Dielectric Studies on Magneto-elastomer Composites Filled with Soft Ferrites

Prema. K. H

Abstract

Magneto-elastomer composites are flexible magnetic composites which can be synthesized by incorporating ferrites into elastomers. These composite materials are in par with their ceramic counter parts and are potential substitute for ferrites in various applications. Advantage of these materials is the processability and mouldability into desired shapes. Dielectric property of elastomers is modified with the incorporation of soft ferrites like nickel ferrite. They can be used as microwave absorbing materials. EPDM based magneto-elastomeric composites are prepared with various weight fraction of nickel ferrite. Physical properties such as dielectric and magnetic properties are evaluated. The observed data indicates that frequency dependence of the dielectric constant follows Maxwell-Wagner interfacial polarization. Dielectric and magnetic properties of these composites increase with an increase in volume fraction of the magnetic filler. Some mixture equations are applied to correlate the dielectric permittivity of matrix, filler, and composites. Dielectric constant of nickel ferrite increases with increase in temperature. Temperature dependence of dielectric constant of rubber ferrite composites shows a decrease in these values with increase in temperature. AC conductivity studies of the ceramic filler and composites are also conducted from the measured data. The results arrive at the conclusion that magnetic and dielectric properties of rubber ferrite composites can be tailored by proper loading and a judicious choice of the magnetic filler

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