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Chopra S.,Defence Materials Stores Research and Development Establishment | Alam S.,Defence Materials Stores Research and Development Establishment
Journal of Applied Polymer Science | Year: 2013

Novel flexible polyurethane (PU) composite films containing nano-barium hexaferrite (BaF) and nano-barium titanate (BT) have been synthesized and characterized. The PU nanocomposites were synthesized from fullerenol and prepolymer of hexamethylene diisocyante and polytetramethylene glycol by adding 1-3% each of BaF (high permeability) and BT (high permittivity). The incorporation of the nanopowders was confirmed by X-ray diffraction (XRD), transmission electron microscopy, and energy dispersive X-ray diffraction (EDX). Study of thermal properties by thermogravimetric analysis and dynamic mechanical analysis revealed enhanced thermal stability of the nanocomposites. Study of mechanical properties showed that the tensile strength had increased remarkably in the nanocomposites. The electromagnetic-absorbing properties were studied by measuring the complex permeability and permittivity in the frequency range of 8.2 to 12.4 GHz. The good reflection loss of the nanocomposites at such low filler content suggests its potential applicability as a radar absorber. © 2012 Wiley Periodicals, Inc. Source


Chopra S.,Defence Materials Stores Research and Development Establishment | Pandey M.K.,Defence Materials Stores Research and Development Establishment | Alam S.,Defence Materials Stores Research and Development Establishment
Journal of Applied Polymer Science | Year: 2011

Novel nanocomposites of barium hexaferrite- and fullerene-containing polyurethane were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and energy-dispersive X-ray diffraction. The nanoparticles showed good dispersion in the polyurethane matrix. Their thermal, mechanical, and electromagnetic absorbance properties were studied. The complex permeability and permittivity were measured in the frequency range of 8.2-12.4 GHz. The maximum reflection loss of the nanocomposites was found to increase with increasing the ferrite content from 1% to 5%, with maximum value of -7.5 dB at only 5% composition. The incorporation of nanofiller not only imparts mechanical strength to the nanocomposite but also shows good radar-absorbing properties at only 5% filler concentration. © 2011 Wiley Periodicals, Inc. Source

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