Preparation And Application Of Lignin-based Carbon/Iron Oxide Composite Nanofibers As Microwave Absorption Material

The technology of electrospinning introduce a new way to improve the using value of plantfiber resource. Lignin-based nanofibers and carbon nanofibers prepared by electrospinning isbecoming a research hotspot.Fe3O4nanoparticle is a kind of typical magnetic material due to its low price andexcellent magnetic properties of super paramagnetic, high magnetic saturation and magneticloss because of nano effect, and carbon nanofibers have the advantage of less density and highdielectric loss. Both of the two material are applied to microwave absorption.Carbon/Fe composite nanofibers (CNF) were prepared by electrospinning acetic acidlignin (AAL) separated from bamboo, polyethylene oxide (PEO) and iron (Ⅲ) acetylacetonate(AAI) compound solutions, followed by stabilization and carbonization processes. Themicromorphology, thermal properties, formation of carbon structure and crystal of iron oxidewere characterized by fourier transformed infrared (FT-IR), scanning electron microscopy(SEM), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), Ramanspectroscopy and X-ray diffraction (XRD), and the effect of AAI content and temperature ofcarbonization on micromorphology and carbon structure were studied. The electromagneticparameters of lignin-based CNF was studied in the frequency range of1-18GHz by vectornetwork analyzer (VNA), and the absorption ability was evaluated by RL calculated accordingto electromagnetic parameters. The results showed that:1.The excellent property of forming fibers was showed by electrospinning the AAL/PEO/AAIcompound solution system when the ratio of AAL and PEO is19:1. The minimum averagediameter of electrospun nanofibers was about300nm.2.The continuous and uniform stabilized nanofibers could be prepared successfully bythermostabilizing with AAI content over5wt%. The electrospun nanofibers fused in thethermostabilization stage without AAI. The morphology of fibers was ruined by high heatingrate.3.The continuous lignin-based CNF was prepared successfully after carbonization at differenttemperature. The minimum average diameter of CNF was about200nm. Iron oxidenanoparticles were observed on the surface of CNF. Iron oxide exhibited catalytic effect on carbonization that promote graphitization below a certain AAI content and inhibit the formationof graphitized layers.4.The sample of CNF carbonized at700℃with AAI content10wt%exhibited the optimalimpedance matching. The maximum absorption occurred at16GHz2mm thick, and thestrongest RL was-57dB with a broad effective bandwidth of6GHz.