Polypropylene (PP) was investigated as a polymeric matrix of functional composites by melt mixing in a compression mould. The sample with 15 wt.% loading of cobalt ferrite (CoFe₂O₄) increases the electrical permittivity as a result of Maxwell-Wagner effect and induces ferrimagnetic properties in PP composites. By increasing the CoFe₂O₄ loading to 55 wt.%, the magnetization and relative permittivity were substantially raised. Interestingly, this high loading which was comparable to the percolation threshold, did not affect the coercivity. Both low and high CoFe₂O₄ loadings have insignificant effects on magnetic permeability spectra. The results suggest that the melt mixing is a facile route to incorporate high loading of magnetic powder into plastics, leading to composites of enhanced electromagnetic properties.
