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Microwave Dielectric Properties of Elastomers Containing Particulate Metal Fillers

Published online by Cambridge University Press:  28 February 2011

Barry G.M. Helme
Barry G.M. Helme*
Affiliation:
Department of Materials Engineering and Materials Design, University of Nottingham, University Park, Nottingham, NG7 2RD, England, UK. Royal Society/SERC Research Fellow on secondment from Quasar Microwave Technology Ltd., Moorswater, Liskeard, Cornwall, PL14 4LQ, England, UK
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Abstract

Elastomers have been manufactured containing varying concentrations of particles of Ag/Al, Ag/Cu, Ag/Ni, Ag/glass (G3), Ni/graphite, Ni, and Ag. Their dielectric and microwave properties have been measured between 0.4 GHz and 40 GHz and at temperatures between ambient and 100°C. The filler particles are small relative to the microwave wavelength but larger than the skin depth. Sheets of these elastomers of up to 2 mm thickness gave been subjected to cyclical stretching of up to 40% elongation and up to 10° cycles. The microwave properties have been measured as a function of numbers of stretching cycles and composition of elastomer. Some correlations were found between the composition, the microwave properties and the number of stretch cycles completed.

It was found in general that repeated stretching degraded the initially high conductivity of the loaded elastomers. This effect was also revealed by the increase in microwave transmissivity through the sheets, and a decrease in reflectivity. Formulations of elastomer-metal particle mix have recently been produced which have a microwave transmissivity more Phan 80 dB below the incident signal, for a 2 mm thick sample, even after 106 stretching cycles of 20% elongation. This property is of great value for the use of the elastomer as a reflective microwave shield.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 189: Symposium L – Microwave Processing of Materials II , 1990 , 517
Copyright
Copyright © Materials Research Society 1991

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