Ya-Nan Gao,Ye Wang,Tian-Ning Yue,Biao Zhao,Renchao Che,Ming Wang
Absorption-dominant electromagnetic shielding materials can effectively reduce secondary pollution in the shielding process, and have greater significance in practical applications. Herein, silver (Ag) micro-tubes with superstructure, which were fabricated via using poly(lactic acid) (PLA) fibers as templates, were used to achieve the composites with ultrahigh, lightweight, and absorption-dominant electromagnetic shielding performance. The Ag nanoparticles were firstly deposited on the surface of PLA fibers by chemical reduction. The Ag micro-tubes were obtained by etching the PLA fibers in the core. The Ag nanoparticles were stuck together to form the Ag micro-tubes by polymer chains. The ultrahigh electromagnetic interference (EMI) shielding effectiveness (SE) of ∼110 dB was found in the Ag micro-tubes composed with polydimethylsiloxane or PLA with 1.5 mm in thickness. Due to the micro-tube structure, the composites containing with Ag micro-tubes exhibited absorption dominant shielding mechanism and low density. The absorption coefficient (A) value could reach 0.79 in the composites with Ag micro-tubes. The ultrahigh EMI SE performance and absorption dominant shielding mechanism of the composites was ascribed to the superstructure of the Ag micro-tubes which could efficiently create surface plasmon resonance, electronic vibration, interfacial polarization, capacitance effect and conductive loss. The work provides a new idea for preparing ultrahigh electromagnetic shielding materials with high absorption and low density.
High conductivity can give materials excellent electromagnetic shielding performance, but it leads to serious impedance mismatching and causes inevitable secondary pollution. Developing materials with both excellent microwave absorption and microwave shielding performance remains a formidable challenge. Herein, absorption-type electromagnetic shielding materials with high electromagnetic shielding effectiveness (EMW SE) values were successfully prepared by combining hollow silver micro-tubes and magnetic nano-barium ferrites. The electromagnetic parameters and impedance matching of the composites could be easily regulated by changing the ratio of silver micro-tubes (C) and nano-barium ferrites (M). Thanks to micro-tube structure and the electric-magnetic synergism of the fillers, the composites with the C:M ratio of 9:1 exhibited a high absorption coefficient ( A ) value of ∼0.77 and a high EMW SE value of ∼100 dB, simultaneously. The absorption-type shielding mechanism of the composites was also evaluated via discussing real and imaginary parts of complex permittivity , real and imaginary parts of complex permeability, and Cole-Cole curves. Furthermore, the composites with the C:M ratio of 3:7 exhibited excellent microwave adsorption performance with the minimum reflection loss of −46.3 dB at thickness of 3.0 mm and a maximum effective absorption band-width of 6.13 GHz.
危险品化学品经营许可证（带存储）