. Another advantage of the dip technique is that it is very easy to coat both sides of the substrate instead of only one and to deposit otherwise inaccessible surfaces. This method is well suited for applying coating on the inner and outer surfaces of tubes of various diameters and shapes. The main advantage of the dip coating method lies in the fact that it is possible to deposit a variety of layers having good homogeneity and mechanical and chemical stability with a very simple setup. In this paper the CuO thin films preparation by dip coating method and their characterization will be presented.
ZnO is widely used as a functional material because it has a wide and direct band gap, large excitons binding energy, and excellent chemical and thermal stability. ZnO is a semiconductor material which is widely used as transparent electrodes in solar cells, chemical and gas sensors and light emitting diodes, due to its unique electrical and optical properties. Zinc oxide (ZnO) thin films were deposited on glass substrate by dip coating technique. The effects of sol aging time on the deposition of ZnO films were studied by using the field emission scanning electron microscopy (FE-SEM) and optical transmission techniques. Thin films of ZnO were prepared on glass substrate and annealed at 300 C, 350 C and 400 C. The increase in sol aging time resulted in a gradual improvement in crystallinity. Effect of sol aging on optical transparency is quite obvious through increased transmission with prolonged sol aging time. Interestingly, 72-168 h sol aging time was found to be optimal to achieve smooth surface morphology, good crystallinity and high optical transmittance which were attributed to an ideal stability of solution. The UV-Vis transmittance spectrum of synthesized sample suggests the optical band gap value of 3.2 eV. Dip coating technique create ZnO films with potential for application as transparent electrodes in optoelectronic devices such as solar cell.
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