Electromagnetic and Dynamic Mechanical Properties of Extruded Cobalt Ferrite-Polypropylene Composites

Cobalt ferrites of 0-45wt% were incorporated in polypropylene by the extrusion technique. With increasing magnetic loading, the magnetizations were linearly increased according to the rule of mixture and the electrical permittivity was also proportional to the loading as described by Wagner's equation. The magnetic permeability may be increased but was reduced to minimal at high frequencies because of the substantial coercive field of cobalt ferrites after the extrusion. Without considerable adsorption of polymer matrix on magnetic fillers, the storage and loss modulus from 30 to 180 degrees C of polypropylene were decreased by cobalt ferrites additions.