Electrospun magnetic carbon composite fibers: Synthesis and electromagnetic wave absorption characteristics

摘要

Electrospun polyacrylonitrile (PAN)-based carbon composite fibers embedded with magnetic nanoparticles have been developed as materials for electromagnetic wave absorption. The nanocomposite fibers were prepared by electrospinning from a dispersion of magnetite (Fe_3O_4) nanoparticles stabilized by L-glutamic acid in a solution of PAN and N, N-dimethyl formamide. The Fe_3O_4-embedded PAN nanofibers were stabilized at 270°C in air and carbonized at 800°C in nitrogen. The Fe_ 3O_4 nanoparticles were crystalline with a particle size of about 7 nm, most of which was reduced to Fe_3C with agglomerates of up to 50 nm diameter in the carbon fibers. The carbon morphology was mostly disordered, but exhibited a layered graphitic structure in the vicinity of the nanoparticles. The carbon composite fiber exhibited ferromagnetic behavior, and the induced magnetic saturation per unit mass of fibers increased with increasing Fe_3O_4 content in the precursor. The complex relative dielectric permittivity was tuned by adjusting the amount of Fe _3O_4 in the carbon fiber precursor. With increasing Fe _3O_4 content, good electromagnetic wave absorption characteristics were observed below 6 GHz, even for samples with fiber loadings as low as 5 wt %.