The arrival of the 5G era has made electromagnetic pollution a problem that needs to be addressed, and flexible carbon-based materials have become a good choice. In this study, wet continuous papermaking technology was used to prepare carbon fiber paper (CFP) with a three-dimensional conductive skeleton network; Molybdenum disulfide ( MOS2)/ iron (Fe) @ carbon fiber paper-based shielding material was prepared by impregnating and blending molybdenum disulfide/iron ( MOS2/Fe) phenolic resin MOS2/ Fe@ CFP. The morphology, structure, electrical conductivity, mechanical properties, hydrophobicity, and electromagnetic shielding properties of the composite were characterized. The results show that the three-dimensional network structure based on a short carbon fiber paper-based conductive skeleton and the synergistic effect of the MOS2 dielectric wave absorbing agent and Fe magnetic wave absorbing agent have good electromagnetic shielding performance. Conduct electromagnetic shielding simulation using HFSS software to provide options for the structural design of CFP. The electromagnetic shielding performance of CFP reaches 70 dB, and the tensile strength reaches 34.39 MPa. Based on the mechanical properties, the compactness of carbon fiber paper is ensured. The lightning damage model test using CST software expands the direction for the use of carbon fiber paper. In summary, MOS2/ Fe @CFP with excellent shielding performance has great application prospects in thinner and lighter shielding materials, as well as high sensitivity, defense and military equipment.

탄소섬유 강화 플라스틱 (Carbon fiber reinforced plastics, CFRP)은 고함량의 탄소섬유 (Carbon fiber, CF)와 고분자로 이루어진 복합재료로서, 뛰어난 기계적 성능으로 항공우주, 자동차, 토목 등 다 양한 산업 분야에서 사용되고 있다. 하지만 사용량 증가에 따른 폐기물의 환경문제와 추출한 재활용 탄소섬유 (Recycled carbon fiber, rCF)의 적용 가능 분야의 한계로 인해 재활용이 제한적인 실정이 다. 본 연구에서는 rCF와 CF 혼입 시멘트계 전자파 복합재를 제작하여 그 성능을 비교 분석하기 위 한 실험을 수행하였다. 구성재료는 시멘트, 잔골재, 고성능 감수제를 사용하였으며, 비교 분석을 위해 CF와 rCF를 각각 6 mm, 12 mm 길이를 0.1, 0.3, 0.5, 1.0 wt.% 함량으로 사용하였다. 전자파 복합 재의 흡수 성능 향상을 위해 각각 다른 함량의 다층 구조를 형성하였으며, 전자파 투과를 낮은 함량에 서 높은 함량 방향이 되도록 측정을 진행하였다. 전자파 차폐성능은 재령 28일 이후 네트워크 분석기 를 사용하여 자유 공간에서 측정하였으며, C-band (4~8 GHz)와 X-band (8~12 GHz) 주파수 영역 에서의 반사율과 투과율을 각각 측정하였다.

Recent advancements in electronic devices and wireless communication technologies, particularly the rise of 5G, have raised concerns about the escalating electromagnetic pollution and its potential adverse impacts on human health and electronics. As a result, the demand for effective electromagnetic interference (EMI) shielding materials has grown significantly. Traditional materials face limitations in providing optimal solutions owing to inadequacy and low performance due to small thickness. MXene-based composite materials have emerged as promising candidates in this context owing to their exceptional electrical properties, high conductivity, and superior EMI shielding efficiency across a broad frequency range. This review examines the recent developments and advantages of MXene-based composite materials in EMI shielding applications, emphasizing their potential to address the challenges posed by electromagnetic pollution and to foster advancements in modern electronics systems and vital technologies.

Metals are recognized as electromagnetic interference (EMI) shielding materials owing to their high electrical conductivity. However, the need for light and flexible EMI shielding materials has emerged, owing to the heavyweight and inflexible nature of metals. Carbon nanotube (CNT)/polymer composites have been studied as promising flexible EMI shielding materials because of their lightweight nature due to the low density of CNTs and their high electrical conductivity. CNTs evenly dispersed in the polymer form an electrically conductive network, and the aspect ratio of the CNTs, which are one-dimensional nanofillers, is an important factor affecting electrical conductivity. In this study, we prepared three types of multi-walled carbon nanotubes (MWNTs) with different aspect ratios and fabricated polydimethylsiloxane (PDMS)/MWNT composites. Subsequently, the electrical conductivities and electrical percolation thresholds of the three PDMS/MWNT composites with different MWNT aspect ratios were measured to analyze the behavior of electrically conducting network formation according to the aspect ratio. Furthermore, the total EMI shielding effectiveness of each composite was determined to evaluate the effect of the MWNT aspect ratio on the EMI shielding. Reflection and absorption of electromagnetic wave were measured for the PDMS/MWNT composite with the largest aspect ratio to analyze the EMI shielding mechanism of the composite. Additionally, the effects of the MWNT content on the conductivity and EMI shielding performance were examined. The results provide valuable guidance for designing polymer MWNT composites with good electrical conductivity and EMI shielding performance under different aspect ratios of MWNTs.

Lightweight and flexible electromagnetic interference (EMI) shielding materials are in great demand for wearable EMI device. In the present work, lightweight and flexible carbon nanotube (CNT)/ferroferric oxide ( Fe3O4) composite film was made through a feasible chemical vapor deposition process for CNT film synthesis, followed by a hydrothermal reduction process for Fe3O4 coating. In the as-prepared composite, CNT film and Fe3O4 particles work as conductive skeleton and strong magnetic particle, respectively. The as-prepared composite film shows a novel EMI shielding effectiveness (SE) of 91 dB in the X-band, a small thickness of 0.09 mm and a low density of 0.86 g/cm3, which is superior to most of the carbonbased EMI materials.

Electromagnetic interference (EMI) shielding is an important issue in modern daily life due to the increasing prevalence of electronic devices and their compact design. This study estimated EMI-shielding effect (EMI-SE) of small (8–14×17 mm) Hanji (Korean traditional paper) doped with carbon nanotubes (CNTs) and compared to Hanji without CNT using 2H (92.1 MHz) and 23Na (158.7 MHz) nuclear magnetic resonance (NMR) peak area data obtained from 1 M NaCl in D2O samples in capillary tubes that were wrapped in the Hanji samples. The simpler method of using the variation of reflected power and tuning frequency by inserting the sample into an NMR coil was also tested at 242.9, 158.7, and 92.1 MHz. Overall, EMI shielding was relatively more effective at the higher frequencies. Our results validated that NMR methods to be useful to evaluate EMI-SE, particularly for small, flexible shielding materials, and demonstrated that EMI shielding by absorption is dominant in Hanji mixed with CNT.

The microstructure, flexural properties, electrical conductivity, thermal conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites filled with multi-walled carbon nanotubes (CNTs), exfoliated graphite nanoplatelets (xGnPs) and CNT-xGnP hybrid filler were investigated. The EMI SE of the CNT-xGnP hybrid composite was higher than 25 dB at 100 MHz while that of the xGnP based composite was almost zero. The flexural modulus of the CNT-xGnP based epoxy composite continuously increased to 3.32 GPa with combined filler content up to 10 wt% while that of the CNT based epoxy composites slightly decreased to 1.96 GPa at 4 wt% CNT, and dropped to 1.57 GPa at 5 wt% loading, which is lower than that of epoxy. The CNT and CNT-xGnP samples had the same EMI SE at the same surface resistivity, because samples with the same surface conductivity have the same amount of the charge carriers.

Electronic products are a major part of evolving industry and human life style; however most of them are known to emit electromagnetic waves that have severe health hazards. Therefore, different materials and fabrication techniques are understudy to control or limit transfer of such waves to human body. In this study, nanocomposite powder is dispersed into epoxy resin and shielding effects such as absorption, reflection, penetration and multiple reflections are investigated. In addition, nano size powder (Ni, Fe2O3, Fe-85Ni, C-Ni) is fabricated by pulsed wire evaporation method and dispersed manually into epoxy. Characterization techniques such as X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy are used to investigate the phase analysis, size and shape as well as dispersion trend of a nano powder on epoxy matrix. Shielding effect is measured by standard test method to investigate the electromagnetic shielding effectiveness of planar materials, ASTM D4935. At lower frequency, sample consisting nano-powder of Fe-85%Wt Ni shows better electromagnetic shielding effect compared to only epoxy, only Ni, Fe2O3 and C-Ni samples.

Recently, methods that usea carbon-based filler, a conductive nanomaterial, have been investigated to develop composite fillers containing dielectric materials. In this study, we added geometric changes to a carbon fiber, a typical carbon-based filler material, by differentiating the orientation angle and the number of plies of the fiber. We also studied the electrical and electromagnetic shield characteristics. Based on the orientation angle of 0˚, the orientation angle of the carbon fiber was changed between 0, 15, 30, 45, and 90˚, and 2, 4, and 6 plies were stacked for each orientation angle. The maximum effect was found when the orientation angle was 90˚, which was perpendicular to the electromagnetic wave flow, as compared to 0˚, in which case the electrical resistance was small. Therefore, it is verified that the orientation angle has more of an effect on the electromagnetic interference shield performance than the number of plies.

The automotive industry is moving from the internal combustion engine to electric drive motors. Electricmotors uses a high voltage system requiring the development of resources and components to shield the system. There-fore, in this study, we analyze electromagnetic interference (EMI) shielding effectiveness (SE) characteristics of an autocrash pad according to the ratio of electrically conductive materials and propylene. In order to combine good mechan-ical characteristics and electromagnetic shielding of the automotive crash pad, metal-coated glass fiber (MGF) manufac-turing methods are introduced and compared with powder-type methods. Through this study, among MGF methods, wesuggest that the chopping method is the most effective shielding method.

The conducting polymer-coated multi-walled carbon nanotubes (MWCNTs) were prepared by template polymerization of aniline and pyrrole on the surface of MWCNTs in order to develop the novel electromagnetic interference (EMI) shielding materials. The conducting polymer phases formed on the surface of MWCNTs were confirmed by field emission-scanning electron microscopy and field emission-transmission electron microscopy. Both permittivity and permeability were significantly improved for the conducting polymer-coated MWCNTs due to the intrinsic electrical properties of MWCNTs and the conducting properties of coated polymers. The electromagnetic waves were effectively absorbed based on the permittivity nature of conducting polymer and MWCNTs preventing the secondary interference from reflecting the electromagnetic waves. The highly improved EMI shielding efficiency was also obtained for the conducting polymer-coated MWCNTs showing the synergistic effects by combining MWCNTs and the conducting polymers.

Carbon blacks could be used as the filler for the electromagnetic interference (EMI) shielding. The poly vinyl alcohol (PVA) and polyvinylidene fluoride (PVDF) were used as the matrix for the carbon black fillers. Porous carbon blacks were prepared by CO2 activation. The activation was performed by treating the carbon blacks in CO2 to different degrees of burnoff. During the activation, the enlargement of pore diameters, and development of microporous and mesoporous structures were introduced in the carbon blacks, resulting in an increase of extremely large specific surface areas. The porosity of carbon blacks was an increasing function of the degree of burn-off. The surface area increased from 80 m2/g to 1142 m2/g and the total pore volume increased from 0.14073 cc·g-1 to 0.9343 cc·g-1. Also, the C=O functional group characterized by aldehydes, ketones, carboxylic acids and esters was enhanced during the activation process. The EMI shielding effectiveness (SE) of raw N330 carbon blacks filled with PVA was about 1 dB and those of the activated carbon blacks increased to the values between 6 and 9 dB. The EMI SE of raw N330 carbon blacks filled with PVDF was about 7 dB and the EMI SE increased to the range from 11 to 15 dB by the activation.

전자파 차폐특성 측정방법의 일환으로 매질의 전기전도도로부터 차폐효과를 정성적 수준에서 예측하는 연구를 수행하였다. 사용된 시편은 전도성 금속 (Cu, Ni)이 피복된 망사형 차폐재로 두께는 0.1 mm 정도이고, 전기전도도는 6.4×10~2.4×10(sup)5 mhos/m 범위 값을 가졌다. 물질상수와 시편의 두께로 표시되는 반사손실 및 흡수손실의 이론식을 도출하고 상기 시편에 대해 차폐효과를 계산하였다. 전도성 피복재의 경우 주된 차폐기구는 반사손실임을 밝힐 수 있었으며, 전기전도도가 증가함에 따라 차폐효과는 현저히 증가함을 알 수 있었다. 이들 이론치를 임피던스 실측치로부터 계산된 반사손실과 비교한 결과 10 dB 이내의 오차를 보임으로써 제안한 분석방법의 타당성을 입증하였다.

이 연구는 고성능 섬유보강 복합체(HPFRCC)의 전자파 차폐성능을 향상시키기 위한 목적으로 전기전도도, 전자파 차폐능, 역학적 강도를 조사하였다. 강섬유, 제강슬래그 미분말, 카본블랙이 전도성재료소 HPFRCC 배합에 첨가되었다. 또한, MWCNT를 수 분산 시켜 제조된 2% wt. CNT 용액을 사용하였다. 실험 결과, HPFRCC의 전기전도도는 1% 카본블랙이 첨가된 시편을 제외하고는 매우 낮은 특성을 보였다. 시멘트 매트릭스의 미세구조는 시간에 따라 변하였고, 그로 인해 HPFRCC의 전기전도성 네트워크에 부정적인 영향을 끼쳤다. 0.083 S/cm의 전도도를 갖는 HC1 시편의 경우, 수분에 의한 효과를 배제하기 위하여 72시간 60도에서 건조 양생한 후에 측정한 전기전도도가 0.0003 S/cm로 상당히 감소하였다. 전자파 차폐 성능에 가장 중요한 인자는 강섬유인 것으로 나타났으며, 반면 카본블랙과 제강슬래그 미분말의 효과는 미미하였다. 전기전도도와 전자파 차폐능의 상관관계는 이 연구에서는 뚜렸한 경향성을 나타내지는 않았다.

In this study, it evaluate the electromagnetic pulse shielding performance of fiber reinforced cement composite by Fiber type. Hooked-ended steel fiber, Smooth steel fiber and Amorphous metallic fiber were reinforced 2.0 vol.% in cement composites respectively. The electromagnetic pulse shielding performance was evaluated by MIL-STD-188-125-1.

최근 새로 지어진 모든 건물들은 스마트빌딩으로 지어지고, 도로 또한 첨단도로로 시스템이 변하면서 도시자체가 스마트화로 변해가고 있다. 이러한 스마트 도시는 각각의 수많은 센서로 이루어져 있지만, 정작 EMP(Electro Magnetic Pulse)와 같은 전자기파동에 취약한 점이 있다. 위와 같은 전자기펄스를 방호하가 위해 본 연구에서는 다중벽 탄소나노튜브(MWCNT)를 활용하여 시멘트와 혼합하였으며, MWCNT의 함량은 2.5wt%에서 15wt%까지 달리하여 모르타르 공시체를 만들어 전자파 차폐 효과 및 강도에 미치는 영향에 대해서 살펴보았다. 본 실험을 통해 MWCNT의 함량이 전자기펄스 차단에 효과적이란 것을 확인 하였으며, MWCNT의 함량이 높을수록 전자기펄스의 차폐효과가 높아진다는 것을 확인하였다. 또한 모르타르의 강도에서도 초반 5wt%의 함량 까지는 높은 수치를 보였으나 함량이 클수록 낮은 강도를 보였다. 이는 MWCNT가 서로 뭉치는 성질로 인해 강도를 감소시킨 것으로 판단된다.