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Institution

Vikram Sarabhai Space Centre

FacilityThiruvananthapuram, India
About: Vikram Sarabhai Space Centre is a facility organization based out in Thiruvananthapuram, India. It is known for research contribution in the topics: Aerosol & Ultimate tensile strength. The organization has 2092 authors who have published 3058 publications receiving 47975 citations. The organization is also known as: VSSC.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a tetra functional epoxy resin with imidazole-based curing agents was investigated by differential scanning calorimetry (DSC), and decomposition of the cured compounds was studied by thermogravimetric analysis.
Abstract: Non-isothermal curing kinetics of a tetra functional epoxy resin with imidazole-based curing agents was investigated by differential scanning calorimetry (DSC), and decomposition of the cured compounds was studied by thermogravimetric analysis. N,N,N′,N′-tetraglycidyl-4, 4′diaminodiphenylmethane (TGDDM) was cured with three types of tertiary amine curing agents including 1-methyl imidazole (MI), 2-methyl imidazole (2MI) and 2-ethyl 4-methyl imidazole (EMI). These systems exhibited cure initiation at around 70–90 °C by DSC. 2-methyl imidazole and 2-ethyl 4-methyl imidazole showed two cure initiation profiles, while the 1-substituted counterpart, MI, showed a single cure initiation profile by DSC. The Kissinger equation was applied to calculate the apparent activation energy for epoxy–imidazole cure reactions. The rate constants and the pre-exponential factor were also determined. The activation energy varied from 59 to 65 kJ mol−1 for the systems. The Flynn–Wall–Ozawa iso-conversional approach was used to elucidate the activation energies at different extents of conversion during the cure reactions. The cured systems are found thermally stable up to 250 °C. Decomposition kinetics of cured networks was studied using Kissinger equation and Flynn–Wall–Ozawa iso-conversional approach. The cured resins were analyzed for the glass transition temperature and compared with that of a conventional amine-cured system.

20 citations

Journal ArticleDOI
TL;DR: The particle number, size distributions, and new particle formation (NPF) events were investigated in the South Asian outflow over the southeastern Arabian Sea (SEAS), the northern (NIO) and equatorial Indian Ocean (EIO) during the winter of 2018 based on the extensive measurements of particle number size distributions in size range 10-414nm in the marine atmospheric boundary layer (MABL) as part of the Integrated Campaign for Aerosols, gases, and Radiation Budget (ICARB - 2018) experiment.

20 citations

Journal ArticleDOI
TL;DR: In this paper, an eight-noded quadratic rectangular element is developed in order to study the stability aspects of a layered rectangular composite plate under biaxial loading, which includes the Mindlin-type nonlinear strain-displacement relations.

20 citations

Journal ArticleDOI
TL;DR: In this article, the effect of swift heavy ions on the structural and photoluminescence spectra of plasma-polymerized thin films is investigated, and the results show that ion irradiation of polymers can induce irreversible changes in their structural, electrical, and optical properties.

20 citations

Journal ArticleDOI
TL;DR: In this article, the Larginine nitrate (LAN) hemihydrate has been used to derive equilibrium geometry, vibrational wavenumbers and the first hyperpolarizability of the nonlinear optical (NLO) material.
Abstract: The near infrared Fourier-transform (NIR FT)-Raman and Fourier-transform infrared (FT-IR) spectroscopies supported by HF/6-31G(d) computations have been employed to derive equilibrium geometry, vibrational wavenumbers and the first hyperpolarizability of the nonlinear optical (NLO) material, L-arginine nitrate (LAN) hemihydrate. The reasonable NLO efficiency, predicted for the first time in this novel compound, has been confirmed by Kurtz–Perry powder second harmonic generation (SHG) experiments. The changes in the atomic charge distribution among different groups due to the presence of strong electronegative atoms and the shrinking of NO bonds of nitrate anion and CN bonds of guanidyl group have been analyzed. The splitting of the carboxylate stretching modes, blue shifting of methine vibrations and the electronic effects such as backdonation and induction on the methylene hydrogen atoms have also been examined in detail. The intense low wavenumber H-bond Raman vibrations due to electron–phonon coupling and nonbonded interactions in making the LAN molecule NLO active have been discussed based on the vibrational spectral features. The natural bond orbital (NBO) analysis and HF computations confirm the occurrence of strong intra- and intermolecular NH·O and OH·O ionic hydrogen bonding between charged species providing the noncentrosymmetric structure in the LAN crystal. Copyright © 2008 John Wiley & Sons, Ltd.

20 citations


Authors

Showing all 2111 results

NameH-indexPapersCitations
M. Santosh103134449846
Sabu Thomas102155451366
S. Suresh Babu7049817113
K. Krishna Moorthy542639749
Sathianeson Satheesh5317211099
M. Y. Hussaini4920716794
J.R. Banerjee441465620
C. P. Reghunadhan Nair371814825
K. N. Ninan361594156
Anil Bhardwaj352304527
Ivatury S. Raju331216626
Venkata Sai Kiran Chakravadhanula321023011
P.K. Sinha321182918
J.-P. St.-Maurice311133446
Subramaniam Gopalakrishnan281232951
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202313
202230
2021186
2020160
2019149
2018136