http://nopr.niscair.res.in/handle/123456789/2622 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/2658 Title: A simple way to predict electric spark sensitivity of nitramines <br/> <br/>Authors: Keshavarz, M H; Pouretedal, H R; Semnani, A <br/> <br/>Abstract: This work presents a new simple method for predicting electric spark sensitivity of nitramine energetic compounds. This method is based on the calculated detonation velocity at maximum nominal density (theoretical maximum density) and then corrected for some nitramines which have some specific molecular structure. The predicted electric spark sensitivity by new method are compared with calculated results on the basis of quantum mechanical computations for 17 nitramines so that the root mean square (rms) deviations from experiment for new and complicated quantum mechanical methods are 1.23 and 4.02 J, respectively. The new model is also used for two new nitamine explosives TNAZ [1,3,3-trinitroazatidine] and TEX [4,10-dinitro-2,6,8,10-tetraoxa-4,10-diazaisowurtzitane] in which predicted results are close to measured values. <br/> <br/>Page(s): 505-509 Fri, 28 Nov 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2657 Title: Thermal, spectroscopic and electrical transport properties of processable poly(aniline-co-alkylaniline) copolymers <br/> <br/>Authors: Saini, Parveen; Bhandari, Hema; Choudhary, Veena; Dhawan, S K <br/> <br/>Abstract: Aniline has been copolymerized in the presence of substituted anilines as comonomers to prepare conducting copolymers of poly(aniline-co-alkylaniline) type, via the chemical oxidative polymerization route. Their thermal stabilities and conductivities are slightly less than pure polyaniline but processabilities have been improved significantly. These copolymers exhibit improved solubility in organic solvents like 1-methyl-2-pyrrolidone (NMP), dimethyl sulpohxide (DMSO), and dimethyl formamide (DMF). Conduction mechanism has been found to be 3-D VRH in case of pure HCl-doped polyaniline and 1-D VRH for copolymers. Coating of these polymers on insulating surfaces can be used for ESD protection and corrosion prevention of iron and mild steel under hostile conditions. <br/> <br/>Page(s): 497-504 Fri, 28 Nov 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2656 Title: Optical, electrical and structural studies of nickel-cobalt oxide nanoparticles <br/> <br/>Authors: Tharayil, Nisha J; Raveendran, R; Vaidyan, Alexander Varghese; Chithra, P G <br/> <br/>Abstract: Nanoparticles of nickel-cobalt oxide are prepared by chemical co-precipitation method. The particle size is determined from X-ray diffraction studies and TEM image. The surface morphology is revealed by SEM image. The effect of sintering on the particle size is analyzed. The FTIR studies have been used to confirm the formation of metal oxide. The characteristic stretching and bending frequencies of the sample is analyzed. The absorption spectra of the material in the UV-Vis–NIR range are recorded. An absorption band is observed to occur at 350 nm and another one around 650 nm. From the analysis of absorption spectra, the nickel-cobalt oxide (sintered at 500°C, 700°C and 900°C) are found to have direct band gaps ranging from 1.827 to 1.61 eV. Electrons are highly localized in nanoparticles and interaction between these localized states give rise to the observed band gap. The effect of temperature and frequency on the dielectric behaviour and ac electrical conductivity have been studied for nanosized samples of nickel cobalt spinel oxide prepared by chemical co-precipitation method. The dielectric permittivity of nanosized nickel cobalt spinel oxide sample is evaluated from the observed capacitance values in the frequency range 100 kHz-5 MHz and in the temperature range of 300-403 K. It is seen that with decreasing frequency, the dielectric constant increases much more obviously than that of conventional materials. As the temperature increases more and more dipoles are oriented resulting in an increase in the values of dipole moment. Space charge polarization and rotation direction polarization play a crucial role in the dielectric behaviour of this nanosized material. Further from the permittivity studies ac conductivity is evaluated. <br/> <br/>Page(s): 489-496 Fri, 28 Nov 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2655 Title: Effect of environment on the mechanical properties of fly ash-jute-polymer composite <br/> <br/>Authors: Acharya, S K; Mishra, P; Mishra, S C <br/> <br/>Abstract: The present investigation is aimed at processing a composite using fly ash, jute with epoxy (binder) and to study its weathering behaviour on mechanical properties such as flexural strength. The fracture surfaces of the specimen are examined under scanning electron microscope. From the study, it appears that fiber pullout is the predominant mode of failure. The cracking of the fiber structure is avoided due to adherence of fly ash particles which indicates the increase in strength of interfacial bonding. It can be concluded that this composite can be successfully used as a structural material in household and automobile application and as a low cost building material. <br/> <br/>Page(s): 483-488 Fri, 28 Nov 2008 22:58:59 GMT