Biomass-derived carbon and polypyrrole addition on SiC whiskers for enhancement of electromagnetic wave absorption

To achieve high-performance electromagnetic (EM) wave absorbing performances, biomass-derived carbon (BDC) and conductive polymer polypyrrole (PPy) were incorporated on SiC whiskers (SiCw) by hydrothermal-carbonization-polymerization. Modulation of the mass ratio of SiCw/glucose (SiCw/Glu) can effectively improve the permittivity of SiCw-BDC composites in a large scale, leading to the enhanced EM wave absorption property. Compared with the wave-transparent of pristine SiCw, the SiCw-BDC composite with the SiCw/Glu mass ratio of 0.5 (S-0.5) shows a strong EM wave absorption capacity with a minimum reflection loss (RLmin) value of - 24.6 dB at 13.2 GHz, and its effective bandwidth is up to 6.8 (11.2-18.0) GHz, which could achieve effective absorption of EM waves in entire Ku-band with a wide thickness range of 2.28-2.49 mm. Adjusting the polymerization time of PPy could efficiently control the EM wave absorbing performance of SiCw-BDC/PPy heterostructures, and the sample SiCw-BDC/PPy heterostructure with 1.0 h polymerization time exhibits the optimal microwave absorption property, with a RLmin value of -52.4 dB at 11.4 GHz and effective bandwidth of 8.1 (9.0-17.1) GHz. The electronic dipole polarization, relaxation polarization loss and interfacial polarization with the matched characteristic impedance and improved loss ability within SiCw-BDC/PPy heterostructures are major determining factors of excellent EM wave absorption properties, and the SiCw-BDC/PPy heterostructures in this study are as a promising candidate for next-generation high-performance EM wave absorber for practical applications.