Electromagnetic interference shielding MWCNT-Fe3O4@Ag/epoxy nanocomposites with satisfactory thermal conductivity and high thermal stability

Hierarchical composite nanoparticles of multiwall carbon nanotube (MWCNT)-Fe3O4@Ag combining electrical conductivity and magnetism were obtained from acyl-amine reaction between carboxylation of Fe3O4@Ag (Fe3O4@Ag-COOH) nanoparticles and amino functionalized MWCNTs (MWCNTs-NH2). Finally, the MWCNT-Fe3O4@Ag/epoxy nanocomposites were fabricated via blending-casting method. When the mass ratio of MWCNTs-NH2 to Fe3O4@Ag-COOH was 9:1 (MF-10), the corresponding epoxy nanocomposites presented an optimal electrical conductivity and electromagnetic interference (EMI) shielding effectiveness (SE). Furthermore, the MF-10/epoxy nanocomposites with 15 wt% MF-10 presented a satisfying EMI SE of 35 dB and high electrical conductivity of 0.280 S/cm, satisfactory thermal conductivity (thermally conductive coefficient, λ of 0.46 W/mK), outstanding Young's modulus of 4.60 GPa & hardness value of 0.26 GPa and excellent thermal stability (THRI of 183.4 °C). The introduction of Fe3O4@Ag nanoparticles not only enhanced the interaction among MF-10, so as to promote the formation of conductive networks, leading to higher λ and EMI SE value, but also contributed to hysteresis loss of electromagnetic waves, and offered more interfaces to reflect and reabsorb electromagnetic waves, resulting in highly improved attenuation of electromagnetic waves.