ELECTRIC AND MAGNETIC-PROPERTIES OF A THERMOPLASTIC ELASTOMER INCORPORATED WITH FERROMAGNETIC POWDERS

The electric and magnetic properties of a composite material consisting of a thermoplastic elastomer incorporated with iron powder and nickel-iron alloy powder were investigated. The volume fraction of the powder fillers ranged from 0.1 to 0.5. The composites were characterized in terms of their volume and surface resistivities, permittivities and electric loss factors and magnetic permeabilities and magnetic loss factors. With the addition of the ferromagnetic powders, the volume and surface resistivity values of the composites decreased by more than seven orders of magnitude, the permittivity values increased 10 fold and magnetic permeability values increased by a factor of about 6. The ferromagnetic powders were more effective in contributing to the electric and magnetic properties of the composite at higher loading levels. Frequency variation of ac electric and magnetic properties were also measured in the range 20 Hz to 1 MHz. The permittivity values decreased gradually with increasing frequency, whereas the magnetic permeability values remained insensitive to frequency in the measurement range. The electric and magnetic loss factors were negligible, less than 0.1, above 1 kHz, whereas they increased to substantial values of up to 10 at frequencies below 100 Hz.