Effective Electromagnetic Interference Shielding Materials Research Articles

Anisotropic high-strength polyimide-based electromagnetic interference shielding foam based on cation-π interaction

Effective electromagnetic interference (EMI) shielding plays a vital role in numerous applications by mitigating the detrimental impacts of electromagnetic waves. In this study, we developed a novel anisotropic MXene@PI hybrid foam for efficient EMI shielding using a synergistic approach involving directional freezing, freeze-drying, thermal imidization, and a subsequent dip-coating step. The cation-π interaction was harnessed to create a crosslinked structure for enhancing the mechanical properties of the polyimide (PI) foam and also to improve the interfacial interaction between MXene and the inner wall of the foam. The foam exhibited a tubular structure in a vertical frozen direction while adopting a honeycomb-like structure in a parallel freezing direction. The anisotropic MXene@PI-5 hybrid foam demonstrated remarkable EMI shielding effectiveness of up to 62.7 dB in the vertical freezing direction, 158.02 % higher than that observed in the parallel direction, and 109.70 % higher than that in the isotropic foam with the same loading of MXene. This anisotropic MXene@PI hybrid foam offers great potential for applications requiring efficient EMI shielding, such as aerospace, electronics, telecommunications, etc. The unique combination of the cation-π interaction and anisotropic structure provides enhanced EMI shielding properties, making it a promising candidate for future EMI shielding materials.

Tailored distribution of 1D nanoparticles in co-continuous EMA/TPO flexible polymeric blends used as emerging materials for suppressing electromagnetic radiation

Electromagnetic interference (EMI) is unwanted noise or interference that often affects electronic equipment and human health. An effective EMI shielding material is needed to protect electronic equipment and human health to block EMI signals. In this work, we have developed electrically conductive polymer composites via the preferential localization of MWCNTs in a co-continuous ethylene-co-methyl acrylate (EMA)/thermoplastic polyolefin (TPO) (80/20 w/w) binary blend system using a solution mixing technique. The electrical percolation threshold was achieved by incorporating 3 to 5 wt% of MWCNT in the blend matrix. FESEM and TEM images indicated a co-continuous morphology in which MWCNT was thermodynamically and kinetically driven into the EMA phase of the polymer blend. The DC and AC conductivity of the fabricated composite was significantly increased upon loading the MWCNT in the polymer composite. A total EMI shielding effectiveness of −35 dB was achieved by adding 15 wt% MWCNT into the matrix in the frequency range of 14.5–20.0 GHz, along with good thermal conductivity, dielectric properties, and mechanical properties.

Layered polymer composite foams for broadband ultra-low reflectance EMI shielding: a computationally guided fabrication approach.

The development of layered polymer composites and foams offers a promising solution for achieving effective electromagnetic interference (EMI) shielding while minimizing secondary electromagnetic pollution. However, the current fabrication process is largely based on trial and error, with limited focus on optimizing geometry and microstructure. This often results in suboptimal electromagnetic wave reflection and the use of unnecessarily thick samples. In this study, an input impedance model was employed to guide the fabrication of layered PVDF composite foams. This approach optimized the void fraction (VF) and the thickness of each layer to achieve broadband low reflection. Moreover, hybrid heterostructures of SiCnw@MXene were incorporated into the PVDF composite foams as an absorption layer, while the conductive PVDF/CNT composite foams served as a shielding layer. Directed by theoretical computations, we found that combining 2.2 mm of PVDF/SiCnw@MXene composite foam (50% VF) and 1.6 mm of PVDF/CNT composite yielded EMI shielding effectiveness of 45 dB, with an average reflectivity (R) of 0.03 and an effective absorption bandwidth of 5.54 GHz (for R < 0.1) over the Ku-band (12.4-18 GHz). Importantly, the corresponding peak R was only 0.000017. Our work showcases a theoretically guided approach for developing absorption-dominant EMI shielding materials with broadband ultra-low reflection, paving the way for cutting-edge applications.

A review on efficient electromagnetic interference shielding materials by recycling waste-a trio of land to lab to land concept.

The materials used in electrical and electronic applications have great importance and broader applications, but they have severe electromagnetic interference (EMI). These materials have extensive applications in broadcasting, medical industries, research, defence sectors, communication and similar fields. The EMI can be addressed by using effective EMI shielding materials. This review presents a detailed, comprehensive description for making electromagnetic interference shielding material by recycling various wastes. It starts with highlighting the overview of electromagnetic interference shielding (EMI) and its theoretical aspects. It provides a comprehensive and detailed understanding of recent trends in the novel approaches towards fabricating EMI shielding from industrial waste, agricultural waste and other miscellaneous wastes. This paper critically reviews the works related to the recycling of wastes like red mud (waste from the aluminium refining industry), ground tyre rubber, tea waste (biowaste) from tea industries, bagasse (waste from sugar cane industry), peanut and hazelnut shells (agricultural waste), waste tissue paper and polyethylene and other miscellaneous wastes like hydrocarbon carbon black and ash for the fabrication of highly effective electromagnetic (EM) interference shielding materials. Highly effective results have been reported using red mud showing maximum efficiency of 51.4 dB in X-band range, various agricultural waste displaying reflection loss of up to - 87.117 dB (in the range 0.01 to 20 GHz) and miscellaneous waste giving EMI SE of 80 dB in X-band frequency. A separate section is dedicated to emphasizing future work and recommendations.

Structural, dielectric and EMI shielding properties of polyvinyl alcohol/chitosan blend nanocomposites integrated with graphite oxide and nickel oxide nanofillers

Polyvinyl alcohol (PVA) and Chitosan (CS)-based novel composites were prepared using solution casting technique by introducing graphite oxide (GO) and nickel oxide (NiO) as nanofillers. The structural, thermal and mechanical properties of PVA/CS/GO/NiO nanocomposites were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The dielectric and electromagnetic interference (EMI) shielding properties of synthesized nanocomposites were also investigated. The addition of dual nanofillers in the PVA/CS blend resulted in improved thermal stability of nanocomposites through the interaction of nanofillers with OH groups of polymer matrices. The DMA results displayed higher storage and loss modulus at low temperature for nanocomposite with 1.5/15 wt% of GO/NiO loading. The maximum values of dielectric constant and dielectric loss obtained are 1315.5 and 11.1 at the low-frequency region, respectively. The absorption dominated EMI shielding effectiveness (SE) was observed with a maximum EMI SE value of 12 dB for nanocomposite film containing 3.0/30 wt% of GO/NiO as compared to EMI SE value of 0.3 dB for PVA/CS blend in Ku-band (12–18 GHz) region. The electrical network formation by GO and NiO in the polymer matrix resulted in an improved EMI SE which further emphasizes the potential use of these nanocomposite films as an effective EMI shielding material.

High temperature electromagnetic interference shielding of lightweight and flexible ZrC/SiC nanofiber mats

SiC based materials are ideal candidates for electromagnetic-interference (EMI) shielding application at high temperature. Herein, lightweight and flexible ZrC/SiC hybrid nanofiber mats were successfully fabricated by electrospinning and high temperature pyrolysis with polycarbosilane (PCS) and Zirconium acetylacetone ((Zr(acac)3) as precursors. The adding of Zr(acac)3 makes the PCS solution a lower viscosity and higher conductivity. After pyrolysis, highly conductive ZrC nanoparticles are uniformly distributed in the SiC nanofiber matrix. As a result, the average diameter of ZrC/SiC nanofibers is reduced from 2.6 μm to 330 nm compared with pure SiC fibers. Meanwhile, the specific BET surface area (SBET) of ZrC/SiC nanofiber mat is also improved from 51.5 to 131.1 m2/g due to the reduced diameter and rough surface morphology. Meanwhile, the electrical conductivity of ZrC/SiC nanofiber mat greatly rises from 1.5 × 10−6 to 1.3 × 10−1 S/cm. It is found that 3-layer ZrC/SiC naofiber mats with the total thickness of 1.8 mm achieve the EMI shielding effectiveness (SET) of 18.9 dB. With a low density of 0.06 g/cm3, the specific shielding effectiveness could be as high as 315 dB·cm3·g−1. Moreover, the SET value could be further promoted to 20.1 dB at 600 °C. Such optimized EMI shielding performance indicates that the ZrC/SiC nanofiber mat could be an excellent lightweight and effective EMI shielding material for high temperature application.

Mechanically robust ANF/MXene composite films with tunable electromagnetic interference shielding performance

MXene-based materials have been widely studied recently for effective electromagnetic interference (EMI) shielding due to the prominent intrinsic electrical conductivity. Nevertheless, the poor mechanical performance of pure MXene films limits the practical application in EMI shielding. Thus, we integrate MXene with aramid nanofiber (ANF) to develop a composite film with layered structure through a simple vacuum-assisted filtration method. The resulting ANF/MXene (20/80) composite exhibits a high electrical conductivity of 879.0 S/cm, EMI shielding effectiveness (SE) of 40.6 dB and specific SE (SSE/t, SE divided by the density and thickness) of 50,491 dB∙cm2∙g−1 with an ultrathin thickness of 3.2 μm. Furthermore, the ANF/MXene (60/40) realizes a balance between mechanical properties and EMI shielding performance with the strength of 201.3 MPa and SE of 28.1 dB, which enables the ANF/MXene composite films as promising EMI shielding materials with excellent mechanical robustness.

Recent Advancement of Electromagnetic Interference (EMI) Shielding of Two Dimensional (2D) MXene and Graphene Aerogel Composites.

The two Dimensional (2D) materials such as MXene and graphene, are most promising materials, as they have attractive properties and attract numerous application areas like sensors, supper capacitors, displays, wearable devices, batteries, and Electromagnetic Interference (EMI) shielding. The proliferation of wireless communication and smart electronic systems urge the world to develop light weight, flexible, cost effective EMI shielding materials. The MXene and graphene mixed with polymers, nanoparticles, carbon nanomaterial, nanowires, and ions are used to create materials with different structural features under different fabrication techniques. The aerogel based hybrid composites of MXene and graphene are critically reviewed and correlate with structure, role of size, thickness, effect of processing technique, and interfacial interaction in shielding efficiency. Further, freeze drying, pyrolysis and hydrothermal treatment is a powerful tool to create excellent EMI shielding aerogels. We present here a review of MXene and graphene with various polymers and nanomaterials and their EMI shielding performances. This will help to develop a more suitable composite for modern electronic systems.

Effect of conducting fillers in natural rubber nanocomposites as effective EMI shielding materials

An economical and effortless method for the production of flexible shielding material for feasible application has gained remarkable attention since the massive spread of technologies has notably marked up the electromagnetic pollution, which will cause interference or malfunctioning of electronic devices. Traditionally Electromagnetic Interference (EMI) shielding is achieved by using a metal screen to absorb it. But metals have low impact resistance, high density and are susceptible to corrosion, polymer nanocomposites with magnetic nanofillers become a radical alternative to this. Rubber based nanocomposites have considerable importance since they bear excellent multifunctional applications. The conductive fillers incorporated in the polymer matrix give out the advance functions like light weight, corrosion resistance and tailored coefficient of thermal expansion and ease of processing. In the class of magnetic materials that possess broad applications in technology, Polyaniline (PAni) gain much attention and cannot be replaced by any other magnetic material because they are less expensive, stable and widely used in high-frequency applications. Ferrites, belonging to ferromagnetic material which cannot be easily replaced by any other material as they are economic for a wide range of applications and ease of fabrication into complex shapes. Thus the use of hybrid fillers based on various combinations will be a possible solution for improved shielding effectiveness as well as the mechanical properties of nanocomposites.

Barium ferrite nanoparticles: a highly effective EMI shielding material

Electromagnetic interference (EMI) is one of the main causes for the failure of electronic devices working in close vicinity of EM field induced by the neighboring electronic device. Therefore, we report a facile synthesis of barium ferrite (BaFe12O19) nanoparticles via sol-gel technique for efficient EMI shielding application. These nanoparticles were annealed at 400 °C, 700 °C, and 850 °C to investigate the effect of temperature on shielding efficiency and morphology of BaFe12O19 nanoparticles. The structure, morphology, phase purity, magnetism, and shielding effectiveness were analyzed using Fourier-transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD), electron microscopy (SEM and TEM), vibrating sample magnetometer (VSM) and vector network analyzer, respectively. These studies suggest that BaFe12O19 nanoparticles annealed at 850 °C exhibit crystalline pure phase hexagonal structure with the high magnetic moment (31.32 emu g−1) and coercivity (2.7 kOe). The total shielding effectiveness of the same was found to be −17.57 dB at 11.58 GHz, which is much higher than those of earlier reported studies.

Lightweight and flexible Ni-Co alloy nanoparticle-coated electrospun polymer nanofiber hybrid membranes for high-performance electromagnetic interference shielding

Low-density, flexible and high-performance electromagnetic interference (EMI) shielding materials are urgently required to address the increasingly serious problem of radiation pollution. Ni-Co alloys with intrinsic conductivity and magnetism are good candidates for providing excellent EMI shielding performance. However, their high density and poor flexibility severely restrict their further applications in some specific fields. Herein, lightweight and flexible Ni-Co alloy nanoparticle-coated PAN-PU (P@Ni-Co) nanofiber membrane is fabricated through the combination of the electrospinning technique and the electroless deposition process, and it is employed as an effective EMI shielding material. Due to its remarkable conductivity of 1139.6 S/cm and the satisfactory saturation magnetization value of 49.6 emu/g, P@Ni-Co hybrid membrane with a thickness of 0.180 mm and a density of 0.59 g cm−3 exhibits excellent electromagnetic interference shielding effectiveness (EMI SE) of >68 dB over a wide frequency band (8–26.5 GHz); moreover, the average EMI SE reached as high as 77.8 dB with an absolute EMI shielding effectiveness (SSET) of 7325.8 dB cm2·g−1, which are higher than those for most of the reported EMI shielding materials. Compared to reflection, absorption makes a much larger contribution to the total EMI shielding effectiveness. These results suggest that Ni-Co alloy nanoparticle-coated PAN-PU nanofiber membrane would be very promising for applications as a thinner and lighter EMI shielding material.

Cyanate Ester Resin Filled with Graphene Nanosheets and NiFe2O4–Reduced Graphene Oxide Nanohybrids for Efficient Electromagnetic Interference Shielding

An effective electromagnetic interference (EMI) shielding cyanate ester (CE) composite has been fabricated with a combination of graphene nanosheets (GNSs) and nickel ferrite (NiFe2O[Formula: see text] particles. NiFe2O4 particles were loaded on the reduced graphene oxide (RGO) to improve the dispersibility while the composites were synthesized via solution blending method. Scanning electron micrographs (SEM) showed good dispersion of GNSs and RGO–NiFe2O4 in CE. Electromagnetic properties and EMI shielding effectiveness (SE) of the nanocomposites were determined over X-bands (8.2–12.4[Formula: see text]GHz). It was observed that the EMI shielding performance of composites was improved by increasing the filler loading of composites and absorption was found to be the dominant shielding mechanism. The total EMI SE is almost reaching 50[Formula: see text]dB for samples with thicknesses of [Formula: see text]2.7[Formula: see text]mm, which suggests that the GNSs/RGO–NiFe2O4/CE could be good candidates for highly efficient EMI shielding materials in the whole X-band.

High performance electromagnetic interference shielding of lamellar MoSi2/glass composite coatings by plasma spraying

MoSi2/glass composite coatings with different MoSi2 content were fabricated by low power plasma spraying. The microstructure, electrical conductivity, dielectric properties and electromagnetic interference (EMI) shielding effectiveness (SE) of MoSi2/glass composite coatings were investigated in this study. The EMI SE is found to be related with the electrical conductivity and dielectric property, which are attributed to the high aspect ratio of lamellar structure and well dispersion state of MoSi2. The average value of EMI SE is 24.2 dB in the frequency range of 8.2–12.4 GHz for the MoSi2/glass composite coating with 30wt% MoSi2 in 1.5 mm. The results indicate that the plasma sprayed MoSi2/glass composite coatings can be applied to effective EMI shielding materials.

Effect of Multiwalled Carbon Nanotubes on the Electromagnetic Interference Shielding Properties of Polyimide/Carbonyl Iron Composites

Electromagnetic interference (EMI) shielding materials with polyimide resin as matrix and hybrid fillers (carbonyl iron and multiwalled carbon nanotubes (MWCNTs)) as fillers were prepared, and their electromagnetic and EMI properties were investigated in the frequency range of 8.2–12.4 GHz. The microstructures of the composites show a uniform dispersion of the hybrid fillers. The effective complex permittivity and the EMI effectiveness of the composites increased with increase in the MWCNTs content. When the content of MWCNTs was 4 wt %, the effective complex permittivity and EMI effectiveness could reach 66.5 + 45.5 and 24 dB. The average values of the surface reflection (SER) and the internal absorption (SEA) increased 0.7 and 2.1 dB for 4 wt % MWCNTs composites, respectively, after the composites were heat treatment at 300 °C. Those results indicated that the polyimide matrix composites could be used as effective EMI shielding materials.

EMI Shielding Effectiveness of Polyvinyl Chloride and Carbon Fiber Composites in Building Construction

Electromagnetic Interference (EMI) shielding materials commonly refers to how effective the material in limiting the passage of electromagnetic radiation into the devices. This undesired interference may cause disturbances to the performance of the any electrical systems. Thus, with effective EMI shielding materials, electromagnetic radiations are blocked with barriers made of conductive materials. In military field, the operation of certain communication equipments such as radar system can be interfered by disturbances due to the electromagnetic radiation emitted by external sources. This paper presents the investigations on non-metal materials which are Polyvinyl Chloride (PVC) and carbon fiber composite as EMI shielding materials in building construction. These shielding materials are placed in the concrete block which casted based on the standard wall building of grade 30. These customized structures are proven to reduce signal penetration significantly in the high frequency range up to 2.4 GHz.

Dielectric property and electromagnetic interference shielding effectiveness of ethylene vinyl acetate‐based conductive composites: Effect of different type of carbon fillers

AbstractCarbon black, short carbon fiber (SCF), and multiwall carbon nano‐tube (MWNT)‐filled conductive composites were prepared from ethylene vinyl acetate copolymer. The dielectric property and electromagnetic interference (EMI) shielding of carbon black, MWNT, and SCF‐filled composites were studied with different filler loadings. The dielectric constant and loss of filled polymer composites is due to the formation of interfacial polarization in the polymer matrix. It was found that the dielectric constant, dielectric loss, and EMI shielding of filled composites depends on amount and type of filler loading. The results of different experiments have been discussed in the light of break down and formation of continuous conductive network in polymer matrix. The results indicate that these composites can be used as effective EMI shielding materials. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers.

Ti 3 SiC 2 material: An application for electromagnetic interference shielding

Ti 3 SiC 2 was prepared by hot-pressing sintering. The dielectric permittivity and electromagnetic interference (EMI) shielding effectiveness (SE) are measured for the Ti3SiC2 material and pure titanium (Ti) metal in the frequency range of 8.2–18 GHz (X-band and Ku-band). The results show that Ti3SiC2 material exhibits high complex permittivities at the measured frequencies. Compared to the EMI-SE achieved by pure Ti metal, an EMI-SE value as high as 35–54 dB has been achieved in the X-band and Ku-band frequencies for Ti3SiC2 material, which suggests that it should be an effective EMI shielding material for structural applications.