Fine particles of nickel ferrite are synthesized by the sol-gel technique and characterized by the X-ray diffraction method. These materials are incorporated in ethylene propylene diene rubber (EPDM) according to a specific recipe for various loadings. The rubber ferrite composites (RFCs) thus obtained have several applications, such as microwave absorbers, EMI shielding materials, etc. In the present study, microwave attenuation and dielectric properties of RFCs are studied in the X- and S-band frequencies. Real and imaginary parts of the dielectric permittivity are determined by cavity perturbation method. Dielectric permittivity in X-band frequency, based on Maxwell—Garnet equation is calculated and presented here.
Nanoparticles of nickel ferrite are synthesised by sol-gel technique. They are then characterised by X-ray diffraction technique (XRD) and Vibrating sample magnetometer (VSM). Precharacterised ultra fi ne nickel ferrite is then incorporated in ethylene propylene diene rubber (EPDM) according to a specifi c recipe. The prepared rubber ferrite composites (RFCs) are found to have appreciable mechanical and dielectric properties. Addition of appropriate amount of carbon black to RFCs substantially improves its dielectric properties. Variation of dielectric properties of RFCs with frequency is studied in the frequency range 0.1-8 MHz and is found to vary in accordance with Maxwell-Wagner interfacial polarisation. dc conductivity of the RFCs is also measured and correlated with fi ller loading.
Rubber ferrite composites were prepared by incorporating nickel ferrite in a neoprene rubber matrix. Kinetics of the cure reaction were determined from the rheometric torque values and found to follow first-order kinetics. Analysis of the swelling behavior of the rubber ferrite composites in toluene elucidates the mechanism of solvent penetration and sorption characteristics, and reveals the extent of the physical interaction of the ferrite particles with the neoprene rubber matrix. Mechanical properties of rubber ferrite composites were determined, which support the reinforcing nature of nickel ferrite to the neoprene rubber matrix. These results show that magnetic composites with the required processing safety can be prepared economically by incorporating higher amounts of nickel ferrite in the neoprene rubber matrix.
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