▎ 摘　　要

Polystyrene (PS) composites with satisfactory electromagnetic interference (EMI) shielding performance were prepared by solution blending of PS with thermally exfoliated and reduced graphene oxide (TGO) and modified Fe3O4 nanoparticles. For comparison, Fe3O4@-reduced graphene oxide (RGO) hybrid and its PS composites were also prepared. The morphologies of Fe3O4@RGO hybrid and Fe3O4 nanoparticles were studied in terms of microstructure and magnetic properties. Surface modification of Fe3O4 nanoparticles enhances their compatibility with PS and thus their uniform dispersion in the PS matrix. Much higher electrical conductivity and EMI shielding effectiveness are achieved for PS/TGO/Fe3O4 composites in comparison to those of PS/Fe3O4@RGO composites. Interestingly, PS/TGO/Fe3O4 composites exhibit obviously improved EMI shielding effectiveness in relative to that of PS/TGO composite although their electrical conductivities are similar. The EMI shielding effectiveness of PS/TGO/Fe3O4 composite is more than 30 dB in the frequency range of 9.8-12 GHz with only 2.24% of graphene. The effect of Fe3O4 size on the composite properties is investigated and the EMI shielding mechanism is discussed. (C) 2014 Elsevier Ltd. All rights reserved.