Electromagnetic Shielding by MXene-Graphene-PVDF Composite with Hydrophobic, Lightweight and Flexible Graphene Coated Fabric

State-of-the-art in carbides/carbon composites for electromagnetic wave absorption

Electromagnetic wave absorbing materials (EWAMs) have made great progress in the past decades, and are playing an increasingly important role in radiation prevention and antiradar detection due to their essential attenuation toward incident EM wave. With the flourish of nanotechnology, the design of high-performance EWAMs is not just dependent on the intrinsic characteristics of single-component medium, but pays more attention to the synergistic effects from different components to generate rich loss mechanisms. Among various candidates, carbides and carbon materials are usually labeled with the features of chemical stability, low density, tunable dielectric property, and diversified morphology/microstructure, and thus the combination of carbides and carbon materials will be a promising way to acquire new EWAMs with good practical application prospects. In this review, we introduce EM loss mechanisms related to dielectric composites, and then highlight the state-of-the-art progress in carbides/carbon composites as high-performance EWAMs, including silicon carbide/carbon, MXene/carbon, molybdenum carbide/carbon, as well as some uncommon carbides/carbon composites and multicomponent composites. The critical information regarding composition optimization, structural engineering, performance reinforcement, and structure-function relationship are discussed in detail. In addition, some challenges and perspectives for the development of carbides/carbon composites are also proposed after comparing the performance of some representative composites.

The Rise of MXene: A Wonder 2D Material, from Its Synthesis and Properties to Its Versatile Applications-A Comprehensive Review

MXene, a new member of 2D material, unites the eminence of hydrophilicity, large surface groups, superb flexibility and excellent conductivity. Because of its prodigious characteristics, MXene has gained much approbation among researchers worldwide. MXene's noteworthy features, such as its electrical conductivity, structural property, magnetic behaviour, etc., manifest a broad spectrum of applications, including environment, catalytic, wireless communications, electromagnetic interference (EMI) shielding, drug delivery, wound dressing, bio-imaging, antimicrobial and biosensor. In this review article, an overview of the latest advancements in the applications of MXene has been reported. First, various synthesis strategies of MXene will be summarized, followed by the different structural, physical and chemical properties. The current advances in versatile applications have been discussed. The article aims to incorporate all the possible applications of MXene, making it a versatile material that juxtaposes it with other 2D materials. A separate section is dedicated to the bottlenecks for future developments and recommendations.

Graphene-Based Electrospun Fibrous Materials with Enhanced EMI Shielding: Recent Developments and Future Perspectives

As a result of advancements in electronics/telecommunications, electromagnetic interference (EMI) pollution has gotten worse. Hence, fabrication/investigation of EMI shields having outstanding EMI shielding performance is necessary. Electrospinning (ES) has recently been established in several niches where 1D nanofibers (NFs) fabricated by ES can provide the shielding of EM waves, owing to their exceptional benefits. This review presents the basic correlations of ES technology and EMI shielding. Diverse graphene (GP)-based fibrous materials directly spun via ES as EMI shields are discussed. Electrospun EMI shields as composites through diverse post-treatments are reviewed, and then different factors influencing their EMI shielding characteristics are critically summarized. Finally, deductions and forthcoming outlooks are given. This review provides up to date knowledge on the advancement of the application of graphene-based electrospun fibers/composite materials as EMI shields and the outlook for high-performance electrospun fibers/composite-based EMI shielding materials.

N-Doped Honeycomb-like Ag@N-Ti3C2Tx Foam for Electromagnetic Interference Shielding

To solve the pollution problem of electromagnetic waves, new electromagnetic shielding materials should meet the requirements of being lightweight with high electrical conductivity. In this work, the combination of silver (Ag) nanoparticles and nitrogen doping (N-doping) was expected to tune the electromagnetic and physical properties of Ti₃C₂T_x MXene, and the Ag@N-Ti₃C₂T_x composites were fabricated through the hydrothermal reactions. The nitrogen doped (N-doped) Ag@Ti₃C₂T_x composites showed a hollow structure with a pore size of 5 μm. The influence of N-doped degrees on the electromagnetic interference (EMI) shielding performance was investigated over 8-18 GHz. Therefore, the controlled N-doping composites exhibited reflection-based EMI shielding performance due to the electrical conductivity and the special three-dimensional (3D) honeycomb-like structure. The achieved average EMI shielding values were 52.38 dB at the X-band and 72.72 dB at the K_u-band. Overall, the Ag@N-Ti₃C₂T_x foam, due to its special 3D honeycomb-like structure, not only meets the characteristics of light weight, but also exhibits ultra-high-efficiency EMI shielding performance, revealing great prospects in the application of electromagnetic wave shielding field.

MXene-Graphene Composites: A Perspective on Biomedical Potentials

MXenes, transition metal carbides and nitrides with graphene-like structures, have received considerable attention since their first discovery. On the other hand, Graphene has been extensively used in biomedical and medicinal applications. MXene and graphene, both as promising candidates of two-dimensional materials, have shown to possess high potential in future biomedical applications due to their unique physicochemical properties such as superior electrical conductivity, high biocompatibility, large surface area, optical and magnetic features, and extraordinary thermal and mechanical properties. These special structural, functional, and biological characteristics suggest that the hybrid/composite structure of MXene and graphene would be able to meet many unmet needs in different fields; particularly in medicine and biomedical engineering, where high-performance mechanical, electrical, thermal, magnetic, and optical requirements are necessary. However, the hybridization and surface functionalization should be further explored to obtain biocompatible composites/platforms with unique physicochemical properties, high stability, and multifunctionality. In addition, toxicological and long-term biosafety assessments and clinical translation evaluations should be given high priority in research. Although very limited studies have revealed the excellent potentials of MXene/graphene in biomedicine, the next steps should be toward the extensive research and detailed analysis in optimizing the properties and improving their functionality with a clinical and industrial outlook. Herein, different synthesis/fabrication methods and performances of MXene/graphene composites are discussed for potential biomedical applications. The potential toxicological effects of these composites on human cells and tissues are also covered, and future perspectives toward more successful translational applications are presented. The current state-of-the-art biotechnological advances in the use of MXene-Graphene composites, as well as their developmental challenges and future prospects are also deliberated. Due to the superior properties and multifunctionality of MXene-graphene composites, these hybrid structures can open up considerable new horizons in future of healthcare and medicine.

Improving the EMI shielding of graphene oxide (GNO)-coated glass-fiber-GNO-MA-grafted polypropylene (PP) composites and nylon 1D-2D nanocomposite foams

The proliferation of the latest electronic gadgets and wireless communication devices can trigger electromagnetic interference (EMI), which has a detrimental impact on electronic devices and humans. Efficient EMI shielding materials are required for EMI-SE and they should be durable in external environments, lightweight, and cost-effective. GNO-coated glass-fiber–GNO–maleic anhydride-grafted polypropylene (MAPP) composite and carbon fiber-reinforced nylon 1D–2D nanocomposite foam were successfully prepared via a cost-effective thermal process. The composites were characterized using scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The PP and nylon-based composites with ∼13% filler showed maximum electrical conductivity (EC) of 878 mS cm⁻¹ and 1381 mS cm⁻¹, respectively. The GNO-coated glass-fiber–GNO–MAPP foam displays a maximum EMI-SE of 120.6 dB, while the nylon graphene–carbon nanotube–metal nanoplatelet foam exhibits a maximum EMI-SE of 139.1 dB in the X-band region. The GFCFFeGMAPP composite possesses a minimum thickness of 2.56 mm and blocks most incoming radiation. These are some of the highest EMI-SE values reported so far for glass fiber and nylon-based composites, and the nylon-based composite showed excellent properties compared to the glass fiber-based composite. Thus, we believe that the developed composites can be used in a wide range of real applications, such as in military vehicles, aviation, automobiles, and the packaging of electronic circuits.

The proliferation of the latest electronic gadgets and wireless communication devices can trigger electromagnetic interference (EMI), which has a detrimental impact on electronic devices and humans.

Electromagnetic Interference Shielding with 2D Copper Sulfide

Electronic devices in highly integrated and miniaturized systems demand electromagnetic interference shielding within nanoscale dimensions. Although several ultrathin materials have been proposed, satisfying various requirements such as ultrathin thickness, optical transparency, flexibility, and proper shielding efficiency remains a challenge. Herein, we report an ultrahigh electromagnetic interference (EMI) SSE/t value (>10⁶ dB cm²/g) using a conductive CuS nanosheet with thickness less than 20 nm, which was synthesized at room temperature. We found that the EMI shielding efficiency (EMI SE) of the CuS nanosheet exceeds that of the traditional Cu film in the nanoscale thickness, which is due to high conductivity and the presence of internal dipole structures of the CuS nanosheet that contribute to absorption due to the damping of dipole oscillation. In addition, the CuS nanosheet exhibited high mechanical stability (10⁴ cycles at 3 mm bending radius) and air stability (25 °C, 1 atm), which far exceeded the performance of the Cu nanosheet film. This remarkable performance of nanometer-thick CuS proposes an important pathway toward designing EMI shielding materials for wearable, flexible, and next-generation electronic applications.

MXenes based nano-heterojunctions and composites for advanced photocatalytic environmental detoxification and energy conversion: A review

Extensive research is being done to develop multifunctional advanced new materials for high performance photocatalytic applications in the field of energy production and environmental detoxification, MXenes have emerged as promising materials for enhancing photocatalytic performance owing to their excellent mechanical properties, appropriate Fermi levels, and adjustability of chemical composition. Numerous experimental and theoretical research works implied that the dimensions of MXenes have a significant impact on their performance. For photocatalysis to thrive in the future, we must understand the current state of the art for MXene in different dimensions. Using MXene co-catalysts in widely used in photocatalytic applications such as CO₂ reduction, hydrogen production and organic pollutant oxidation, this study focuses on the most recent developments in MXenes based materials, structural modifications, innovations in reaction and material engineering. It has been reported that using 5 mg of CdS-MoS₂-MXene researchers were able to generate as high as 9679 μmol/g/h hydrogen under visible light. The MXenes based heterojunction photocatalyst Co₃O₄/MXene was utilized to degrade 95% bisphenol A micro-pollutant in just 7 min. Numerous novel materials, their preparations and performances have been discussed. Depending upon the nature of MXene-based materials, the synthesis techniques and photocatalytic mechanism of MXenes as co-catalyst are also summarized. Finally, some final thoughts and prospects for developing highly efficient MXene-based photocatalysts are provided which will indeed motivate researchers to design novel hybrid materials based on MXenes for sustainable solutions to energy and pollution issues.

Hydrothermal-Assisted Synthesis and Stability of Multifunctional MXene Nanobipyramids: Structural, Chemical, and Optical Evolution

Recent advancements in two-dimensional materials have brought MXene (Ti₃C₂) into attention due to its exciting properties as a very promising material for various applications. In this work, we report a novel Ti₃C₂ nanobipyramid (Ti₃C₂ NB) structure obtained through a three-step process involving exfoliation, delamination, and subsequent hydrothermal treatment. The morphological and textural properties at each step of synthesis were studied using an array of experimental techniques such as transmission electron microscopy, scanning electron microscopy, and atomic force microscopy and the chemical properties through X-ray diffraction, Raman, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis. The Ti₃C₂ NBs exhibit fluorescence with an excitation-dependent emission. Further, the effect of temperature and pH on the fluorescence was also investigated, which opens up its scope in bioanalytical applications. Ti₃C₂ NBs showed a ∼43% increase in photoluminescence intensity from pH 3 to 11 while a ∼38% increase with the temperature from 20 to 80 °C. Usually, MXenes are highly susceptible to oxidation, but the Ti₃C₂ NBs were found to be chemically and optically stable even after 30 days. Bestowed with good hydrophilicity, the material exhibited high biocompatibility on the mouse fibroblast cell line L929. Further, L929 cells also showed good cellular adhesion on a Ti₃C₂ NB-modified glass substrate. These properties pave a way for its multifunctional ability as a sensor for pH and temperature as well as bioimaging.

Progress in polymers and polymer composites used as efficient materials for EMI shielding

The explosive progress of electronic devices and communication systems results in the production of undesirable electromagnetic pollution, known as electromagnetic interference. The accumulation of electromagnetic radiation in space results in the malfunction of commercial and military electronic appliances, and it may have a negative impact on human health. Thus, the shielding of undesirable electromagnetic interference has become a serious concern of the modern society, and has been a very perspective field of research and development. This paper provides detailed insight into current trends in the advancement of various polymer-based materials with the effects of electromagnetic interference shielding. First, the theoretical aspects of shielding are outlined. Then, the comprehensive description of the structure, morphology and functionalization of the intrinsic conductive polymers, polymers filled with the different types of inorganic and organic fillers, as well as multifunctional polymer architectures are provided with respect to their conductive, dielectric, magnetic and shielding characteristics.

Exfoliation and Defect Control of Two-Dimensional Few-Layer MXene Ti3C2Tx for Electromagnetic Interference Shielding Coatings

Defect-controlled exfoliation of few-layer transition-metal carbide (f-Ti₃C₂T_x) MXene was demonstrated by optimizing chemical etching conditions, and electromagnetic interference (EMI) shielding coatings were explored. The structural features such as layer morphology, lateral size, layer thickness, defect density, and mechanical stability of the exfoliated f-Ti₃C₂T_x were strongly dependent on exfoliation conditions. By selecting appropriate exfoliation conditions, moderate etching time leads to the formation of quality f-Ti₃C₂T_x with lesser defects, whereas longer etching time can break the layer structure and increase defect density, structural misalignment, and oxidative products of f-Ti₃C₂T_x. The resultant fabricated free-standing flexible f-Ti₃C₂T_x films exhibited electrical conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) in the X-band of about 3669 ± 33 S/m and 31.97 dB, respectively, at a thickness of 6 μm. The large discrepancy in EMI SE performance between quality (31.97 dB) and defected (3.164 dB) f-Ti₃C₂T_x sheets is attributed to interconnections between f-Ti₃C₂T_x nanolaminates interrupted by defects and oxidative products, influencing EMI attenuation ability. Furthermore, the demonstrated solution-processable high-quality f-Ti₃C₂T_x inks are compatible and, when applied for EM barrier coating on various substrates, including paper, cellulose fabric, and PTFE membranes, exhibited significant EMI shielding performance. Moreover, controlling defects in f-Ti₃C₂T_x and assembly of heterogeneous disordered carbon-loaded TiO₂-Ti₃C₂T_x ternary hybrid nanostructures from f-Ti₃C₂T_x by tuning etching conditions could play an enormous role in energy and environmental applications.

EMI Shielding of the Hydrophobic, Flexible, Lightweight Carbonless Nano-Plate Composites

The cost-effective spray coated composite was successfully synthesis and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction techniques. The one step synthetic strategy was used for the synthesis of nanoplates that have a crystalline nature. The composites are amorphous and hydrophobic with micron thickness (<400 m). The maximum contact angle showed by composite is 132.65° and have wetting energy of -49.32 mN m-1, spreading coefficient -122.12 mN m-1, and work of adhesion 23.48 mN m-1. The minimum thickness of synthesized nanoplate is 3 nm while the maximum sheet resistance, resistivity, and electrical conductivity of the composites are 11.890 ohm sq-1, 0.4399 Ω.cm-1, and 8.967 S.cm-1, respectively. The cobalt nanoplate coated non-woven carbon fabric (CoFC) possesses excellent sheet resistance, hydrophobic nature, and EMI shielding efficiency of 99.99964%. The composite can block above 99.9913% of incident radiation (X band). Hence, the composite can be utilized in application areas such as medical clothes, mobile phones, automobiles, aerospace, and military equipment.

High electromagnetic interference shielding of poly(ether-sulfone)/multi-walled carbon nanotube nanocomposites fabricated by an eco-friendly route

High-performance polymer matrix nanocomposites based on poly(ether-sulfone) (PES) matrix reinforced with multi-walled carbon nanotubes (MWCNTs) were fabricated using planetary ball mill followed by hot pressing. Their electrical properties and the electromagnetic interference shielding effectiveness (EMI-SE) were investigated and discussed. A percolation threshold of about 0.65 vol% MWCNT was obtained. The electrical conductivity was increased by more than ten orders of magnitude at the percolation threshold and to approximately 0.01 S cm^-1 at 6.67 vol% (or 10 wt%) MWCNT. This is a significant improvement. The highest EMI-SE of about 29-30 dB (both in the X-band and K_u-band) was obtained for the 6.67 vol% MWCNT filled nanocomposites with a thickness of 0.9 mm. The specific EMI-SE of these nanocomposites were found to be higher than the literature values. The thermal stability and the char yield (measured at 900 °C) of the nanocomposites were found to be more than 470 °C and 40.6%, respectively.

Mechanotribological Aspects of MXene-Reinforced Nanocomposites

MXenes are recently discovered 2D nanomaterial with superior mechanical, thermal, and tribological properties, being commonly employed in a wide variety of critical research areas, ranging from cancer therapy to energy and environmental applications. Due to their special properties, such as mechanoceramic nature with excellent mechanical performance, thermal stability and rich surface properties, MXenes have tremendous potential as advanced composite structures, especially those based on polymers due to a great affinity between macromolecules and the terminating groups of 2D MXenes. MXenes have been extensively explored in metal matrix nanocomposites as well as in solid- or liquid-based lubrication systems owing to the 2D structure and antifriction characteristics. The purpose of the this paper is to provide a comprehensive insight into the material, mechanical, and tribological properties of the MXene nanolayers with discussions on the recent advancements attained from MXene-reinforced nanocomposites starting with the synthesis, fabrication techniques, intricacies of the underlying physics and mechanisms, and finally focusing on the progress in computational studies. This analysis of MXene-based composites will stimulate an emerging field with innumerable opportunities and ample potentials to produce newfangled materials and structures with targeted properties.

Elastomer nanocomposites containing MXene for mechanical robustness and electrical and thermal conductivity

A novel 2D nanomaterial, Ti₃C₂T_x MXene, added conductivity and reinforcement to a common elastomer, nitrile butadiene rubber (NBR). X-ray diffraction revealed the intercalation of lithium ions and elastomer chains into the MXene interlayer spacing, which enabled exfoliation in the elastomer. The reaction between MXene and NBR was proved by a stepwise Fourier transform infrared spectroscopy. With increase in MXene fractions, electrical and thermal conductivity of the composite increased to 9 × 10^-5 S cm^-1 and 0.69 W m^-1 K^-1, respectively. At only 2.8 vol% MXene, a swelling ratio of 1.61 was achieved, representing a 75% reduction compared to NBR containing either graphene or carbon nanotubes at the same filler fraction. Tensile tests showed that with the increase in MXene content, Young's modulus increased while both tensile strength and elongation at break first increased and then decreased. Overall, latex compounding proved to be an efficient technique for forming NBR/MXene nanocomposites. The revealed reaction between MXene and NBR to create functional polymer nanocomposites could provide a platform for utilising MXene for other polymers.

Flexible, Robust, and Multifunctional Electromagnetic Interference Shielding Film with Alternating Cellulose Nanofiber and MXene Layers

Flexible, lightweight, robust, and multifunctional characteristics are greatly desirable for next-generation wearable electromagnetic interference (EMI) shielding materials. In this work, an alternating multilayered structure with robust polymer frame layers and directly contacted conducting layers was designed to prepare high-performance EMI films. Especially, the multilayered films containing alternating cellulose nanofiber (CNF) layers and MXene layers are fabricated via a facile and efficient alternating vacuum filtration approach. Deriving from the mechanical frame effect acted by CNF layers in, which is capable of preventing the nanosized "zigzag" crack in MXene layers from growing to the whole film, the alternating multilayered film (CNF@MXene) revealed the improved mechanical strength (112.5 MPa) and toughness (2.7 MJ m^-3) compared to both freestanding MXene film and homogeneous CNF/MXene film. Meanwhile, the directly contacted MXene layers resulted in the increased electrical conductivity from 2 (homogeneous CNF/MXene film) to 621-82 S m^-1 (CNF@MXene films). In conjunction with the extra "reflection-absorption-zigzag reflection" mechanism among the alternating multilayers, CNF@MXene films demonstrated an exceptional EMI shielding effectiveness of ∼40 dB in the X-band and K-band and high specific shielding effectiveness up to 7029 dB cm² g^-1 at a thickness of only 0.035 mm. Besides, the excellent mechanical flexibility ensured the stable EMI shielding and electrical properties, which can withstand the folding test more than 1000 times without obvious reduction. Moreover, the excellent electrical conductivity endows the alternating multilayered film with an outstanding and steady Joule heating performance, which could reach more than 100 °C at only 6 V impressed voltage to within 10 s. As a result, our alternating multilayered film with reinforced EMI shielding and Joule heating performance is promising in the next-generation intelligent protection devices applying in cold and complex practical environments.

An effective utilization of MXene and its effect on electromagnetic interference shielding: flexible, free-standing and thermally conductive composite from MXene–PAT–poly(p-aminophenol)–polyaniline co-polymer

MXene and conductive polymers are attractive candidates for electromagnetic interference shielding (EMI) applications. The MXene–PAT-conductive polymer (CP) composites were fabricated by a cost-effective spray coating technique and characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. A new approach has been developed for the synthesis of exfoliated MXene. The MXene–PAT–poly(p-aminophenol)–polyaniline co-polymer composite exhibited good electric conductivity (EC) of 7.813 S cm⁻¹. The composites revealed an excellent thermal properties, which were 0.687 W (m K)⁻¹ thermal conductivity, 2.247 J (g K)⁻¹ heat capacity, 0.282 mm² s⁻¹ thermal diffusivity and 1.330 W s^1/2 m⁻² K⁻¹ thermal effusivity. The composites showed 99.99% shielding efficiency and the MXene–PAT–PANI–PpAP composite (MXPATPA) had EMI shielding effectiveness of 45.18 dB at 8.2 GHz. The reduced form of MXene (r-Ti₃C₂T_x) increased the shielding effectiveness (SE) by 7.26% and the absorption (SE_A) was greatly enhanced by the ant farm like structure. The composites possess excellent thermal and EMI SE characteristics, thus can be applied in areas, such as mobile phones, military utensils, heat-emitting electronic devices, automobiles and radars.

MXene and conductive polymers are attractive candidates for electromagnetic interference shielding (EMI) applications.

Fabrication of Flexible, Lightweight, Magnetic Mushroom Gills and Coral-Like MXene⁻Carbon Nanotube Nanocomposites for EMI Shielding Application

MXenes, carbon nanotubes, and nanoparticles are attractive candidates for electromagnetic interference (EMI) shielding. The composites were prepared through a filtration technique and spray coating process. The functionalization of non-woven carbon fabric is an attractive strategy. The prepared composite was characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and Raman spectroscopy. The MXene-oxidized carbon nanotube-sodium dodecyl sulfate composite (MXCS) exhibited 50.5 dB (99.999%), and the whole nanoparticle-based composite blocked 99.99% of the electromagnetic radiation. The functionalization increased the shielding by 15.4%. The composite possessed good thermal stability, and the maximum electric conductivity achieved was 12.5 Scm-1. Thus, the composite shows excellent potential applications towards the areas such as aeronautics, mobile phones, radars, and military.

Carbon Fibers Encapsulated with Nano-Copper: A Core‒Shell Structured Composite for Antibacterial and Electromagnetic Interference Shielding Applications

A facile and scalable two-step method (including pyrolysis and magnetron sputtering) is created to prepare a core–shell structured composite consisting of cotton-derived carbon fibers (CDCFs) and nano-copper. Excellent hydrophobicity (water contact angle = 144°) and outstanding antibacterial activity against Escherichia coli and Staphylococcus aureus (antibacterial ratios of >92%) are achieved for the composite owing to the composition transformation from cellulose to carbon and nano-size effects as well as strong oxidizing ability of oxygen reactive radicals from interactions of nano-Cu with sulfhydryl groups of enzymes. Moreover, the core–shell material with high electrical conductivity induces the interfacial polarization loss and conduction loss, contributing to a high electromagnetic interference (EMI) shielding effectiveness of 29.3 dB. Consequently, this flexible and multi-purpose hybrid of nano-copper/CDCFs may be useful for numerous applications like self-cleaning wall cladding, EMI shielding layer and antibacterial products.

Electrical Properties and Electromagnetic Interference Shielding Effectiveness of Interlayered Systems Composed by Carbon Nanotube Filled Carbon Nanofiber Mats and Polymer Composites

The demand for multifunctional requirements in aerospace, military, automobile, sports, and energy applications has encouraged the investigation of new composite materials. This study focuses on the development of multiwall carbon nanotube (MWCNT) filled polypropylene composites and carbon nanofiber composite mats. The developed systems were then used to prepare interlayered composites that exhibited improved electrical conductivity and electromagnetic interference (EMI) shielding efficiency. MWCNT-carbon nanofiber composite mats were developed by centrifugally spinning mixtures of MWCNT suspended in aqueous poly(vinyl alcohol) solutions. The developed nanofibers were then dehydrated under sulfuric acid vapors and then heat treated. Interlayered samples were fabricated using a nanoreinforced polypropylene composite as a matrix and then filled with carbon fiber composite mats. The in-plane and through-plane electrical conductivity of an eight-layered flexible carbon composite (0.65 mm thick) were shown to be 6.1 and 3.0 × 10⁻² S·cm⁻¹, respectively. The EMI shielding effectiveness at 900 MHz increased from 17 dB for the one-layered composite to 52 dB for the eight-layered composite. It was found that the reflection of the electromagnetic waves was the dominating mechanism for EMI shielding in the developed materials. This study opens up new opportunities for the fabrication of novel lightweight materials that are to be used in communication systems.

Multifunctional, Polyurethane-Based Foam Composites Reinforced by a Fabric Structure: Preparation, Mechanical, Acoustic, and EMI Shielding Properties

This study proposes multifunctional, fabric-reinforced composites (MFRCs) based on a bionic design, which are prepared by two-step foaming and a combination of different fabric constructs. MFRCs are evaluated in terms of sound absorption, compression resistance, electromagnetic interference shielding effectiveness (EMI SE), and drop impact, thereby examining the effects of fabric structures. The test results indicate that the enhanced composites have superiority functions when combined with carbon fabric in the upper layer and spacer fabric in the lower layer. They have maximum compression resistance, which is 116.9 kPa at a strain of 60%, and their compression strength is increased by 135.9% compared with the control specimen. As a result of the fabric structure on the cell morphology, the maximum resonance peak shifts toward high frequency when using spacer fabric as the intermediate layer. The average sound absorption coefficient is above 0.7 at 1000–4000 Hz. The reinforced composites possessed EMI SE of 50 dB at 2 GHz; an attenuation rate of 99.999% was obtained, suggesting a good practical application value. Furthermore, the cushioning effect of the MFRCs improved significantly, and the maximum dynamic contact force during the impact process was reduced by 57.28% compared with composites without any fabric structure. The resulting MFRCs are expected to be used as sound absorbent security walls, machinery equipment, and packaging for commercial EMI shielding applications in the future.