Tensile and Dynamic Mechanical Properties of Natural Rubber and Polyurethane Composites Filled with Cobalt Ferrite

Incorporation of magnetic powders into polymers gives rise to electromagnetic properties useful in sensors and electromagnetic wave absorbers. However, such advantageous properties are introduced in polymer composites at the expense of some mechanical properties. This work aims to explore the effects of magnetic cobalt ferrite (CoFe ₂ O ₄ ) fillers on the tensile and dynamic mechanical properties of natural rubber (NR) and polyurethane (PU) matrices from 0 to 45 phr prepared using a 2-roll mill. The tensile properties deteriorated in the case of NR whereas the storage modulus was reduced for PU composites. The CoFe ₂ O ₄ inhibited the crosslinking and orientations to form crystallites in NR and reduced the stiffness of PU due to poor adsorption between the matrix and fillers. One effect in common was the reduced damping coefficient in both NR and PU composites by the incorporation of CoFe ₂ O ₄ .