Absorption-dominated Electromagnetic Interference Shielding Research Articles

Ultralight, Conductive Ti3C2Tx MXene/PEDOT:PSS Hybrid Aerogels for Electromagnetic Interference Shielding Dominated by the Absorption Mechanism.

MXene aerogels with a porous microstructure are a promising electromagnetic interference (EMI) shielding material due to its low density and excellent electrical conductivity, which has attracted widespread attention. Compared with traditional EMI shielding materials that rely on reflection as the primary mechanism, MXene aerogels with absorption as the dominant mechanism have greater potential for development as a novel EMI shielding material because of its ability to reduce environmental contamination from reflected electromagnetic (EM) waves from materials. In this study, a novel Ti3C2Tx MXene/PEDOT:PSS hybrid aerogel was presented by freeze-drying and thermal annealing using few-layered Ti3C2Tx MXene and the conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). PEDOT:PSS not only improved the gelling ability of Ti3C2Tx but also successfully established a conductive bridge between MXene nanosheets. The experimental results demonstrated that the hybrid aerogel exhibited an obvious porous microstructure, which was beneficial for the multiple scattering of EM waves within the materials. The EMI shielding effectiveness and specific shielding effectiveness reached up to 59 dB and 10,841 dB·cm2·g-1, respectively, while the SER/SET ratio value was only 0.05, indicating superior wave absorption performance. Furthermore, the good impedance matching, due to the electrical conductance loss and polarization loss effect of the composites, plays a critical role in their excellent wave absorption and EMI shielding performance. Therefore, this work provides a practical approach for designing and fabricating lightweight absorption-dominated EMI shielding materials.

Heterolayered Composite of Carbon Nanofibers Sandwiched between Poly(ethylene terephthalate) and Polyurethane for Flexible Electromagnetic Shielding Application

Multifunctional flexible films having properties of low filler dosing, light weight, small thickness, excellent environmental stability, and durability are highly demanded for absorption dominant electromagnetic interference (EMI) shielding in wearable electronic gadgets and in electronic packaging for civil, military, and space applications. For this, layered flexible films (FFs) of poly(ethylene terephthalate) (PET), carbon nanofibers (CNFs), and polyurethane (PU) were fabricated. The sheet resistance decreased from 48.9 × 103 to 8.3 × 102 Ω/cm2 on increasing the CNF wt %, which resembled an improved 3D CNF network. This 3D CNF network was developed to achieve a total shielding efficiency (SET) of ∼25 dB (>99.9%) at 2 wt % for just 0.5 mm thickness of the film. Importantly, the fabricated film showed exceedingly consistent EMI shielding performance in a complex environment, with 22.9 dB and 23.6 dB SET values even after 1 h of ultrasonication treatment in water and 10 000 mechanical bending cycles, respectively. Conveniently, owing to the increased interfacial polarization, conduction loss, and multiple reflections, these FFs exhibited efficient EMI shielding accommodating the absorption dominant mechanism. The EMI shielding was also numerically analyzed through CST microwave studio software over the broad frequency range of 1–18 GHz. This work contributes to the fabrication and study of layered flexible films to enhance mechanical properties and achieve high absorption dominant EMI shielding for future-generation portable/wearable gadgets and packaging applications.

Robust organic semiconductor thermoset composite films based on Crystallization-Driven Self-Assembled nanofibers of Poly(3-hexylthiophene) block copolymers

Crystallization-driven self-assembly (CDSA) has been widely used as a fascinating technique to prepare nanostructures, especially nanofibers containing conjugated polymers, while realizing its practical application remains challenging. For the wide application of semiconductor micelles, amphiphilic poly(3-hexylthiophene)-b-poly(ε-caprolactone) (P3HT-b-PCL) block copolymers were synthesized to obtain stable nanofiber dispersions via CDSA, and subsequently combined with epoxy resin systems to prepare composite films. The thermoset composite films containing 12.5 wt% nanofibrous P3HT exhibited satisfactory mechanical strength and flexibility. They were further doped in an acetonitrile solution of Cu(OTf)2 to obtain conductivity up to 1.94 S/m. Notably, the electromagnetic interference (EMI) shielding effectiveness (SE) of the composite films in the X-band was 23.8 dB at a thickness of 1.1 mm, which was the best value obtained so far for conjugated polymers in thermoset systems, even better than that of epoxy composites containing carbon nanofillers. Due to the proper conductivity and interconnected nanofiber conductive network, this composite film showed a high absorption-dominated EMI shielding performance (absorption coefficient A = 0.71). This work demonstrates a promising strategy to prepare organic semiconductor composite films, which is expected to be applied to the preparation of absorption-dominated electromagnetic shielding films and high-performance thermoelectric devices.

Investigation on the structural quality dependent electromagnetic interference shielding performance of few-layer and lamellar Nb2CTx MXene nanostructures

Tunable Electromagnetic Interference (EMI) shielding behaviors of 2D MXene (Nb2CTx) were explored via different exfoliation conditions. Stacked, lamellar few-layer, oxygen-related surface functional groups, and structural defects along with oxidative products of Nb2CTx were identified by tuning chemical etching conditions during one-step exfoliation process. Exfoliation of Nb2CTx with a tightly packed stacked structure remarked at lower etching times. The unpacking of Nb2CTx into lamellar morphology followed by separated few-layer Nb2CTx remarked at moderate etching time, whereas structural misalignment, defects, and oxidation of Nb2CTx occurred during prolonged chemical etching times. Synergistic effect of one-step extracted few-layers and lamellar structured Nb2CTx favorably enrich the assembly of multiple electrical conductive pathways responsible for absorption dominated EMI shielding performance in X- and Ku-band region. The assembled wax nanocomposites with 80% of Nb2CTx loading exfoliated at 100 h etching time at a thickness of 1 mm exhibited EMI shielding effectiveness of about 44.09 ± 1.99 dB at 12 GHz, and its EMI attenuation mechanism explained by conduction and eddy current loss. The combined action of few-layer and lamellar Nb2CTx nanostructures could be interesting for making novel shielding materials; open a new avenue for niobium series in the MXene family for elaborated applications.

Flexible 3D porous graphene film decorated with nickel nanoparticles for absorption-dominated electromagnetic interference shielding

Electromagnetic interference (EMI) shielding materials are vital for aerospace, military and portable wearable electronic equipment. Developing a high performance absorption-dominated EMI shielding materials with flexibility and lightness remains a challenge. Herein, we report an EMI shielding flexible thin-film composed of a 3D laser induced graphene (LIG) on polyimide substrate and magnetic nickel nanoparticles (Ni NPs) decorated in the porous LIG network. The 3D pore structure and interconnected conductive network ​​of LIG can cause the dielectric loss and multiple internal reflection dissipation of incident electromagnetic waves. Combined with the magnetic loss effect of Ni NPs, the composite thin-film exhibits ultra-efficient absorption-dominated EMI shielding performance. The EMI shielding effectiveness (SE) of a single layer optimized composite thin-film is 55 dB in the X-band (8.2–12.4 GHz) with absorption rate of 82%. The composite thin-film also possesses high flexibility with 89% EMI SE retention after 500 bendings. Furthermore, double layered composite film with thickness of only 0.327 mm can be easily prepared on both side of the polyimide substrate, exhibiting EMI SE as high as 79 dB with the absorption rate of 86%, which is superior than most of carbon- and Ni-based EMI shielding materials. Our findings may pave the way for designing high performance flexible absorption-dominated EMI shielding materials.

Role of graphitization-controlled conductivity in enhancing absorption dominated EMI shielding behavior of pyrolysis-derived Fe3C@C-PVDF nanocomposites

The role of improved graphitization-induced conductivity on imparting better electromagnetic interference (EMI) shielding effectiveness (SE) in the X-band frequency regime is demonstrated in pyrolysis-derived Fe3C@C based nanocomposites with PVDF polymer. Variation of synthesis temperature (Ts) is used as a strategic tool to modulate the graphitization and the associated conductivity of Fe3C@C particles. Two different carbonaceous-nanomaterials, both embedded with graphite encapsulated Fe3C-nanoparticles were synthesized at Ts = 800 °C (Fe-800) and Ts = 1000 °C (Fe-1000). We have shown that a higher synthesis temperature results in a thicker well-graphitized carbon-shell around the core (Fe3C) nanoparticles. The better degree of graphitization makes the samples better conducting. These two samples were dispersed separately in flexible polyvinylidene fluoride (PVDF) matrix to form polymer-nanocomposites. The SE of the PVDF:Fe-1000 nanocomposite film is higher than that of the PVDF:Fe-800 nanocomposite film. This high SE of the PVDF:Fe-1000 nanocomposite film is associated with the higher conductivity resulting from the higher degree of graphitization of the Fe-1000 sample. Effectively, the synergetic effects of electric and magnetic losses enhance the absorption-dominated EMI shielding of our nanocomposite-system, making them potential candidates for their direct industrial applications. Simultaneously, our work provides a strategy to control the EMI-SE of nanocomposites through control of the synthesis parameters.

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.

Reduced graphene oxide/Fe2O3 hollow microspheres coated sponges for flexible electromagnetic interference shielding composites

In this work, the low-density, compressible and porous composites are fabricated by simply coating polyurethane (PU) sponge with reduced graphene oxide (rGO) and hematite (Fe2O3) hollow microspheres for the application of absorption-dominant electromagnetic interference (EMI) shielding composites in X-band (8.2–12.4 GHz). By coating rGO on the skeleton of PU sponge, the composites possess high EMI shielding effectiveness of 37.45 dB. By further incorporating Fe2O3 hollow microspheres as the coating material along with rGO, the absorption of the electromagnetic waves enhances from 72.6% to 94.5% owing to the enhanced dielectric loss and better impedance matching at the air/shield interface. Moreover, the porous structure of the coated sponge facilitates absorption-dominant EMI shielding effectiveness owing to low density, conduction loss, multiple reflections and scattering of EM waves. In addition, the layered structure can further improve the absorption of the electromagnetic waves up to 97.3% by selectively stacking the rGO coated and rGO/Fe2O3 coated sponges, which serve as reflection and absorption layers, respectively.

Reduced graphene oxide/zinc oxide coated wearable electrically conductive cotton textile for high microwave absorption

Due to intensive development in smart electronics and energy devices, wearable electromagnetic interference (EMI) shielding materials such as conducting textiles have emerged to protect human as well as sensitive electronics from electromagnetic pollution. In this work, zinc oxide (ZnO) and reduced graphene oxide (rGO) coated wearable cotton fabrics have been prepared for the application of EMI shielding effectiveness in X-band (8.2–12.4 GHz). The uniform coating of ZnO nanoparticles is achieved by the easy and cost effective in-situ sol-gel method, whereas the uniform coating of rGO is achieved by simple spraying of graphene oxide solution followed by thermal reduction. It is observed that the total EMI shielding effectiveness increases with the rGO loading, however, the reflection loss decreases owing to improved conductivity of the cotton fabric. The as-prepared rGO/ZnO coated cotton (ZnO + 7 wt% rGO) achieves highest total EMI shielding effectiveness of ~99.999% (54.7 dB), which is shared by ~17.783% of reflection and ~82.216% of absorption. Such high absorption dominant EMI shielding is attributed to highly dielectric ZnO nanoparticles, highly conductive rGO sheets and the core-shell structure of the coated cotton fabric. It is also concluded that the excessive loading of rGO can block all the pores of the cotton fabric which is not beneficial for high absorption of the electromagnetic waves. The high absorption of ~90% is demonstrated when the ZnO coated cotton is loaded with 3 wt% rGO. In this work, the detailed mechanism of such absorption dominant EMI shielding has been discussed in details.

2D Ti3C2Tx MXene/polyvinylidene fluoride (PVDF) nanocomposites for attenuation of electromagnetic radiation with excellent heat dissipation

The present study deals with novel, and cost-effective preparation of 2D MXene (Ti3C2Tx) filled polyvinylidene fluoride (PVDF) polymer nanocomposite for the attenuation of electromagnetic interference (EMI). The obtained nanocomposite showed remarkable shielding effectiveness (SE) of 48.47 ± 3.5 dB for 22.55 vol% filler contents at a thickness of 2 mm. Formation of conducting network along with the assembly of micro capacitor network preserved for its high EMI shielding performance. The absorption dominated EMI shielding mechanism explained by the strong resonance, and interfacial polarization favors the loss of incident EM energy confirmed from dielectric measurements. Besides, the enhanced thermal conductivity of MXene-PVDF nanocomposites about 0.767 ± 0.034 Wm−1K−1 at 22.55 vol% filler content depicts that a large amount of incident EM wave attenuated majorly by dielectric components which would be dissipated as heat quickly. The fabricated MXene-PVDF nanocomposites could be a potential candidate for EMI shielding materials and promising multifaceted electronic utilization.

Ultra-light 3D reduced graphene oxide aerogels decorated with cobalt ferrite and zinc oxide perform excellent electromagnetic interference shielding effectiveness

In this study, three dimensional interconnected graphene aerogels decorated with cobalt ferrite nanoparticles and ZnO nanorods were prepared for the application of absorption dominant electromagnetic interference (EMI) shielding. Because of low density, high porosity and large surface area, the graphene aerogel showed total EMI shielding effectiveness of 25.07 dB at a thickness of 5 mm, which was further improved to 42.10 dB with the inclusion of cobalt ferrite nanoparticles. The incorporation of magnetic cobalt ferrite not only enhanced the total EMI shielding of the aerogels but also improved the power absorption from ∼37.738% to ∼87.788%. By further incorporating ZnO nanorods along with cobalt ferrite nanoparticles into the aerogels, the total EMI shielding effectiveness and power absorption enhanced to 48.56 dB and ∼93.655%, respectively. In this work, the EMI shielding performances of different samples are compared and the underlying mechanism of such excellent absorption dominant EMI shielding is discussed in detail.

A facile approach for coating Ti3C2Tx on cotton fabric for electromagnetic wave shielding

Electromagnetic interference (EMI) shielding fabric is widely used to deal with radiation pollution. However, the traditional EMI shielding fabrics are limited by their reflection-dominated shielding mechanism, large loading and poor shielding performance. Herein, Ti3C2Tx coated cotton fabrics with low Ti3C2Tx loading (1.5–2.6 mg/cm2) were prepared through a facile vacuum filtration process. Ti3C2Tx coated cotton fabric exhibits excellent electrical conductivity (up to 1570 S/cm), EMI SE (up to 48.9 dB) and superior shielding efficiency (up to 2969 dB cm2/g) with a low Ti3C2Tx loading (2.6 mg/cm2) in the frequency of 2–18 GHz. Especially, Ti3C2Tx coated cotton fabric shows high ratio of absorption shielding efficiency (SEA)/reflection shielding efficiency (SER) (> 9) in the frequency of 2–13.5 GHz, indicating that the dominant shielding mechanism of Ti3C2Tx coated cotton fabrics is microwave absorption of EM radiation. Additionally, the Ti3C2Tx coated cotton fabric exhibits a high tensile strength (up to 70 N) and fracture elongation (up to 18.3%). The result suggests that the Ti3C2Tx coated cotton fabric is a superior absorption-dominated EMI shielding material. The Ti3C2Tx coated cotton fabric with low loading, robust, and highly conductive properties can be regarded as an alternative electromagnetic wave absorbing material.

FeSiAl/metal core shell hybrid composite with high-performance electromagnetic interference shielding

Herein, for the first time, FeSiAl (sendust)/metal hybrid materials were synthesized with a magnetic core and a highly electrically conductive metal shell for shielding electromagnetic interference (EMI) pollution. Soft magnetic sendust flakes were electroless-plated with electrically conductive Ag or Ni metal to form Ag-plated and Ni-plated sendust core-shell hybrids. The magnetic and metal hybrid-incorporated paraffin wax composites exhibited a better absorption-dominant EMI shielding performance of 65.6 dB and 58.5 dB, respectively, than that of the sendust wax composite and the composite with a mixture of sendust and electrically conductive Ag/Cu dendrite. The superior shielding performance was attributed to the synergistic combination of the effective magnetic loss, dielectric loss, and conduction loss. These exceptional properties of the new hybrid composite showed that it could be used in absorption-dominant EMI shielding applications.

Quick Heat Dissipation in Absorption-Dominated Microwave Shielding Properties of Flexible Poly(vinylidene fluoride)/Carbon Nanotube/Co Composite Films with Anisotropy-Shaped Co (Flowers or Chains).

The facile fabrication of thin flexible electromagnetic interference (EMI) shielding materials with fast heat dissipation for adaptable tuning in both civil and military applications is in urgent demand. In our work, the flexible poly(vinylidene fluoride) (PVDF)/carbon nanotube (CNT) composite films decorated with anisotropy-shaped Co in flowers or chains were prepared and studied. The results showed that by increasing the Co filler contents, the EC (electrical conductivity), TC (thermal conductivity), and EMI shielding properties of such PVDF/CNT/Co (flowers or chains) flexible films were significantly improved. In contrast, the PVDF/CNT/Co-chain flexible films exhibit higher performance with respect to the EC, TC, and EMI shielding properties. Total shielding of 35.3 and 32.2 dB were, respectively, obtained by the PVDF/CNT/6 wt % Co-chain with an EC of 2.28 S/cm and the PVDF/CNT/6 wt % Co-flower with an EC of 1.94 S/cm at a film thickness of 0.3 mm. Possibly owing to the conductive dissipation, interfacial polarization, magnetic loss, multiple reflections, and scattering of EM waves, such flexible composite films possessed a remarkable absorption-dominated EMI shielding behavior. These new composite films with enhanced TC are easily able to transform microwave energy into Joule heating systems, making themselves greatly potential for effective EMI shielding as well as rapid heat dissipation.

Layer-Structured Design and Fabrication of Cyanate Ester Nanocomposites for Excellent Electromagnetic Shielding with Absorption-Dominated Characteristic.

In this work, we propose novel layer-structured polymer composites (PCs) for manipulating the electromagnetic (EM) wave transport, which holds unique electromagnetic interference (EMI) shielding features. The as-prepared PCs with a multilayered structure exhibits significant improvement in overall EMI shielding effectiveness (EMI SE) by adjusting the contents and distribution of electrical and magnetic loss fillers. The layer-structured PCs with low nanofiller content (5 wt % graphene nanosheets (GNSs) and 15 wt % Fe3O4) and a thickness of only 2 mm exhibited ultrahigh electrical conductivity and excellent EMI SE, reaching up to 2000 S/m and 45.7 dB in the X-band, respectively. The increased EMI SE of the layer-structured PCs was mainly based on the improved absorption rather than the reflection of electromagnetic waves, which was attributed to the “absorb-reflect-reabsorb” process for the incident electromagnetic waves. This work may provide a simple and effective approach to achieve new EMI shielding materials, especially for absorption-dominated EMI shielding.

On the absorption dominated EMI shielding effects in free standing and flexible films of poly(vinylidene fluoride)/graphene nanocomposite

The present work highlights the remarkably high electro-magnetic interference (EMI) shielding effectiveness of about 47 dB, exhibited by highly conducting and ordered poly(vinylidene fluoride) (PVDF)/graphene nanocomposite films of thickness around 20 µm, in the microwave frequency range 8–12 GHz, obtained by solution casting method. The films were characterized structurally using X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy and the analysis indicates the enhancement in the highly ordered β phase of PVDF with the incorporation of graphene. In the entire frequency range of analysis, by absorption loss to the total EMI shielding effectiveness is very high compared to that by reflection loss. The high electrical conductivity of the composite films promotes shielding by absorption losses which is of ample significance in stealth applications. The present results identify the PVDF/graphene nanocomposite film as an effective, lightweight, free standing, flexible, mechanically and thermally stable, absorption dominated EMI shielding material with application prospects in a broad range of electromagnetic spectrum. The shielding effectiveness of these highly conducting nanocomposite films, far exceeds most of the previously reported values and meets the commercial requirements. The freestanding and flexible nature of these films facilitates EMI shielding applications without the geometrical constraints of the shape or size of the object.

Polyaniline-coated SnO/Y2O3 Nanocomposites for Broadband EMI Shielding and Microwave Absorption

There is an ever increasing demand for high-performance electromagnetic interference (EMI) shielding materials due to the rapid proliferation of electro/electrical systems. Herein, we report the investigations on EMI shielding and microwave absorption properties of synthesized polyaniline-coated stannous oxide/yttrium trioxide (PAni/SnO/Y2O3) nanocomposites. The spectroscopic characterizations of the composites were performed using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanocomposites showed effective absorption dominant EMI shielding due to the modified electric and electromagnetic effect of the nanocomposites. The EMI shielding measurements were carried out in the frequency range of 12-18 GHz (Ku-Band), relevant for practical applications. The shielding analysis demonstrates the synergistic effect of the complementing phases (i.e. PAni, SnO and Y2O3) which leads to high shielding effectiveness (SE) in the range of –33 to –42.6 dB (< 99.9% attenuation). The absorption dominated shielding effectiveness and the possibility to tailor the properties of these nanocomposites by varying the concentration of dispersants content can be optimized for making effective broadband microwave shields.

Ku-band EMI shielding effectiveness and dielectric properties of Polyaniline-Y2O3 composites

Electromagnetic interference (EMI) shielding has become a phenomenon of great concern and there is growing demand towards the synthesis of materials with better EMI shielding effectiveness (EMI SE). This work highlights the preparation of Polyaniline-Yttrium Oxide (PANI-Y2O3) composites for EMI shielding applications in the frequency range from 12.4 to 18 GHz (Ku-band). The structure and morphology of the composites were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). EMI SE, microwave absorption and reflection, dielectric properties of the composites are discussed in detail. All the computations were based on microwave scattering parameters measured by transmission line waveguide technique. The observed results show absorption dominant EMI shielding in these composites with EMI SE of −19 to −20 dB, which mainly depends on the dielectric loss of the composites. Through the results of our observations, we propose these composites to be potential materials for microwave absorption and EMI shielding applications.

Effect of length of carbon nanotubes on electromagnetic interference shielding and mechanical properties of their reinforced epoxy composites

The high performance-multiwalled carbon nanotubes (MWCNTs) reinforced epoxy resin nanocomposites have been fabricated using industrially viable fast process of dispersion with high speed homogenizer (~30,000 rpm). This high energy homogenizer was found to be a successful technique for uniformly dispersion of MWCNTs and confirmed by scanning electron microscopy. Herein, two different lengths of MWCNTs, i.e., long length of ~350 μm aligned bundle (l-MWCNT) and short length of 1.5 μm (s-MWCNT) were used as reinforcement in epoxy resin. The effect of length of MWCNTs on the mechanical, electrical, and electromagnetic interference (EMI) shielding properties of MWCNTs/epoxy nanocomposites is investigated. The percolation threshold was obtained at 0.02 wt% for l-MWCNT compared to 0.11 for s-MWCNT. Due to very low percolation threshold and enhanced electrical conductivity (1.37 × 10−3 S cm−1 for 0.5 wt% l-MWCNT and 0.95 × 10−3 S cm−1 for 0.5 wt% s-MWCNT), absorption dominated EMI shielding effectiveness was achieved −16 dB for l-MWCNT compared to −11.5 dB for s-MWCNT with 0.5 wt% loading in Ku-band (12.4–18 GHz). This is the highest reported value for MWCNTs-epoxy composites for low loading level of 0.5 wt% at 2.5-mm thickness. In addition to this, flexural strength of the composites was found to be 125 MPa at 0.3 wt% for l-MWCNT and 113 MPa at 0.3 wt% for s-MWCNT from 95 MPa of pure cured epoxy suggesting the usefulness of this of material as strong microwave absorber.