Electromagnetic Interference Shielding Effectiveness Research Articles

Scalable production of polyamide-6/graphene composites with enhanced electromagnetic shielding and thermal conductivity

Composites with thermal management (TM) capability and electromagnetic interference (EMI) shielding effect are in high demand for miniaturization and modernization of electronics. However, achieving both of these properties simultaneously by constructing a dense conductive network within the polymer matrix is a very big challenge. Herein, a fully scalable and sustainable production process for polyamide-6/few layer graphene (PA-6/FLG) with vigorous dispersion of FLG in the PA-6 matrix was demonstrated by combining mechanochemistry with supercritical CO2 (scCO2) technology. By this process, the bulk graphite was rapidly cleaved into a FLG (≈10 layers), which was completely coated onto the spherical PA-6 particles. The composite films of this coated powder with only 3 wt% FLG loading amount attained wonderful in-plane electrical conductivity (IP-σc) and through-plane electrical conductivity (TP-σc) of 4.59 S·m−1 and 29.59 S·m−1, respectively, and outstanding EMI shielding effect of 41.8 dBs. In addition, the in-plane thermal conductivity (IP- kc) and the through-plane thermal conductivity (TP- kc) were 1.78 W m−1 K−1 and 2.14 W m−1 K−1 respectively. Therefore, the films rapidly dissipate heat from an electronic LED chip. Moreover, PA-6/FLG composite filaments showed a smooth appearance and an electrical resistivity of 7.12 GΩ. This work has strong potential to improve the performance of different polymer/graphene composites and expand their applications.

Carbon composite foams from the wasted banana leaf for EMI shielding and thermal insulation

Low-density fire-resistant materials with high EMI shielding effectiveness and low thermal conductivity are extremely important in aerospace and defence applications. Utilization of agricultural residues for achieving this reduces CO2 emission as well as produces wealth for the farmers. Herein, a fibre extracted from the wasted matured banana leaf by a simple chopping and grinding using a mixture-grinder is used for the preparation of carbon composite foams. The banana leaf fibres dispersed in sucrose solution are consolidated by filter-pressing followed by freeze drying to produce banana leaf fibre-sucrose composites. The carbon produced from sucrose during carbonization binds the carbonized banana leaf fibre to produce the carbon composite foams. The XRD pattern and Raman analysis indicated the turbostratic nature of the carbon, and XPS analysis shows the presence of oxygen-containing functional groups. The textural property measurement and TEM analysis indicated the presence of micro and meso pores in the carbon composite foams. The foam density (0.14–0.28 g cm−3), compressive strength (0.14–0.88 MPa), electrical conductivity (3.7–8.7 S m−1), and thermal conductivity (0.095–0.144 W m-1 K−1) of the carbon composite foams increases with an increase in sucrose solution concentration (300–700 g L−1). The carbon composite foams exhibit a reflection-dominated EMI shielding with high total shielding effectiveness in the range of 48.3–77.5 dB. The multiple internal reflections within a range of macropores available in the carbon composite foams, leading to enhanced absorption, are responsible for the excellent EMI shielding characteristics.

Self-Assembling Ultrathin MXene/Cellulose Nanofiber/MXene Composite Film for High-Performance Electromagnetic Interference Shielding

Ti3C2T[Formula: see text] MXene films exhibited good electromagnetic interference (EMI) shielding performance. However, the poor mechanical property and durability of Ti3C2T[Formula: see text] MXene films limited their commercial application. Herein, the ultrathin flexible conductive MXene/cellulose nanofiber (CNF)/MXene composite films with “sandwich” structure were successfully prepared by a simple vacuum-assisted filtration process. The addition of CNF can shield more electromagnetic microwaves (EMWs) via multiple reflections in the inner space and enhance the mechanical property of composite films by effectively welding the loosely MXene together. The composite film exhibited excellent EMI shielding effectiveness (up to 54.68 dB) at an ultrathin thickness (about 76 [Formula: see text]m) as well as high electrical conductivity (up to 1610.51 S/m), which was mainly attributed to the hierarchical lamellar “sandwich” structure, where CNF was bonded to Ti3C2T[Formula: see text] MXene. The prepared flexible conductive composite films with brilliant EMI shielding effectiveness and good mechanical property possessed promising potential in various fields such as electromagnetic wave protection, weaponry and wearable electronics.

Heterogeneous Waterborne Polyurethane Composite with Alternating Electromagnetic Layers for Absorption-Dominated Electromagnetic Interference Shielding.

Flexible waterborne polyurethane (WPU) electromagnetic interference (EMI) composites of heterogeneous alternating multilayer structure with conductive gradient were fabricated through the layer-by-layer stacking and hot-pressing methods. Combining the synergetic electromagnetic loss and interface polarization loss formed by the selective distribution of metallized chopped polyimide fiber (PI@Ni/Cu/Ni), reduced graphene oxide (rGO), and magnetic Fe3O4 fillers, as well as multilevel electromagnetic wave propagation paths, the penetrating microwaves would undergo a particular "absorption-reflection-reabsorption" process in the composite. The asymmetric multilayer WPU composite with an absorption-dominated shielding feature exhibits a high EMI shielding effectiveness (SE) of 53.90 dB and an A value of 0.56. Moreover, the multilayer WPU composite maintains excellent integrity through repeating bending, long-time soaking, and burning tests. This work provides a viable strategy for the design of absorption-dominated EMI shielding material with controllable and stable performance that is befitting for next-generation advanced electronic products.

Electromagnetic interference shielding effects of modified carbon nanotube-nylon 12 composite films

ABSTRACT Metal-based electromagnetic interference shielding materials are limited in their application due to their susceptibility to corrosion. They are therefore being replaced by corrosion-resistant polymers and carbon nanotubes. However, it is difficult to disperse carbon nanotubes within polymer matrices as they aggregate because of van der Waals forces. Therefore, to improve the dispersion of carbon nanotubes, we modified thin-wall carbon nanotubes with flavin mononucleotides and tested them by manufacturing a polymer composite. Nylon 12 was chosen as the polymer matrix owing to its excellent abrasion resistance and low wettability. Furthermore, upon annealing the modified carbon nanotubes, the tensile strength of the composite and dispersion after modification increased. When 10 wt% of the annealed modified nanotubes was used, the composite exhibited a sheet resistance of 8.7 Ω/sq and an EMI shielding effectiveness of 29.4 dB in the X-band. The novel composite can be advantageous for use in electronic equipment due to its low weight and flexibility.

Robust multifunctional composite films with alternating multilayered architecture for highly efficient electromagnetic interference shielding, Joule heating and infrared stealth

Developing ultrathin electromagnetic interference (EMI) shielding materials with high-efficiency EMI shielding effectiveness (SE), anisotropic thermal conductivity and robust mechanical performance is urgently required but challenging to satisfy the integration and miniaturization of modern flexible electronics. Herein, an alternating multilayered film containing alternating CoFe2O4@MXene/cellulose nanofibers (CNF) layers and silver nanowires (AgNWs)/CNF layers was successfully fabricated via a facile alternating vacuum-assisted filtration strategy. Profiting from the rational arrangement of CoFe2O4@MXene/CNF layers and AgNWs/CNF layers, electric/magnetic coupling effect and unique “absorption-reflection-reabsorption” shielding behavior among the alternating multilayered films, the resultant composite film with alternating six-layered architecture realizes an ultra-high EMI SE of 87.8 dB with low electromagnetic waves reflection effectiveness of 5.6 dB at a thickness of only 0.1 mm. The film remains reliable EMI shielding performance (over 97% EMI SE retention) after undergoing persistently physical damage and prolonged chemical attack. Meanwhile, owing to the construction of overlapping AgNWs network, the obtained film acquires outstanding in-plane thermal conductivity (6.875 W/(m·K)) and controllable Joule heating performance (steady temperature over 90 °C at applied voltage of 3.0 V within 20 s). The inferior through-plane thermal conductivity (0.689 W/(m·K)) caused by the design of multilayered structure guarantees the remarkable infrared stealth performance. Additionally, the good interfacial interaction endows the prepared film with robust mechanical properties (tensile strength of 183.2 MPa and fracture strain of 5.4%). This work not only offers a creative avenue for designing and preparing multifunctional EMI shielding composite films with excellent mechanical properties, but also broadens the applications of EMI shielding composite films in military fields, artificial intelligence and wearable electronics.

Appraising the dielectric properties and the effectiveness of electromagnetic shielding of graphene reinforced silicone rubber nanocomposite

Abstract The aim of this research is to measure the dielectric properties and electromagnetic interference (EMI) shielding effectiveness (SE) of silicone rubber reinforced with graphene nanoplates. In a two-roll mill, different amounts of graphene are mixed together. This is followed by compression moulding at 170°C and post-curing for 4 h at 200°C. Between 1 MHz and 1 GHz, the waveguide transmission line method and a vector network analyser are used to measure the dielectric and EMI SE parameters. As the amount of graphene is increased from 0 to 7 wt%, AC conductivity goes up, reaching 1.19 × 10−3 S/cm at 7 wt%. The same composition gives the highest EMI SE of 43.22 dB at 1 GHz. The high-frequency structural simulation of different compositions shows how shielding works, and the results agree with what has been seen in experiments.

Highly fire safe and flexible nanoarchitectures with tunable interface towards excellent electromagnetic interference shielding

To meet the demand for practical applications, it is imperative to develop flexible electromagnetic interference (EMI) shielding materials with fire safety. In this work, highly fire safe and flexible thermoplastic polyurethane (TPU)-based EMI shielding nanocomposites were prepared via melt blending polyphenyl phosphate ester amide (PPPEA) with MXene/carboxylic multiwalled carbon nanotubes hybrid (MC), air-assisted thermocompression and layer-by-layer stacking. Combining PPPEA with MC led to peak of heat release rate, total heat release and total smoke release of TPU nanocomposite containing 5.0 wt% PPPEA and 2.0 wt% MC decreased by 39.0%, 24.5% and 23.8%, respectively. Furthermore, the hierarchical TPU/5PA/2.0MC/carbon fiber cloth (CF) nanocomposite showed a prominent averaged EMI shielding effectiveness (SE) of 35.5 dB and a high normal SE value of 29.6 dB/mm, which were superior to most previously reported results. Catalytic carbonization of PPPEA and multiply reflected and scattered effect of MC together with continuous conductive network of CF were responsible for the improvement of these performances.

Fabrication of Flexible FCI/PDMS Electromagnetic Shielding Composites Based on Pulsed Magnetic Field-Induced Alignment

Conductive polymer composites have been utilized in the field of electromagnetic interference (EMI) shielding, albeit requiring a high concentration of conductive fillers to achieve desirable EMI performance. To address this issue and enable the creation of superior EMI shielding composites with reduced filler loadings, this study employed a pulsed magnetic field featuring an amplitude of 0.7 T, a pulse width of 10 μs, and a frequency of 100 Hz to align flaky carbonyl iron (FCI) in poly(dimethylsiloxane) (PDMS). This method resulted in an improved EMI shielding performance of the composites. The outcomes revealed that the pulsed magnetic field effectively controlled the orientation of the FCI, forming a conductive network structure, with the average orientation angle of the FCI reaching 69.3°. The aligned composites exhibited a significant improvement in EMI shielding effectiveness, with the enhancement effect reaching 37.53% and the EMI shielding effectiveness reaching 24.87 dB. Moreover, the flexible tensile properties of the aligned composites were superior to those of the unaligned composites, particularly the elongation at break, which reached 197.46%. The concordance between the theoretical analysis and experimental results affirms the efficacy of the microsecond pulsed magnetic field in enhancing the EMI shielding performance of composite materials. Ultimately, the high-performance, flexible electromagnetic shielding composite materials prepared in this study demonstrate potential for use in advanced electronic equipment.

Electromagnetic Interference Shielding Performances of Carbon-Fiber-Reinforced PA11/PLA Composites in the X-Band Frequency Range.

To solve the problem of increasing electromagnetic pollution, it is crucial to develop electromagnetic interference (EMI) shielding materials. Using lightweight, inexpensive polymeric composites instead of currently used metal shielding materials is promising. Therefore, bio-based polyamide 11/poly(lactic acid) composites with various carbon fiber (CF) amounts were prepared using commercial extrusion and injection/compression molding methods. The prepared composites' morphological, thermal, electrical conductivity, dielectric, and EMI shielding characteristics were investigated. The strong adhesion between the matrix and CF is confirmed by scanning electron microscopy. The addition of CF led to an increase in thermal stability. As CFs formed a conductive network in the matrix, direct current (DC) and alternative current (AC) conductivities of the matrix increased. Dielectric spectroscopy measurements showed an increase in the dielectric permittivity/energy-storage capability of the composites. Thus, the EMI shielding effectiveness (EMI SE) has also increased with the inclusion of CF. The EMI SE of the matrix increased to 15, 23, and 28 dB, respectively, with the addition of 10-20-30 wt % CF at 10 GHz, and these values are comparable or higher than other CF-reinforced polymer composites. Further analysis revealed that shielding was primarily accomplished by the reflection mechanism similar to the literature data. As a result, an EMI shielding material has been developed that can be used in commercially practical applications in the X-band region.

High-performance flexible nanocomposites with superior fire safety and ultra-efficient electromagnetic interference shielding

High-performance multifunctional polymeric materials integrated with high fire safety, excellent mechanical performances and electromagnetic interference (EMI) shielding properties have great prospects in practical applications. However, designing highly fire-safe and mechanically robust EMI shielding nanocomposites remains a great challenge. Herein, hierarchical thermoplastic polyurethane/cyclophosphazene functionalized titanium carbide/carbon fiber fabric (TPU/CP-Ti3C2Tx/CF) nanocomposites with high fire safety and mechanical strength and toughness were prepared through the methods of melt blending, layer-by-layer stacking and thermocompression. The TPU/CP-Ti3C2Tx showed improved thermal stability. Moreover, the peak of heat release rate and total heat release of the hierarchical TPU sample containing 4.0 wt.% CP-Ti3C2Tx were respectively reduced by 64.4% and 31.8% relative to those of pure TPU, which were far higher than those of other TPU-based nanocomposites. The averaged EMI shielding effectiveness value of the hierarchical TPU/CP-Ti3C2Tx-2.0/CF nanocomposite reached 30.0 dB, which could satisfy the requirement for commercial applications. Furthermore, the tensile strength of TPU/CP-Ti3C2Tx-2.0/CF achieved 43.2 MPa, and the ductility and toughness increased by 28.4% and 84.3% respectively compared to those of TPU/CF. Interfacial hydrogen bonding in combination with catalytic carbonization of CP-Ti3C2Tx nanosheets and continuous conductive network of CF were responsible for the superior fire safety, excellent EMI shielding and outstanding mechanical performances. This work offers a promising strategy to prepare multifunctional TPU-based nanocomposites, which have the potential for large-scale application in the fields of electronics, electrical equipment and 5 G facilities.

Ultrathin multifunctional electromagnetic interference shielding MXene/AgNWs/PEDOT:PSS coatings with superior electro/photo-thermal transition ability and water repellency

Harsh freezing and high-humidity environments lay down paramount bottlenecks for the utilization prospect of polymeric electromagnetic interference (EMI) shielding materials. Herein, ultrathin and flexible multifunctional EMI shielding MXene/Ag nanowires/poly(3, 4-ethylene dioxythiophene):polystyrene sulfonate (MXene/AgNWs/PEDOT:PSS) composite coatings were fabricated via the facile drop-casting of MXene/AgNWs/PEDOT:PSS mixture dispersion and subsequent hydrophobic spraying modification. Profited by the superior electrical conductivity of both polymer host and filler guests, MXene/AgNWs/PEDOT:PSS coatings exhibit the preeminent EMI shielding effectiveness (SE) of 31.5 dB at a rather small thickness of 10 µm, far surpassing that of most the reported polymer-based EMI shielding composites at the similar thickness. Moreover, MXene/AgNWs/PEDOT:PSS coatings also hold excellent electro/photo-thermal transition ability and fascinating water repellency, which ensures their normal application on cold and damp conditions. Interestingly, the intensive interlocking effect of 1 D AgNWs and 2 D MXene allows the wonderful interfacial adhesion and mechanical durability of MXene/AgNWs/PEDOT:PSS coatings. This study provides a valuable insight into the design and construction of multifunctional polymeric coatings for EMI shielding of high-power and high-frequency electronics in cold and high-humidity environments.

Conducting Polymer Nanocomposites for Electromagnetic Interference Shielding—Radical Developments

Electromagnetic interference disturbs the working of electronic devices and affects the surroundings and human health. Consequently, research has led to the development of radiation-protection materials. Inherently conducting polymers have been found to be suitable for electromagnetic interference (EMI) shielding owing to their fine electrical conductivity properties. Moreover, nanoparticle-reinforced conjugated polymers have been used to form efficient nanocomposites for EMI shielding. Nanoparticle addition has further enhanced the radiation protection capability of conducting polymers. This state-of-the-art comprehensive review describes the potential of conducting polymer nanocomposites for EMI shielding. Conducting polymers, such as polyaniline, polypyrrole, and polythiophene, have been widely used to form nanocomposites with carbon, metal, and inorganic nanoparticles. The EMI shielding effectiveness of conducting polymers and nanocomposites has been the focus of researchers. Moreover, the microscopic, mechanical, thermal, magnetic, electrical, dielectric, and permittivity properties of nanocomposites have been explored. Electrically conducting materials achieve high EMI shielding by absorbing and/or dissipating the electromagnetic field. The future of these nanomaterials relies on nanomaterial design, facile processing, and overcoming dispersion and processing challenges in this field.

Bacterial-Cellulose-Reinforced Graphite Nanoplate Films for Electromagnetic Interference Shielding, Heat Conduction, and Joule Heating

With the flourishing development of wireless communication, there is an urgent need for flexible and robust materials with excellent thermal conductivity (TC) and electromagnetic interference (EMI) shielding performance through simple and green preparation. In this work, we efficiently prepared bacterial-cellulose-reinforced graphite nanoplate (BC-GNP) composite films by the vacuum filtration of BC/GNP mixture dispersions. Compared with the pure GNP film with a loose and disordered structure, the BC-GNP composite showed a highly aligned and compact “brick-and-mortar” structure. Benefiting from the unique structure, the resultant BC-GNP with 20 wt % BC (20%BC) exhibited a high tensile strength of 47.3 ± 1.8 MPa and an electrical conductivity of 76.9 ± 3.3 S/cm. As expected, the 20%BC showed excellent EMI shielding effectiveness (EMI SE) of 36.4 dB and a specific EMI SE (SSE/t) value of 8860 ± 400 dB·cm2/g with a thickness of 38 ± 1 μm. The in-plane TC and anisotropy index could reach up to 80.2 ± 6.4 W/mK and 73 ± 3, respectively. The 20%BC also exhibited a satisfactory Joule heating performance of 139 °C at a voltage of 6 V. More importantly, the 20%BC possessed a biodegradable property, which would completely degrade after 5 days. Thus, this work provides a strategy to facilely prepare biodegradable, high-performance, and multifunctional materials for wearable devices.

Multifunctional composite foam with high strength and sound‐absorbing based on step assembly strategy for high performance electromagnetic shielding

AbstractSoft polyurethane (PU) materials exhibit excellent structural stability, sound absorption and heat insulation, and they can be used to prepare multifunctional conductive composites with electromagnetic interference (EMI) shielding function. On the basis of a multistep assembly strategy, our study constructed composite foams with sound absorption and EMI shielding properties by designing different functional layers and expanded the application field of PU foam. First, carbon black particles are compounded with PU foam to improve the mechanical properties and conductivity of pure foam. Then, an aluminum layer and a knitted fabric layer were introduced to construct composite foam samples with a sandwich structure, endowing the materials with excellent EMI shielding performance. The resultant composite foam material exhibits effective EMI shielding performance and good sound absorption performance, which are 58.33 dB and >0.3, respectively. Moreover, the composite foam material demonstrates high bursting strength and compression resistance, suggesting that it can be used under different conditions. The employment of the multistep assembly strategy provides PU foam with a flexible range of applications, offering an innovative approach for preparing multifunctional conductive composite materials.

Free-standing polymer/multiwalled carbon nanotubes composite thin films for high thermal conductivity and prominent EMI shielding

Lightweight composite materials with efficient thermal conductivity (TC) and high electromagnetic interference (EMI) shielding effectiveness (SE) are of paramount importance for a wide range of applications such as electronics, aerospace, and stealth technology. In this work, lightweight, flexible, and free-standing poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/multiwalled carbon nanotube (MWCNT) composite thin films are fabricated by a single-step, solution casting method. Fabricated PVDF-HFP/MWCNT composite thin films are characterized by many physicochemical techniques such as Raman spectra, Fourier transform infrared spectra, X-ray diffractometer, and high-resolution transmission electron microscope. The resulting composite thin film exhibits a TC of 1.1 Wm−1K−1 at room temperature. Further analysis shows that the TC of the composite film is increased up to 1.8 Wm−1K−1 at 100 °C. As fabricated flexible and free-standing composite thin film (thickness ∼ 150 µm) exhibit an excellent EMI SE of ∼ 36 dB in the X-band region (8.2–12.4 GHz) at just 15 wt. % loading of MWCNT. The outstanding EMI shielding and high TC of PVDF-HFP/MWCNT composite films are attributed to the homogenous distribution and well-connected network of MWCNT within the polymer matrix, forming a conductive network throughout the composite film.

Effect of carbon fiber reinforcement on the mechanical and electromagnetic shielding properties of the Fe3O4‐carbonaceous/epoxy composites

AbstractThe present work aimed at the simultaneous improvement in the mechanical and electromagnetic shielding properties of Fe3O4‐carbonaceous/epoxy composites by the reinforcement of two plies of carbon fiber into the epoxy‐filler matrix. In this study, Fe3O4‐activated carbon and Fe3O4‐activated charcoal composites were synthesized by co‐precipitation method and were introduced into the epoxy matrix with different weight percentage (5, 10, and 15 wt%). The BET surface area analysis revealed the high porosity in the Fe3O4‐activated charcoal composite than that of activated carbon composite. The Fe3O4‐activated carbon/epoxy composite showed better mechanical properties than the later. Both the composites showed nearly same EMI SE value. 10 wt% of the filler‐1/epoxy composite showed the highest shielding effectiveness (SE) value of −22.5 dB at 10 GHz whereas 15 wt% Fe3O4@charcoal/epoxy composite showed better SE value of −27.15 dB at 8.8 GHz. The obtained results were supported by the dielectric and magnetic loss tangent studies. The incorporation of carbon fiber enhanced the mechanical property by three times and the EMI SE value by ~15 dB. Thus, the carbon fiber reinforced Fe3O4/carbonaceous epoxy composites may be the potential electromagnetic shielding material for electronics and aircraft industries.

Maximized internal scattering in heterostack Ti3C2T x MXene/graphene oxide film for effective electromagnetic interference shielding

Two-dimensional (2D) MXenes have attracted significant attention in electromagnetic interference (EMI) shielding applications due to their excellent metallic conductivity, high surface area, 2D geometry, tunable surface chemistry, and solution processability. In this study, we present a straightforward way of introducing multiple nanoscale interfaces into Ti3C2T x MXenes using insulating graphene oxide (GO) intercalants to enhance internal scattering, resulting in improved EMI shielding effectiveness (SE). The amine-functionalized MXene with positive surface charge and negatively charged GO flakes are electrostatically self-assembled to form a 2D/2D heterostack of MXene/GO nanosheets. The resultant 2D/2D alternating heterostack of MXene/GO bearing multiple internal interfaces with significant impedance mismatch enhances the internal scattering of incident electromagnetic (EM) waves. Interestingly, despite their inferior electrical conductivity, the MXene/GO heterostack films exhibit higher EMI SE values than the randomly mixed hybrid films, and even outperform pristine MXene films. These MXene/GO heterostack films with enhanced absorption of EM waves via the strong internal scattering effect suggest a valuable pathway toward practical EMI shielding with thin and lightweight features.

Incorporation of FexOy nanoparticles into 3D interlinked porous carbon nanofiber networks to synergistically enhance the electrical insulation, electromagnetic wave absorbing/shielding performance and thermal conductivity

The property incompatibility among heat conduction, electromagnetic wave (EMW) absorption/shielding, and electrical insulation has restricted the synchronous enhancement and application of polymer-based composites. Herein, we first synthesized porous 3D interlinked C nanofiber/FexOy (CNF/FexOy) wafers for significantly enhanced properties by a simple sol–gel and annealing route. The texture, composition, defects and the resulting properties can conveniently be manipulated via altering Fe3+ concentration and annealing temperature. The CNF/FexOy wafers exhibit a high heat conductivity (3.22 W/mK) at a low loading (30 wt%) thanks to the shorter continuous thermal transfer paths and the increased phonon mean free path and thermal capacity of phonons per volume. Moreover, CNF/FexOy wafers possess a wide absorption band (9.36 GHz), prominent EMI shielding effectiveness (SET ≥ 20 dB over C, X, and Ku bands), excellent electrical insulation (σ = 0.00991 S/m), and enhanced mechanical/hydrophobicity properties, surpassing most reported fillers. These enhancements could be explained by the fact that the cooperative action of porous structures, defects, and magnetic/dielectric FexOy hinder electron migration and improve the impedance matching and multiple-scattering of materials. The silicone composites supported by 3D interlinked CNF/FexOy wafers have great potential as a filler with high-performance EMI shielding/absorption and thermal control in next-generation flexible electronics.

Model of electromagnetic interference shielding effectiveness for a multifunctional composite containing carbon-fiber-reinforced polymer and copper mesh layers

A multifunctional composite structure consisting of a carbon-fiber-reinforced polymer (CFRP) laminate with additional Cu mesh layers was investigated for use as an electromagnetic interference (EMI) shield in aerospace applications. The Cu mesh layers were added to increase EMI shielding effectiveness (SE) of the structure. A finite element model of EMI SE was constructed to predict SE in the radiofrequency to microwave range for different laminate lay-ups. It was found that the SE of the CFRP layers was improved by including plies with different relative fiber orientations. Further, the combination of CFRP layers, which primarily shield by absorption, and Cu mesh, which predominantly shields by reflection, provided adequate SE over a wider frequency range than the individual components alone due to the opposing trends of increasing absorption loss (CFRP component) and decreasing reflection loss (copper mesh) with increasing frequency.