Magnetic Properties of Iron Nanoparticles Distributed in Polymer Matrix: Theoretical and Experimental Approach

A PP+Fe nanocomposite's phase identification, morphology, nanoscale imaging and magnetic structure have been determined with the use of the X-ray diffraction, scanning electron microscopy, atomic force microscopy and magnetic force microscopy techniques, respectively.In a polymer matrix, iron nanoparticles are found to be randomly distributed and their distribution was described by the log-normal function.The theoretically determined dependence of the particles' size on concentration showed good agreement with the scanning electron microscopy results.The present study showed that the magnetic and geometric sizes of Fe nanoparticles in the polymer matrix differ from each other.Additionally, the magnetic size of the Fe nanoparticles of the identical geometric size decreases with increasing filler concentration in the polymer matrix.The increase of Fe nanoparticles' concentration presumably leads to oxidation of the surface layer which is likely non-magnetic.The magnetic behaviour of the PP+Fe nanocomposite depending on iron content was investigated both theoretically and experimentally.The results of the magnetic measurement indicated the presence of a natural oxide layer in addition to pure iron.The comparison of the theoretical curve of M (H) with that of the magnetic measurement clearly showed that the obtained curves share the same qualitative feature.In both cases, for all concentrations of the nanoparticles, an open hysteresis loop characteristic for multi-domain particles was observed.The qualitative difference between the experiment and theoretical calculations was explained by the influence of several factors including the microstructure of the medium and the magnetic domain structure of the iron nanoparticles in the polymer matrix.