Fabrication and microwave absorbing properties of CCB@Fe₃O₄/ NR absorbing films

Exploring electromagnetic wave (EMW) absorbing materials with excellent performance is the main method to solve electromagnetic pollution. However, it remains a challenge to meet the high performance and practical application requirements of materials simultaneously. Conductive carbon black (CCB)@nano ferroferric oxide (Fe₃O₄)/natural rubber (NR) absorbing films with excellent mechanical and EMW absorption properties were prepared by sol-gel method, plasticizing, blending and vulcanization, and the mechanical and EMW absorbing properties of the films were controlled by adjusting the addition amount of CCB@Fe₃O₄. The introduction of the CCB@Fe₃O₄ composites greatly ameliorates the interfacial loss and polarization loss of the films, in which the CCB can enhance the mechanical properties while improving the dielectric constant and conductivity of the materials. The film achieves the minimum reflection loss (RL) of -40.5 dB and maximum effective absorption bandwidth (EAB) of 2.4 GHz with the thickness of 5.0 mm when the CCB@Fe₃O₄ was added at 29wt%, and exhibited the optimal tensile strength, hardness and wear properties. The remarkable EMW absorbing properties of the material originate from impedance matching, strong EMW attenuation and high conduction loss caused by the synergistic effect of dielectric-magnetic loss. This work provides a new mentality for the structure design and practical application of natural rubber-based absorbing films.