Synthesis and electromagnetic absorption properties of Fe_3O_4@C nanofibers/bismaleimide nanocomposites

摘要

Carbon nanofibers containing Fe_3O_4 nanoparticles (Fe_3O_4@C nanofibers) were synthesized by electro-spinning technique followed by heat treatment, and then the as-prepared nanofibers were loaded in bismaleimide (BMI) resin to prepare nanocomposites. The phase structure and morphology of nanofibers were characterized by X-ray diffraction and scanning electron microscope, respectively. The complex permittivity and permeability of nanocomposites were measured by vector network analyzer using a coaxial line method in the frequency range of 1-18 GHz, and the microwave absorption performance was accordingly evaluated. The results indicated that the Fe_3O_4@C nanofibers/BMI composites showed excellent low-frequency electromagnetic wave absorption properties with a minimum RL value of —22 dB at 2.1 GHz corresponding to a thickness of 6 mm and exceeding —10 dB with thickness of 3-6 mm in the whole S band (2-4 GHz). The strong absorption in low frequency is attributed to good matching characteristics of dielectric loss and magnetic loss, which can be efficiently tailored by combination of magnetic Fe_3O_4 and dielectric carbon layer through electrospining technology. The novel Fe_3O_4@C nanofibers loaded in BMI resin can provide an effective solution for pressing problem in present that how to produce lightweight microwave absorbing nanocomposites with excellent low-frequency electromagnetic absorption properties.