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61.
Nonisothermal crystallization kinetics of carbon nanotubes containing segmented polyurethane elastomer 下载免费PDF全文
Y.N. Gupta T. Bhave A. Chakraborty A.K. Pandey R.B. Sharma D.K. Setua 《Polymer Engineering and Science》2016,56(11):1248-1258
Nanocomposites of the segmented polyurethane (SPU) elastomer with different concentrations of multiwall carbon nanotubes (MWCNTs) have been prepared. Scanning electron microscopy has been used to visualize the surface morphology and distribution of the nanotubes inside the matrix. Differential scanning calorimetry has been utilized to investigate the effects of MWCNTs on the crystallization characteristics of the SPU by collecting data at four cooling rates namely 5, 10, 15, and 20°C/min in the temperature range between 200°C to ambient. The results reveal that MWCNTs act as effective nucleating agent for crystallization of the hard segment of SPU and advance the onset and peak temperatures of crystallization by 38 and 23°C, respectively. The associated enthalpy and extent of crystallization are also increased by 34%. Different crystallization kinetic parameters have been calculated using both modified Avrami and combined Ozawa‐Avrami models to suggest a three dimensional growth of crystallization of SPU and its nanocomposites. The activation energy has been calculated using Kissinger method, which indicates that activation energy decreases with increasing concentration of MWCNTs. The calorimetric results have further been correlated with thermomechanical analysis and glass transition temperature of the nanocomposites corresponding to soft segment is found to increase by 20°C. POLYM. ENG. SCI., 56:1248–1258, 2016. © 2016 Society of Plastics Engineers 相似文献
62.
Devi Neena Patel Sanjay K. S. Kumar Pradeep Singh Archana Thakur Nandita Lata Jeevan Pandey Deepak Thakur Vikram Chand Duni 《Catalysis Letters》2022,152(4):944-953
Catalysis Letters - In this study, Rhodococcus pyridinivorans cells containing hyperactive acyltransferase was immobilized on various macromolecules based-polymeric matrices and used to improve... 相似文献
63.
Gupta Vidyadhar Awasthi Himanshi Kumar Nitish Pandey Amit Kumar Gupta Abhinav 《SILICON》2022,14(6):2989-2997
Silicon - This present article interprets the analytical models of central channel potential, the threshold voltage, and subthreshold current for Graded-Doped Junctionless-Gate-All-Around... 相似文献
64.
Das Satish K. Nanda Umakanta Biswal Sudhansu M. Pandey Chandan Kumar Giri Lalat Indu 《SILICON》2022,14(6):2965-2973
Silicon - Short channel effects (SCEs) along with mobility degradation has a great impact on CMOS technology below 100 nm. These effects can be overcome by using gate and channel... 相似文献
65.
Silicon - In this paper, we have done performance evaluation of different Gate All Around (GAA) FET device structures using gate-oxide stacking and spacers of different materials including dual and... 相似文献
66.
S. L. Agrawal Markandey Singh Mridula Tripathi Mrigank Mauli Dwivedi Kamlesh Pandey 《Journal of Materials Science》2009,44(22):6060-6068
Present work deals with findings on dielectric relaxation behaviour and a.c. conduction in a SiO2-doped polymer nanocomposite electrolyte system, namely, [(100 − x)PEO + xSiO2]:yNH4SCN. The formation of nanocomposite has been ascertained by XRD measurements. The effect of salt and filler (SiO2) on conductivity response of PEO-based nanocomposite polymer electrolyte has been investigated by impedance spectroscopy.
The variation of dielectric permittivity, dielectric loss and modulus spectra with frequency and temperature was carried out
from impedance spectroscopy data. The a.c. conductivity seems to follow the universal power law. 相似文献
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Variation of ultrasonic attenuation and velocities with temperature have been evaluated in the temperature range 5-50 K due to electron-phonon interaction mechanism in transition metals vanadium, niobium and tantalum for longitudinal and shear waves. For this evaluation, we have also computed the second order elastic constants using Morse potential. Behaviour of acoustical phonons in these bcc metals is different from other normal metals, intermetallics, semimetallics and alloys. Some characteristic features of these materials connected to ultrasonic parameters are discussed. 相似文献
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Biswaranjan Dhal Hrudayanath Thatoi Nigamananda Das Bansi Dhar Pandey 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(11):1471-1479
BACKGROUND: The reduction of highly mobile and toxic hexavalent chromium by bacterial strains is considered to be a viable alternative to reduce Cr(VI) contamination, in soils and water bodies, emanating from the overburden dumps of chromite ores and mine drainage. The present study reports the isolation of Cr(VI) resistant bacterial strains from an Indian chromite mine soil and their potential use in reduction of hexavalent chromium. RESULTS: Among the isolates, a bacterial strain (CSB‐4) was identified as Bacillus sp. based on standard biochemical tests and partial 16SrRNA gene sequencing, which was tolerant to as high as 2000 mg L?1 Cr(VI) concentration. The strain was capable of reducing Cr(VI) to Cr(III) in different growth media. Under the optimized conditions pH ~7.0, 100 mg L?1 Cr(VI), 35 °C temperature and stirring speed 100 rpm, CSB‐4 reduced more than 90% of Cr(VI) in 144 h. The time course reduction data fitted well an exponential rate equation yielding rate constants in the range 3.22 × 10?2 to 6.5 × 10?3 h?1 for Cr(VI) concentration of 10–500 mg L?1. The activation energy derived from temperature dependence rate constants between 25 and 35 °C was found to be 99 kJ mol?1. The characterization of reduced product associated with bacterial cells by SEM‐EDS, FT‐IR and XRD was also reported. CONCLUSION: Reasonably high tolerance and reduction ability of indigenous Bacillus sp. (CSB‐4) for Cr(VI) under a wide range of experimental conditions show promise for its possible use in reclamation of chromite ore mine areas including soils and water bodies. Copyright © 2010 Society of Chemical Industry 相似文献