The diminishing effect of Electromagnetic Interference (EMI) on the performance of electronic and electrical equipment has brought about a need to develop materials with improved EMI shielding capabilities. This study aims to investigate methods of dispersing magnetic nanoparticles in epoxy resin through variations in surface treatment and sample loading, as well as investigating the magnetic properties of such nano-composites relevant to EMI shielding applications.

In order to optimise the EMI shielding effectiveness, dispersion of Fe3O4 ferromagnetic nanoparticles throughout the polymer matrix was enhanced through surface functionalisation. Via a direct silanisation method, organosilane agents of 3-aminopropyltriethoxysilane (APTES) and 3-glycidoxypropyltrimethyoxysilane (GPTMS) were employed to functionalise the nanoparticle surfaces with amine and epoxy functional groups respectively. The presence of such active groups was confirmed through FTIR spectra and zeta potential analysis. When compared to bare magnetite, magnetic property characterisation through VSM showed that the thin silane layer only caused a slight reduction of saturation magnetization. The measurements of magnetic permeability and dielectric permittivity of the various blends indicated that the reflectivity loss was greater in the nano-composites containing silane-treated particles, to better suit EMI shielding applications. Blends containing magnetic nanoparticles prepared by surfactant method, and using polypyrrole, were also investigated, along with carbon and platinum-doped gamma Fe2O3 nanoparticles, custom-made using flame spray pyrolysis.