Electromagnetic Interference Shielding Materials Research Articles

Gradient structure silicone rubber composites for selective electromagnetic interference shielding enhancement and low reflection

Electromagnetic interference (EMI) shielding composites with gradient filler distributions were fabricated with the application of an induced magnetic field. The selective enrichment of nickel-coated carbon fibers within a core-shell structure effectively strengthens the overlap between fillers. This composite exhibited outstanding conductivities (98.2 S/m) that were two orders of magnitude greater than composites that possessed uniformly dispersed fillers because of the favorable inductive effect and the perfect loading of Ni nanoparticles. In addition, the sandwich structure causes the electromagnetic (EM) waves to reflect multiple times, further improving the EMI shielding effectiveness (SE) of the composite and resulting in a maximum SE of 60.8 dB. The introduction of magnetic Fe3O4@MWCNTs greatly increased the EM wave absorption efficiency from 14% to 45%, which resulted in low reflection peaks due to the resonant cancellation of the incident and reflected EM waves. The reflectivity of the composite was only 4% at 8.2 GHz, indicating a high absorption rate of 96% at this frequency. Furthermore, the composite shows excellent EMI shielding stability after 1000 repeated bends. This work thus describes a new approach to the preparation of high-performance (high-efficiency and low-reflectivity) EMI shielding materials and broadens their applicability to precision electronic devices and flexible wearable devices.

Methylene blue adsorption derived thermal insulating N, S-co-doped TiC/carbon hybrid aerogel for high-efficient absorption-dominant electromagnetic interference shielding

The development of absorption-dominant electromagnetic interference (EMI) shielding materials with high-efficiency EMI shielding effectiveness (SE) and low reflection (R) is crucial but challenging for next-generation electronics devices and telecommunication. In this regard, a facile and environmentally friendly approach was proposed to fabricate N, S-co-doped TiC/carbon hybrid aerogels with hierarchically porous architecture through MXene/cellulose hybrid hydrogels as precursors for adsorbing dyes, followed by freeze drying and carbonization process. Profiting from the synergistic effect of highly interconnected three-dimensional (3D) porous structure, heterogeneous conductive network with greatly conductive difference as well as heteroatoms-doping induced dipole polarization, the resultant aerogel with an ultra-low density (47.1 mg/cm3) achieves a highly efficient EMI SE of 84.3 dB at 12.4 GHz (average 81.8 dB in the X-band) and a superior absorption coefficient of 0.68 simultaneously. Meanwhile, the highly porous structure endows the prepared aerogels with outstanding thermal insulating capacity, which is essential to provide infrared stealth and radar stealth for military equipment and to protect sensitive electronic devices from high-temperature attacks. This work offers a prospective strategy for constructing high-performance absorption-dominated EMI shielding materials with excellent thermal insulation properties, and the obtained aerogels present broad application prospects in the fields of aviation, portable electronic equipment and national defense industry.

Multifunctional graphene/carbon fiber aerogels toward compatible electromagnetic wave absorption and shielding in gigahertz and terahertz bands with optimized radar cross section

Lightweight absorption-dominated electromagnetic interference (EMI) shielding materials with multifunctional integration of multiband absorption, mechanical durability and thermal insulation are urgently required in the practical application of next-generation communication technology combined with flexible electronics. In this work, ultralight and mechanically durable graphene/carbon fiber composite aerogels (CGAs) are synthesized via solvothermal reaction and freeze-drying. The as-prepared CGAs demonstrate excellent compatible electromagnetic wave absorption and shielding performance in both gigahertz (GHz) and terahertz (THz) bands without addition of magnetic component. Specifically, a broad efficient absorption bandwidth of 8.72 GHz at 2–18 GHz and a high mean absorptivity of 97.4% at 0.3–1.5 THz are achieved, respectively. Furthermore, absorbing coatings with CGAs have been proved to contribute to remarkable radar cross section reduction of 39.06 dBm2 by computer-assisted simulation. Additionally, the compressible CGA demonstrates superior and stable EMI shielding performance under in-situ compression. The EMI shielding effectiveness exceeds 35 dB in X-band when a compression ratio of 78.9% is applied. Moreover, CGAs are thermally insulating and self-extinct, making them reliable in practical application. This work provides a series of promising multifunctional lightweight EMI shielding materials for future high-frequency wireless communication.

Reduced graphene oxide(rGO)-Ferrite composite inks and their printed meta-structures as an adaptable EMI shielding material

ABSTRACT Electromagnetic interference (EMI) shielding inks are generally conducting inks and therefore, are mostly reflection based. EMI shielding based on reflection are sometimes not suitable for certain applications apart from the fact that they themselves act as secondary source of EM waves. Here, we develop reduced graphene oxide (rGO)- zinc nickel ferrite (ZNF) and rGO-manganese (Mn)-doped zinc nickel ferrite inks for EM absorption in X-band, which have been tested in liquid state, coatings, and as printed meta-structures demonstrating versatile use of the inks. As a coating, the average EMI shielding of more than 30 dB is achieved in the 8 to 12 GHz range. The absorption properties of the rGO based ink can be increased from 50% to more than 80% by addition of a ferrite composite and can further be tuned by Mn doping. The dielectric measurement studies reveal that addition of Mn creates sites for interfacial polarization. The interfaces between polymer matrix, rGO, ZNF, and Mn contribute to conductivity, dipole and interfacial polarization losses, thereby augmenting absorption dominated EMI shielding. Cole-cole plot for the inks also indicates multiple relaxation processes confirming the role interfaces in absorption properties of the composite ink.

Facile synthesis of ultra-lightweight Ni/NiO/NixPy foams with hollow sandwich micro-tubes for absorption-dominated electromagnetic interference shielding

Absorption-dominated electromagnetic interference (EMI) shielding materials could effectively minimize secondary pollution in the shielding process, which is of great significance in practical applications. Herein, we propose a facile one-step thermal treatment strategy to prepare lightweight Ni/NiO/NixPy foams with a hollow sandwich micro-structure and an absorption-dominated excellent EMI shielding effectiveness (SE). Due to the transformation of the Ni-P alloy coating created by chemical deposition during the heat treatment, the conductivity of Ni/NiO/NixPy micro-tubes decreases from 5.85 × 103 S/m to 3.32 × 10−4 S/m, while its magnetization varies from 0.67 emu/g to 9.39 emu/g with fluctuation. The EMI SE of the foams reaches 41.34 dB at a mere density of 70 mg/cm3 and the normalized specific SE is up to 2261.0 dB cm2/g with an ultra-low density of 35 mg/cm3. The synergy of hollow micro-tubes and multi-interface results in high absorption coefficients (above 0.5) of the Ni/NiO/NixPy foams. This work provides a new idea for the preparation of EMI shielding materials with high absorption, low density, and tunable electromagnetic properties.

Ultrastrong and Hydrophobic Sandwich-Structured MXene-Based Composite Films for High-Efficiency Electromagnetic Interference Shielding.

Electromagnetic interference (EMI) shielding materials are highly necessary to solve the problem of electromagnetic radiation. Transition-metal carbide/nitride (MXene) materials offer great potential for the construction of high-performance EMI shields because of their high electrical conductivity and versatile surface chemistry. However, MXene generally suffers from poor mechanical and oxidation-resistant properties, which hinders its practical applications. Herein, flexible, strong, and hydrophobic sandwich-structured composite films (H-S-MXene), consisting of a conductive MXene layer and supporting aramid nanofiber layer, were fabricated using step-by-step vacuum-assisted filtration and dip coating. Given the unique sandwich structure, hydrogen bonding interactions, and covalent cross-linking of the MXene sheets, the H-S-MXene composite films demonstrated simultaneously excellent EMI shielding and mechanical properties. The EMI shielding effectiveness of the H-S-MXene composite film with 20 wt % MXene content reached 46.1 dB at thickness of 23.2 ± 0.5 μm, and the tensile strength of the film reached 302.1 MPa, which outperformed other reported EMI shielding materials. The excellent mechanical flexibility and hydrophobicity of the H-S-MXene composite films ensured a stable EMI shielding performance, which could withstand cycled bending, torsion, and exposure to aqueous environments. These impressive features made the H-S-MXene composite films promising candidates for electronic devices and aerospace. This study provides important guidance for the rational design of stable MXene-based composites with advanced properties.

Recent Advances in Polymer Nanocomposites for Electromagnetic Interference Shielding: A Review.

The mushrooming utilization of electronic devices in the current era produces electromagnetic interference (EMI) capable of disabling commercial and military electronic appliances on a level like never before. Due to this, the development of advanced materials for effectively shielding electromagnetic radiation has now become a pressing priority for the scientific world. This paper reviews the current research status of polymer nanocomposite-based EMI shielding materials, with a special focus on those with hybrid fillers and MXenes. A discussion on the theory of EMI shielding followed by a brief account of the most popular synthesis methods of EMI shielding polymer nanocomposites is included in this review. Emphasis is given to unravelling the connection between microstructures of the composites, their physical properties, filler type, and EMI shielding efficiency (EMI SE). Along with EMI shielding efficiency and conductivity, mechanical properties reported for EMI shielding polymer nanocomposites are also reviewed. An elaborate discussion on the gap areas in various fields where EMI shielding materials have potential applications is reported, and future directions of research are proposed to overcome the existing technological obstacles.

Flexible, conductive and multifunctional cotton fabric with surface wrinkled MXene/CNTs microstructure for electromagnetic interference shielding

Although ultrathin and flexible conductive textiles are promising for smart wearable electronic devices, the seamless integration of electromagnetic interference (EMI) shielding textiles, strain sensors and Joule heater is still a huge challenge. Herein, a conductive cotton fabric with cross-linked wrinkled microstructure is fabricated via a facile spray-coating approach, formed by carbon nanotubes (CNTs) as skeletons and Ti3C2Tx MXene nanosheets as stacking layers. Benefiting from the unique wrinkled microstructure, the resultant fabric exhibits high EMI shielding effectiveness (EMI SE) of 46.05 dB in the X-band at a thickness of only 138 µm. Furthermore, the specific EMI SE (SSE/t) of the resultant fabric is up to 6.71 × 103 dB cm2 g−1, significantly exceeding most of the currently reported polymeric EMI shielding materials. Due to the high electrical conductivity, the resultant fabric also displays excellent Joule heating performance (46.6 ℃ for PMC3C at the driven voltage of 2 V) and sensitive strain responses. More importantly, the resultant fabric demonstrates outstanding stability and anti-fouling property, offering a huge potential for long-term applications in harsh environments. This work provides a facile strategy to develop multifunctional EMI shielding fabric for human motion detection and personal thermal management.

Lightweight and textured Ni@Cu-encapsulated carbon tube with outstanding electromagnetic interference shielding performance

The low-reflection electromagnetic interference (EMI) shielding material is highly desirable, which would facilitate the reduction of the EM-wave secondary pollution, but classic conflict between performance and density makes it very challenging in practical application. Herein, a textured Ni@Cu-encapsulated carbon tube was designed and fabricated as a conducting material inserted into the middle of polydimethylsiloxane (PDMS) polymer and its application in flexible, light-weight and low-reflection EMI shielding material. Results showed that the active groups on the plant fiber surface could absorb Pd2+, acting as catalytic center, which can catalyze electroless nickel plating (EP Ni) on its surface by means of textured Ni-encapsulated plant fiber. The inside plant fiber was carbonized and attached to Ni-tube inside surface after annealing, owning to the outstanding heat-conducting capability of Ni coating. To be precise, textured Ni encapsulated C tube was fabricated successfully after annealing at 300 °C. Interestingly, the surface Ni tube could catalyze the EP Cu on its surface by means of textured Ni@Cu-encapsulated carbon tube structure, endowing the composites with efficient dielectric loss and magnetic loss capacity. Combined with PDMS coating, a flexible, light-weight and low-reflection EMI shielding material is fabricated successfully. More importantly, it displays outstanding EMI shielding effectiveness of 35.4 dB, lower reflection one of 0.9 dB, higher specific one of 28.7 dB cm3/g, superior flexibility and mechanical properties with a thickness of only 2 mm. This work open a new window for fabricating EMI shielding materials with outstanding EMI shielding performance.

Carbon black incorporated carbon nanofiber based polydimethylsiloxane composite for electromagnetic interference shielding

High-performance electromagnetic interference (EMI) shielding materials that are very elastic and flexible, hydrophobic, and of low density are desperately needed to address the rising electromagnetic pollution problem. This study describes the preparation and characterization of an elastic EMI shielding material which is hydrophobic and of low density. Carbon nanofibers (CNFs) incorporated with carbon black super P ([email protected]NFs) based polydimethylsiloxane (PDMS) composites were fabricated using a combination of electrospinning followed by heat treatment and manual lay-up process. The high electrical conductivity of 2.5 S cm−1 imparted excellent EMI shielding property to [email protected] With a thickness of 0.06 mm and a density of 0.63 g cm−3, [email protected] exhibited high EMI shielding effectiveness (EMI SE) over a wide frequency range (8.2-26.5 GHz). The highest and average values of EMI SE in the range were 55.8 and 50.7 dB respectively. Composites of [email protected] with PDMS also showed similar behaviour. The [email protected] with 9 wt% and 16.6 wt% loading of CBSP exhibited 24,837 and 14741 dB cm2 g−1 of absolute EMI SE (SSEt), respectively, which is remarkably higher than the most reported EMI shielding materials. These results suggest that [email protected] based PDMS composites would be promising for applications as thin, flexible, stretchable, and light EMI shielding materials.

Promising PVDF-CNT-Graphene-NiCo chains composite films with excellent electromagnetic interference shielding performance

Polymer-based composite electromagnetic interference (EMI) shielding materials have aroused great interest among scientific researchers because of excellent properties. Herein, the poly(vinylidene fluoride) (PVDF)-carbon nanotube (CNT)-Graphene (G)-NiCo chains composite film with ultrahigh EMI shielding properties was prepared through solution mixing and compression molding. In the composite film, 1D carbon nanotube (CNT) and NiCo chains connected the surrounding 2D graphene nanoplates and formed interfacial interconnected networks. The electrical conductivity and total electromagnetic interference shielding effectiveness (EMI SE T ) of the samples increased progressively with the increased NiCo quality contents. The resultant PVDF-CNT-G-8NiCo composite film exhibited an excellent electrical conductivity of 9.12 S/cm and an ultrahigh EMI SE T of 63.3 dB. The results were superior to those of PVDF-CNT-8NiCo composite film, clearly confirming the synergistic effect of graphene nanoplates and CNT. The formation of multi-layers interfacial conductive CNT-G-NiCo networks promoted conductive dissipation, multiple reflections and scattering of incident electromagnetic (EM) waves. Meanwhile, this work provides guidance for the rational design of high-performance polymer-based composite EMI shielding materials and has great potential in practical applications. • PVDF-CNT-Graphene-NiCo chains composite film was prepared. • The synergistic effect of CNT, graphene and NiCo alloy formed interconnected networks. • The multi-layers networks promoted conductive dissipation, and multiple scattering of EM waves. • A superior EMI SE T of 63.3 dB were achieved in PVDF-CNT-G-8NiCo composite film.

Lightweight and tough multilayered composite based on poly(aryl ether nitrile)/carbon fiber cloth for electromagnetic interference shielding

Electromagnetic interference (EMI) shielding materials are of vital importance in solving increasingly serious electromagnetic pollution. Currently, metal-based EMI shielding materials (ESMs) are ubiquitously used, however, their drawbacks of high density, low corrosion resistance, and poor flexibility restrict their application scenarios. By contrast, polymer-based composite materials have superior properties such as light weight, great shock absorption performance, and high corrosion resistance, which makes them promising electromagnetic interference shielding materials. In this work, an asymmetric network of the impedance matching layer and conductive shielding layer is constructed by coupling carbon fiber cloth (CFC) with magnetic porous poly(aryl ether nitrile) (PEN) polymer composite. Scanning electron microscopy confirms the alternating layered structure of the composites and the porous structure of the polymer layer. The unique designed composites achieve the highest EMI total shielding effectiveness (SET) of 37.76 dB and absorption shielding effectiveness (SEA) of 35.33 dB, which represents the successful preparation of a type of EMI material following an absorption-dominated mechanism. The CFC-3/PEN-Fe3O4 @PEI-25 demonstrates a satisfying EMI-SE/density/thickness (SSE/t) value of 543 dB·cm2·g−1, higher than most porous polymer-based EMI composites currently. In addition, the mechanical strength of composites is enhanced due to the unique alternating multilayered structure, with the highest tensile strength of 39.03 MPa, which is much higher than the obtained porous PEN membranes via the non-solvent induced phase separation (NIPs) method. This work proposes a novel approach to the construction of lightweight and resistant to secondary contamination ESMs with high performance, exerting enormous potential for wide application.

A laminated carbon nanotubes/silicon boron carbonitride film for high-efficiency electromagnetic interference shielding with oxidation resistance

Constructing layer-structured carbon/ceramic composites is promising for achieving high-performance and high-temperature electromagnetic interference (EMI) shielding materials, in which the rational composition and structural manipulation is critical. Here, a laminated SiBCN@CNTs/SiBCN film with a unique hierarchical structure is prepared using multi-layered carbon nanotubes (CNTs) films as the skeleton by alternatively stacking SiBCN@CNTs layers and SiBCN layers, and its thickness varies from 0.13 to 1.10 mm depending on the number of stacked layers (i.e., 1 to 6 layers) and the concentration of polyborosilazane precursor for impregnation (i.e., 10–70 wt%). Enlarging the thickness of the SiBCN@CNTs layers from 60 to 130 μm in the film or increasing their stacking numbers could both enhance the shielding effectiveness due to the introduction of additional interfacial and interlayer multi-reflection to extend the propagation path of electromagnetic waves for effective wave interference. Consequently, a high EMI shielding effectiveness of 49.4 dB has been achieved on SiBCN@CNTs/SiBCN-50-3, corresponding to a high specific shielding effectiveness (SETotal/d) of 182.9 dB mm−1, higher than previous pure ceramic shielding materials and carbon/ceramic composites. Moreover, because of the effective protection of SiBCN for CNTs, the SETotal of the film is still up to 23.9 dB after oxidation at 1000 °C for 2 h. Therefore, the laminated SiBCN@CNTs/SiBCN film represents an ideal candidate for high-efficiency EMI shielding material used in oxidation environments.

High-strength, flexible and superhydrophobic graphene/aramid nanofiber nanocomposite films for electromagnetic interference shielding application

Electromagnetic interference (EMI) shielding composite materials exhibit many amazing characteristics, including low density, excellent flexibility and corrosion resistance, compared with metals. However, it is a long-standing challenge for EMI shielding materials to overcome inferior mechanical properties and limited hydrophobic characteristics. In this work, the high-strength, flexible and superhydrophobic graphene nanosheet/aramid nanofiber (GNS/ANF) nanocomposite films with layered microstructure were prepared by the sol-gel transformation and spray coating process. The resultant film exhibits excellent mechanical properties with a high tensile strength (131.17 ± 2.77 MPa), large fracture strain (9.58 ± 0.58%), and favorable toughness (8.84 ± 0.74 MJ m−3), which are 26.2 times, 7.5 times and 221.0 times higher than those of pure GNS films. These results are attributed to synergistic effect between intensive stretching of three dimensional (3D) nanofiber network and extensive sliding of GNS produced effective energy dissipation. Moreover, the film with content of 70 wt% GNS has EMI shielding effectiveness of 31.3 dB, and its reflection coefficient is more than 0.89, revealing a reflection-dominant shielding mechanism. Meanwhile, the film possesses superhydrophobic property (158.7° ± 1.1°) and flame retardancy. The multilayered nanocomposite films have excellent potential for high-performance EMI shielding applications under some outdoor conditions.

Superhydrophobic Ti3C2Tx MXene/aramid nanofiber films for high-performance electromagnetic interference shielding in thermal environment

Nowadays, novel two-dimensional (2D) material MXene have attracted extensive interest in the electromagnetic interference (EMI) fields because of outstanding metallic conductivity, unique 2D structure. While it remains a great challenge to construct high-performance EMI shielding MXene-based materials with features of stability and durability and strong mechanical properties. And there are few reports on the evolution of EMI shielding performance of MXene at elevated temperature. Herein, hierarchical structure superhydrophobic Ti3C2Tx MXene/aramid nanofiber (SHMA) films were fabricated by strategy of layer-by-layer construction and their EMI shielding at elevated temperature were investigated. Benefiting from the hierarchical structure, different layers shoulder their independent desired functions, and then work together to ensure that SHMA has high-efficient EMI shielding performance with mechanical stability, moisture stability and thermal stability. Interestingly, the SHMA films exhibited excellent EMI shielding performance with EMI shielding effectiveness (SE) over 49.7 dB at thickness of 70 μm in temperature ranging from 25 to 300 °C. After heat test, the EMI SE of SHMA increased anomalously from 49.7 to 63.2 dB, and the variation of EMI shielding performance and microstructure of SHMA in thermal environment had been intensively investigated and discussed. Moreover, the EMI SE of SHMA was maintained after 6 months and 5 cycles of heating at 300 °C in air. These results indicate great application potential of SHMA as high-performance EMI shielding material in civil, military high-tech equipment and integrated electronics operating in thermal environment.

Magnetic field-induced strategy for synergistic CI/Ti3C2T /PVDF multilayer structured composite films with excellent electromagnetic interference shielding performance

Lightweight, scalable, mechanically flexible conductive polymer composite was always desirable for electromagnetic interference (EMI) shielding applications. In this work, we showcased a novel approach to the superior EMI shielding composite materials by orchestrating the multilayered structure and synergistic system. The asymmetric structure with the carbonyl irons (CI)-rich Ti3C2Tx/poly(vinylidene fluoride) (PVDF) magneto-electric layer jointly behind the Ti3C2Tx nanosheets filled PVDF layer was designed and fabricated with the aid of a facile but efficient magnetic field-induced method and was then hot-pressed into a multilayer structured film. Ti3C2Tx nanosheets were excluded by CI agglomeration layer in the asymmetric film to form the complete 3D electrical conductive skeletons. Based on this strategy, EMI shielding properties of the asymmetric multilayer structured composite was superior to the homogeneous blend and sandwiched or alternating layered composites. In addition, an increase in CI content in the composite referred to the thickening of CI-rich layers, making it gain the most powerful EMI SE values, i.e. 42.8 dB for DCMP20–10 film (20 wt% CI, 10 wt% Ti3C2Tx) at a thickness of 0.4 mm. More importantly, the composite transformed from a reflection type to an absorption dominating EMI shielding material due to the multireflections and magneto-electric synergism in the CI-rich Ti3C2Tx/PVDF layers. Meanwhile, the EMI SE of the composites can be adjusted by increase of either theoverall thickness, or the layer numbers of m-DCMP sheets. The thickness specific EMI SE was calculated as 165.25 dB mm−1 for 4-sheet composite film, a record high value among the high efficiency polymer-based EMI shielding materials. This method offered an alternative protocol for preferential integration of excellent EMI shielding performance with high mechanical performance in CPC materials.

Vertically Aligned Carbon Nanotube@Graphene Paper/Polydimethylsilane Composites for Electromagnetic Interference Shielding and Flexible Joule Heating

High-performance electromagnetic interference (EMI) shielding and thermal management materials with ultraflexibility, high strength, outstanding stability under mechanical deformation, and low cost are urgently demanded for modern integrated electronic and telecommunication systems. However, the creation and application of such desirable materials is still a potent challenge. Herein, we develop such a high-performance multifunctional multilayer composite, known as vertically aligned carbon nanotube@graphene paper/polydimethylsilane (VACNT@GP/PDMS), which involves the in situ growth of VACNTs onto GPs, vertical stacking of VACNT@GP layers, and infiltration of PDMS. The EMI shielding and mechanical properties of multilayer composites can be dramatically increased by increasing the number of VACNT@GP layers. Benefiting from the conduction loss in highly conductive GPs and polarization of huge VACNT–PDMS–VACNT microcapacitor networks, the multilayer composite with four VACNT@GP layers exhibits a superior EMI SE of 106.7 dB over a broad bandwidth of 32 GHz, covering the entire X-, Ku-, K-, and Ka-bands, which far suppresses the values of most of the reported EMI shielding materials. Moreover, the multilayer composites show excellent thermal management performance such as a high Joule-heating temperature at low supplied voltages, rapid response time, and sufficient heating stability. In addition, remarkable flexibility, high tensile strength (up to 13.4 MPa), and super stability under mechanical deformation (nearly no EMI SE degradation after repeatedly bending 10,000 times) are also discovered. These excellent comprehensive properties, along with the ease of low-cost mass production, pave the way for the practical applications of multilayer VACNT@GP/PDMS composites in EMI shielding and thermal management.

Lightweight and hydrophobic Ni/GO/PVA composite aerogels for ultrahigh performance electromagnetic interference shielding

Abstract Lightweight and high-performance electromagnetic interference (EMI) shielding materials are urgently required to solve increasingly serious radiation pollution. However, traditional lightweight EMI shielding materials usually show low EMI shielding performance, poor mechanical properties, and environmental stability, which greatly limit their practical applications. Herein Ni foam/graphene oxide/polyvinyl alcohol (Ni/GO/PVA) composite aerogels were successfully prepared by a freeze-drying method. The Ni/GO/PVA composite aerogels possessed low density (189 mg cm−3) and high compression strength (172.2 kPa) and modulus (5.5 MPa). The Ni/GO/PVA composite aerogel was hydrophobic, and their contact angle can reach 145.2°. The hydrophobic modification improved the environmental stability of the composite aerogels. Moreover, the Ni/GO/PVA composite aerogels exhibited excellent EMI shielding performance. Their maximum EMI shielding effectiveness (SE) can reach 87 dB at the thickness of 2.0 mm. When the thickness is only 1.0 mm, the EMI SE can still reach 60 dB. The electromagnetic energy absorption and attenuation mechanisms of Ni/GO/PVA composite aerogels include multiple reflection and scattering, dielectric loss, and magnetic loss. This work provides a promising approach for the design and preparation of the lightweight EMI shielding materials with superior EMI SE, which may be applied in various fields such as aircrafts, spacecrafts, drones, and robotics.

Excellent electromagnetic interference shielding performance of polypropylene/carbon fiber/multiwalled carbon nanotube nanocomposites

AbstractIn this study, we investigated the mechanical, DC conductivity, and electromagnetic interference (EMI) shielding properties of multiwalled carbon nanotubes (MWCNTs) and carbon fiber reinforced polypropylene (CNC) nanocomposites. The nanocomposites were prepared by melt processing technique using a twin‐screw extruder followed by injection molding. This combination of CF and MWCNT improved the tensile strength and modulus of the nanocomposites by up to 31.14% and 60.14%. The percolation behavior helped to improve the DC electrical conductivity from 2.07 × 10−10 to 9.58 × 10−2 s/cm. The CNC nanocomposites exhibited shielding effectiveness of 51.9 dB at maximum filler loading in the X‐band (8.2–12.4 GHz) for a 2 mm thick sample. In addition, efforts have been made to develop a compatible EMI shielding material using multiple fillers.

Recent Progress in the Application of Cellulose in Electromagnetic Interference Shielding Materials

AbstractExcessive electromagnetic radiation produced by widely used electronic equipment not only harms human health but also affects the accuracy of precision instruments. To meet the growing demand for electromagnetic interference (EMI) shielding materials, various novel materials are investigated. As a natural biopolymer, cellulose possesses the merits of biodegradability, thermal stability, easy processability, and low cost. Owing to tremendous advantages, cellulose can be used as a substrate, binder, and derived carbon material for EMI shielding materials. Although many research papers on EMI shielding materials containing cellulose have been published, a detailed summary on them has not been acknowledged yet. Hence, this review is composed mainly to cover the structure and properties of cellulose, as well as electromagnetic shielding theory, which are explained in detail by using various research articles, review papers, and book chapters. And the recent applications of cellulose in EMI shielding materials are highlighted. It is hoped that the information gathered from previous studies can provide a reference for the fabrication of cellulose composites with higher EMI shielding performance in future research.