Material Research Cell

Vadodara, India

Material Research Cell

Vadodara, India
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Joshi N.J.,Material Research Cell | Joshi N.J.,Bhabha Atomic Research Center | Rakshit P.B.,Material Research Cell | Grewal G.S.,Material Research Cell | And 2 more authors.
AIP Conference Proceedings | Year: 2013

In this work, attempts are made to prepare ceramic polymer-composite followed by characterization of dielectric properties. The Barium Titanate ceramic powders are synthesized using the hydrothermal process. Silane treatment is carried out on Barium Titanate powder to increase its compatibility with polymer, followed with preparation of ceramic-polymer composite. Polyvinyl Butyral (PVB) is used as matrix for preparation of the composites and the concentration of Barium Titanate is increased from 60 to 90 wt%. Dielectric properties such as volume resistivity, dielectric constant, dissipation factor are evaluated. Results indicate that the dielectric constant and dissipation factor vary between 52 to 120 and 0.01 to 0.07; respectively as the relative ratio of polymer and silane modified Barium Titanate is varied. Specifically, at 90 wt% of silane modified Barium Titanate, the highest dielectric constant of 123 along with dissipation factor of 0.07 is obtained. © 2013 AIP Publishing LLC.

Rakshit P.,Material Research Cell | Joshi N.,Material Research Cell | Joshi N.,University of Sao Paulo | Jain R.,Material Research Cell | Shah S.,M. S. University of Baroda
Polymer - Plastics Technology and Engineering | Year: 2016

In this article, polyurea coatings were synthesized by reaction between toluene diisocyanate, and polyether difunctional and trifunctional amines PO-1 and PO-2 by incorporating urea linkage. The isocyanate-terminated prepolymers formed were further reacted with short-chain amines as chain extender as well as curing agents. These resins were synthesized by varying the molar ratio of amines and isocyanate and keeping the molar ratio of other monomers constant. The presence of functional groups were determined using Fourier transform infrared spectroscopy. The thermal stability of polymers was determined using the thermogravimetric analysis and differential scanning calorimetry. The polymers were further tested for mechanical and electrical properties. It was observed that on increasing the hard segments in the polymer the electrical properties increase whereas elongation decrease. As isocyanate content increases, crosslinking increases resulting in improvement in dielectric properties. The maximum dielectric strength observed was 45 kV mm−1 and dissipation factor was 0.068. © 2016, Copyright © Taylor & Francis Group, LLC.

Rakshit P.B.,Material Research Cell | Jain R.C.,Material Research Cell | Shah S.R.,M. S. University of Baroda | Shrinet V.,Material Research Cell
Polymer - Plastics Technology and Engineering | Year: 2011

Cycloaromatic polyamines based on aniline, 4,40-diaminodiphenylmethane and formaldehyde have been synthesized varying the molar ratio of aniline and formaldehyde keeping the amount of 4,4'-diaminodiphenylmethane constant via a single-step process, coded as PO1, PO2 and PO3. The resinous material of polyamines has been employed for curing studies of commercially available epoxy resinsw. The effect of time, temperature and the concentration of polyamines as curing agent have been studied. The epoxy specimens were further used for testing different dielectric properties such as resistivity, dielectric strength, dissipation factor and dielectric constant with an objective of their application as dielectric materials. © ERDA-Vadodara.

Joshi N.J.,Material Research Cell | Grewal G.S.,Material Research Cell | Shrinet V.,Material Research Cell | Govindan T.P.,Material Research Cell | Pratap A.,M. S. University of Baroda
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2012

In this study, an effort has been made to synthesize nano-scale barium titanate powder by sol-gel and hydrothermal methods. Characterization of the synthesized Barium Titanate is conducted by using X-ray diffraction for crystallite size, Transmission Electron Microscopy for particle size and scanning electron microscopy for surface morphology. It is observed that the powders prepared by Sol-gel and hydrothermal routes have almost similar average crystallite size of 34 ± 2 nm. Electrical properties such as dielectric constant, dielectric dissipation factor and electrical resistivity have also been measured. Hydrothermal process has enabled the synthesis of material with higher dielectric constant of 4000 compared to the Sol-gel route value of 1600. The dielectric dissipation factor is measured and found to be below 0.3 over a wide range of frequencies for powders generated using both processes. © 2012 IEEE.

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