http://nopr.niscair.res.in/handle/123456789/481 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/556 Title: Application of polypyrrole as an electromagnetic interference shielder <br/> <br/>Authors: Dandekar, S S; Kelkar, D S <br/> <br/>Abstract: Pyrrole has been polymerized chemically using FeCl₃ as an oxidizing agent on the substrate of nylon-6 film. Electromagnetic interference (EMI) studies are conducted on polypyrrole film (10 x 10 cm size; 35-40 μm thick) which was fabricated into the square shape. The EMI test is conducted in the frequency range 100-10000 MHz as per MIL STD-285. Attenuation values(db) obtained at various frequencies are recorded. The results indicate that the attenuation values are reaching a maximum of about 3 db at 200 and 3000 MHz. EMI shielding effectiveness (EMI SE) has also been found to be a function of thickness of polypyrrole film. The values of EMI SE are calculated and found to be 2.1 db for 0.004 cm thick film of polypyrrole. <br/> <br/>Page(s): 215-216 Wed, 27 Feb 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/553 Title: Dielectric relaxation studies of binary mixtures of ethyl alcohol and N,N-dimethylacetamide in the benzene solution from microwave absorption data <br/> <br/>Authors: Sharma, Vimal; Thakur, Nagesh; Sharma, D R; Rangra, V S; Negi, N S <br/> <br/>Abstract: The dielectric relaxation studies of different molar concentrations of ethanol in the binary mixtures of ethanol and N, N-dimethylacetamide in benzene solutions have been studied at 9.883 GHz by using standard standing microwave techniques and Gopala Krishna’s [Trans Faraday Soc, 33 (1957) 767] single frequency concentration variation method at different temperatures (25, 30, 35 and 40ºC). It is found that dielectric relaxation time varies non-linearly with the variation in molar concentration of ethanol in the whole concentration range of the binary mixture. The solute-solute and solute-solvent types of molecular associations have been proposed. The energy parameters (ΔHε, ΔFε, ΔSε) for the dielectric relaxation process of binary mixtures containing 50% molar concentration of ethanol have been calculated at the respective given temperatures. Comparison has been made with the corresponding energy parameters for viscous flow process. It is found that the dielectric relaxation process can be treated as the rate process like the viscous flow process. <br/> <br/>Page(s): 212-214 Wed, 27 Feb 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/552 Title: Study of viscosity and refractive index of nylon 6,6 and poly(methyl methacrylate) in formic acid <br/> <br/>Authors: Reddy, M Mohan; John, K; Naidu, S Venkata <br/> <br/>Abstract: Polymer blends of nylon 6,6 with poly methyl methacrylate(PMMA) have been prepared by solution blending and their miscibility has been investigated using physical techniques. Viscosity and refractive index for blend solutions at different percentages of the blend composition have been measured at 30ºC. The results are discussed. <br/> <br/>Page(s): 209-211 Wed, 27 Feb 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/550 Title: Electronic structure of chromium-aluminium alloys <br/> <br/>Authors: Verma, S K; Rajput, S S <br/> <br/>Abstract: The electronic structure of Cr-Al alloys has been studied by using the charge self-consistent Korringa-Kohn-Rostoker Coherent Potential Approximation method. Results for density of states are presented and found to be in very good agreement with reflected X-ray photo spectra results. It has been found that half width of density of states band of these alloys increases approximately 5 per cent at 85 atomic percentage of Cr with respect to 95 and 75 percentage of Cr, which explains the change in shape and half width of experimental X-ray photo spectra results. <br/> <br/>Page(s): 204-208 Wed, 27 Feb 2008 22:58:59 GMT