Microwave Absorption Performance of Single-Layer and Multi-Layer Structures Prepared by CNTs/Fe3O4 Nonwoven Materials

Abstract

Electromagnetic radiation can cause serious harm to the human body, such as the rise in body temperature and the decrease in immune function. In this study, the carbon nanotubes (CNTs)/Fe3O4 nonwovens were used to prepare wearable flexible absorbing materials. First, the single-layer absorbing structures were prepared by hot rolling, dipping, and film fabrication, respectively. Then, the single-layer structures were combined to form the multi-layer absorbing structures. By testing and analyzing the absorbing performance of various structures in the X-band frequency range, the optimum combination scheme was found, together with a good reflection loss value of CNTs/Fe3O4 nonwoven material. The experiment results displayed that the single-layer hot-rolled nonwovens modified by CNTs have the best wave absorbing performance. Its minimum reflection loss of −18.59 dB occurred at 10.55 GHz, and the efficient frequency occurred at 8.86–12.40 GHz. The modified film can significantly improve the absorbing performance of multi-layer structures. In addition, the absorbing performance was closely related to both the place where the absorbing film was introduced and the type of absorbing fillers. When the film-forming CNTs (FC) film was located at the bottom layer of the multi-layer structure, the hot rolled CNTs hot rolled mixed reagent film forming CNTs (HC-HM-FC) structure constructed exhibited the best absorbing effects. Its minimum reflection loss can reach −33 dB, and the effective absorbing frequency range covered half of the X-band.

Structure Design, Surface Modification, and Application of CNT Microwave‐Absorbing Composites

“…Zhan et al. [ 193 ] modified the non‐woven fabric by using needled nonwovens as matrix, CNT and Fe 3 O 4 as absorbent, and prepared a variety of single‐layer absorbing structures through hot rolling, impregnation, and film formation. Needled nonwovens have a natural irregular porous structure due to the entanglement of short fibers, which contributes to the construction of efficient microwave‐absorbing structures.…”

Performance Simulation and Fused Filament Fabrication Modeling of the Wave-Absorbing Structure of Conductive Multi-Walled Carbon Nanotube/Polyamide 12 Composite

“…A large number of studies have shown that multi-walled carbon nanotubes (MWCNTs), as excellent fillers that can improve the mechanical strength, electrical properties, and wave absorbing properties of composites, are widely used as wave absorbers. At the same time, their cost is relatively low, and they have great practical application value [ 9 , 10 , 11 , 12 ]. However, their compatibility with the polymeric matrix as a wave absorber is a very acute problem.…”

CoFe2O4 Nanoparticles Grown within Porous Al2O3 and Immobilized on Graphene Nanosheets: A Hierarchical Nanocomposite for Broadband Microwave Absorption

“… 4 − 6 The high-frequency microwave (MW) induces some undesirable EM noise, which not only interrupts the electronically controlled systems but also harms human health by elevating the temperature in living tissues and weakening the immune system of the body. 7 Moreover, overexposure to MW may also enhance the risk of cancer, tachycardia, induces damage to DNA strands in the rat brain cells, etc. 4 , 8 These reasons are triggering the demand to develop MW-absorbing materials.…”

“…The exponential augmentation of information technology (IT) and extensive use of electronic and electrical devices, wireless communications, local area networks, radar systems, etc. cause electromagnetic interference (EMI). − In addition, the EM radiations generated by these devices create EM pollution globally and pose some adverse effects on human health as well as on other biological systems. − The high-frequency microwave (MW) induces some undesirable EM noise, which not only interrupts the electronically controlled systems but also harms human health by elevating the temperature in living tissues and weakening the immune system of the body . Moreover, overexposure to MW may also enhance the risk of cancer, tachycardia, induces damage to DNA strands in the rat brain cells, etc. , These reasons are triggering the demand to develop MW-absorbing materials.…”