In-situ growth of MAX phase coatings on carbonised wood and their terahertz shielding properties

AbstractElectromagnetic interference (EMI) shielding materials have received considerable attention in recent years. The EMI shielding effectiveness (SE) of materials depends on not only their composition but also their microstructures. Among various microstructure prototypes, porous structures provide the advantages of low density and high terahertz wave absorption. In this study, by using carbonised wood (CW) as a template, 1-mm-thick MAX@CW composites (Ti2AlC@CW, V2AlC@CW, and Cr2AlC@CW) with a porous structure were fabricated through the molten salt method. The MAX@CW composites led to the formation of a conductive network and multilayer interface, which resulted in improved EMI SE. The average EMI SE values of the three MAX@CW composites were > 45 dB in the frequency of 0.6–1.6 THz. Among the composites, V2AlC@CW exhibited the highest average EMI SE of 55 dB.

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In-situ Growth of MAX Phase Coatings on Ecological Carbon and their Terahertz Shielding Properties Investigations

10.21203/rs.3.rs-376940/v1 ◽

2021 ◽

Author(s):

Jiaxuan Huang ◽

Hujie Wan ◽

Mian Li ◽

Yiming Zhang ◽

Jianfeng Zhu ◽

...

Keyword(s):

Porous Structure ◽

Electromagnetic Interference ◽

Max Phase ◽

Molten Salt Method ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Average Value ◽

Emi Shielding Effectiveness ◽

Carbonized Wood

Abstract Electromagnetic interference (EMI) shielding materials have received great interests in recent years. The EMI shielding effectiveness (SE) of materials not only depends on their composition, but also is influenced by their microstructures. Among various microstructure prototypes, porous structure has special advantage of low density and high electromagnetic wave reflections ability. Herein, a MAX@CW composite (Ti2AlC@CW, V2AlC@CW, Cr2AlC@CW) with porous structure is fabricated through a molten salt method by using carbonized wood (CW) as template. The MAX@CW forms conductive network constructions and rich interface that can further improve the EMI shielding effectiveness. The average EMI shielding effectiveness of the three kinds of MAX@CW with the thickness of 1 mm are higher than 45 dB in the frequency range of 0.6 ~ 1.6 THz. Among them, V2AlC@CW show the best EMI shielding effectiveness with the average value of 55 dB.

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Ultrathin, Lightweight, and Flexible CNT Buckypaper Enhanced Using MXenes for Electromagnetic Interference Shielding

Nano-Micro Letters ◽

10.1007/s40820-021-00597-4 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Rongliang Yang ◽

Xuchun Gui ◽

Li Yao ◽

Qingmei Hu ◽

Leilei Yang ◽

...

Keyword(s):

Electromagnetic Interference ◽

High Performance ◽

Electronic Devices ◽

Deposition Process ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Emi Shielding Effectiveness ◽

X Band ◽

Wearable Electronic Devices ◽

Emi Se

AbstractLightweight, flexibility, and low thickness are urgent requirements for next-generation high-performance electromagnetic interference (EMI) shielding materials for catering to the demand for smart and wearable electronic devices. Although several efforts have focused on constructing porous and flexible conductive films or aerogels, few studies have achieved a balance in terms of density, thickness, flexibility, and EMI shielding effectiveness (SE). Herein, an ultrathin, lightweight, and flexible carbon nanotube (CNT) buckypaper enhanced using MXenes (Ti3C2Tx) for high-performance EMI shielding is synthesized through a facile electrophoretic deposition process. The obtained Ti3C2Tx@CNT hybrid buckypaper exhibits an outstanding EMI SE of 60.5 dB in the X-band at 100 μm. The hybrid buckypaper with an MXene content of 49.4 wt% exhibits an EMI SE of 50.4 dB in the X-band with a thickness of only 15 μm, which is 105% higher than that of pristine CNT buckypaper. Furthermore, an average specific SE value of 5.7 × 104 dB cm2 g−1 is exhibited in the 5-μm hybrid buckypaper. Thus, this assembly process proves promising for the construction of ultrathin, flexible, and high-performance EMI shielding films for application in electronic devices and wireless communications.

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Carbonization of Graphene-Doped Isocyanate-Based Polyimide Foams to Achieve Carbon Foams with Excellent Electromagnetic Interference Shielding Performance

Materials ◽

10.3390/ma14247551 ◽

2021 ◽

Vol 14 (24) ◽

pp. 7551

Author(s):

Hui Jing ◽

Zongnan Miao ◽

Zhong Zeng ◽

Hui Liu ◽

Shengtai Zhou ◽

...

Keyword(s):

Electrical Conductivity ◽

Electromagnetic Interference ◽

Carbonization Temperature ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Emi Shielding Effectiveness ◽

Graphitization Degree ◽

Carbon Foams ◽

Potential Applications ◽

Emi Se

Lightweight carbon foams with excellent electromagnetic interference (EMI) shielding performance were prepared by carbonization process, using isocyanate-based polyimide foams as carbon precursors. The influence of carbonization temperature and graphene-doping on the morphological, electrical and EMI shielding effectiveness (SE) of corresponding carbon foams was studied in detail. Results showed that the addition of graphene was beneficial to the improvement of electrical conductivity and EMI shielding performance of carbon foams. The electrical conductivity of carbon foams increased with the carbonization temperature which was related to the increase of graphitization degree. Collapse of foam cells was observed at higher carbonization temperatures, which was detrimental to the overall EMI SE. The optimal carbonization temperature was found at 1100 °C and the carbon foams obtained from 0.5 wt% graphene-doped foams exhibited a specific EMI SE of 2886 dB/(g/cm3), which shows potential applications in fields such as aerospace, aeronautics and electronics.

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Flexible GnPs/EPDM with Excellent Thermal Conductivity and Electromagnetic Interference Shielding Properties

NANO ◽

10.1142/s1793292019500759 ◽

2019 ◽

Vol 14 (06) ◽

pp. 1950075 ◽

Cited By ~ 2

Author(s):

Shaowei Lu ◽

Yaoyao Bai ◽

Jijie Wang ◽

Dandan Chen ◽

Keming Ma ◽

...

Keyword(s):

Thermal Conductivity ◽

Electromagnetic Interference ◽

Rubber Matrix ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Emi Shielding Effectiveness ◽

X Band ◽

Cost Efficient ◽

Emi Se ◽

Shielding Material

As the portable device hardware has been increasing at a noticeable rate, ultrathin flexible materials with the combination of high thermal conductivity and excellent electromagnetic interference (EMI) shielding performance are urgently needed. Here, we fabricated ethylene propylene diene monomer rubber with different loading graphene nanoplatelets (GnPs/EPDM) by a cost-efficient approach, which combines mixing, ultrasonication and compression. Further investigation demonstrates that the 8[Formula: see text]wt.% GnPs/EPDM with only 0.3[Formula: see text]mm in thickness shows excellent electrical conductivity (28.3[Formula: see text]S/m), thermal conductivity (0.79[Formula: see text]W/m[Formula: see text]K) and good mechanical properties. Besides, the 8[Formula: see text]wt.% GnPs/EPDM exhibits an EMI shielding effectiveness (SE) up to 33[Formula: see text]dB in the X-band (8.2–12.4[Formula: see text]GHz) and 35[Formula: see text]dB in the Ku-band (12.4–18[Formula: see text]GHz), superior to most of the reported rubber matrix. Additionally, the GnPs/EPDM shows excellent flexibility and stability with 95% and 94% retention of EMI SE even after repeated bending for 5000 times and corrosion (under 5% NaCl environment) for a week. Our flexible EMI shielding material will benefit the fast-growing next-generation commercial portable flexible electrons.

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

Polymers ◽

10.3390/polym10090933 ◽

2018 ◽

Vol 10 (9) ◽

pp. 933 ◽

Cited By ~ 4

Author(s):

Fang Ren ◽

Zheng-Zheng Guo ◽

Han Guo ◽

Li-Chuan Jia ◽

Yu-Chen Zhao ◽

...

Keyword(s):

Electromagnetic Interference ◽

Electromagnetic Waves ◽

Graphene Nanosheets ◽

Magnetic Loss ◽

Multilayered Structure ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Emi Shielding Effectiveness ◽

Wave Transport ◽

Emi Se

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.

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Mesocarbon microsphere composites with Fe3O4 nanoparticles for outstanding electromagnetic interference shielding effectiveness

RSC Advances ◽

10.1039/c5ra03332b ◽

2015 ◽

Vol 5 (54) ◽

pp. 43279-43289 ◽

Cited By ~ 23

Author(s):

Ridham Dhawan ◽

Saroj Kumari ◽

Rajeev Kumar ◽

S. K. Dhawan ◽

Sanjay R. Dhakate

Keyword(s):

Fe3o4 Nanoparticles ◽

Electromagnetic Interference ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Electromagnetic Interference Shielding ◽

Emi Shielding Effectiveness ◽

Electromagnetic Interference Shielding Effectiveness

In situ, development of mesocarbon microsphere (MCMS) composites with magnetic Fe3O4 nanoparticles for outstanding electromagnetic (EMI) shielding effectiveness.

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Polyaniline-Stannous Oxide Composites: Novel Material for Broadband EMI Shielding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.488-489.557 ◽

2012 ◽

Vol 488-489 ◽

pp. 557-561 ◽

Cited By ~ 8

Author(s):

Muhammad Faisal ◽

Syed Khasim

Keyword(s):

Electromagnetic Interference ◽

Chemical Oxidation ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Practical Applications ◽

Stannous Oxide ◽

Emi Shielding Effectiveness ◽

X Band ◽

Potential Applications ◽

Emi Se

Insitu polymerization of aniline was carried out in the presence of stannous oxide (SnO) to synthesize Polyaniline (PAni)/SnO composites by chemical oxidation method. The surface morphology of the composites were studied by scanning electron microscopy (SEM).The electromagnetic interference (EMI) shielding properties of the composites were investigated for different wt % of SnO (10,20,30,40 and 50 wt%) in PAni. The EMI measurements were carried out in the frequency range from 8.2 to 12.4 GHz (X-band), which is relevant for practical applications. EMI shielding effectiveness (EMI SE), microwave absorption and reflection, the influence of SnO concentration in PAni on EMI SE of the composites are reported. The composites exhibit EMI SE value of -18 to -23 dB. The absorption dominated EMI SE of these composites indicates the potential applications of these materials for microwave attenuation in the X-band.

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Hybrid Nanocomposite Material for EMI Shielding in Spacecrafts

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1101.46 ◽

2015 ◽

Vol 1101 ◽

pp. 46-50 ◽

Cited By ~ 2

Author(s):

Fawad Tariq ◽

Madni Shifa ◽

Mateen Tariq ◽

S. Kazim Hasan ◽

Rasheed Ahmed Baloch

Keyword(s):

Electrical Conductivity ◽

Electromagnetic Interference ◽

Hybrid Nanocomposite ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Frequency Range ◽

Multiwalled Carbon ◽

Emi Shielding Effectiveness ◽

The Matrix ◽

Emi Se

In this study lightweight carbon fiber and multiwalled carbon nanotubes filled hybrid nanocomposite was fabricated for electromagnetic interference (EMI) shielding in spacecraft. Electrical conductivity was conducted to assess the affect of MWCNT addition on composite. EMI shielding effectiveness (SE) was tested in the frequency range of 1-18 GHz. Comparison of SE was also made with AA6061-T6 sheet. Dispersion of nanotubes in the matrix was examined through microscopy. Results indicated that the conductivity was increased with increasing MWCNTs up to 0.25 wt%. Higher loading level of MWCNTs has resulted in decrease in conductivity due to agglomeration in cured samples. Hybrid nanocomposite exhibited improved SE than AA6061-T6 in 1-8 GHz frequency range. Best SE and electrical conductivity was witnessed in 0.25 wt% MWCNT sample. EMI SE in range of-20 dB to-40 dB can be easily achieved in our developed material.

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A Healable and Mechanically Enhanced Composite with Segregated Conductive Network Structure for High-Efficient Electromagnetic Interference Shielding

Nano-Micro Letters ◽

10.1007/s40820-021-00693-5 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Ting Wang ◽

Wei-Wei Kong ◽

Wan-Cheng Yu ◽

Jie-Feng Gao ◽

Kun Dai ◽

...

Keyword(s):

Electromagnetic Interference ◽

Diels Alder ◽

Electrostatic Attraction ◽

List Type ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Electromagnetic Interference Shielding ◽

Elongation At Break ◽

High Efficient ◽

Emi Se

Highlights The cationic waterborne polyurethanes microspheres with Diels-Alder bonds were synthesized for the first time. The electrostatic attraction not only endows the composite with segregated structure to gain high electromagnetic-interference shielding effectiveness, but also greatly enhances mechanical properties. Efficient healing property was realized under heating environment. Abstract It is still challenging for conductive polymer composite-based electromagnetic interference (EMI) shielding materials to achieve long-term stability while maintaining high EMI shielding effectiveness (EMI SE), especially undergoing external mechanical stimuli, such as scratches or large deformations. Herein, an electrostatic assembly strategy is adopted to design a healable and segregated carbon nanotube (CNT)/graphene oxide (GO)/polyurethane (PU) composite with excellent and reliable EMI SE, even bearing complex mechanical condition. The negatively charged CNT/GO hybrid is facilely adsorbed on the surface of positively charged PU microsphere to motivate formation of segregated conductive networks in CNT/GO/PU composite, establishing a high EMI SE of 52.7 dB at only 10 wt% CNT/GO loading. The Diels–Alder bonds in PU microsphere endow the CNT/GO/PU composite suffering three cutting/healing cycles with EMI SE retention up to 90%. Additionally, the electrostatic attraction between CNT/GO hybrid and PU microsphere helps to strong interfacial bonding in the composite, resulting in high tensile strength of 43.1 MPa and elongation at break of 626%. The healing efficiency of elongation at break achieves 95% when the composite endured three cutting/healing cycles. This work demonstrates a novel strategy for developing segregated EMI shielding composite with healable features and excellent mechanical performance and shows great potential in the durable and high precision electrical instruments.

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Electromagnetic interference shielding effectiveness of polypyrrole-silver nanocomposite films on silane-modified flexible sheet

High Performance Polymers ◽

10.1177/09540083211064535 ◽

2021 ◽

pp. 095400832110645

Author(s):

Karim Benzaoui ◽

Achour Ales ◽

Ahmed Mekki ◽

Abdelhalim Zaoui ◽

Boudjemaa Bouaouina ◽

...

Keyword(s):

Surface Treatment ◽

Electromagnetic Interference ◽

Nanocomposite Films ◽

Electrical Characteristics ◽

Shielding Effectiveness ◽

Emi Shielding ◽

Electromagnetic Interference Shielding ◽

Silver Nanocomposite ◽

Electromagnetic Interference Shielding Effectiveness ◽

Emi Se

The conventional electromagnetic interference (EMI) shielding materials are being gradually replaced by a new generation of supported conducting polymer composites (CPC) films due to their many advantages. This work presents a contribution on the effects of silane surface–modified flexible polypyrrole-silver nanocomposite films on the electromagnetic interference shielding effectiveness (EMI-SE). Thus, the UV-polymerization was used to in-situ deposit the PPy-Ag on the biaxial oriented polyethylene terephthalate (BOPET) flexible substrates whose surfaces were treated by 3-aminopropyltrimethoxysilane (APTMS). X-ray Photoelectron Spectroscopy (XPS) analyzes confirmed the APTMS grafting procedure. Structural, morphological, thermal, and electrical characteristics of the prepared films were correlated to the effect of substrate surface treatment. Thereafter, EMI-SE measurements of the elaborated films were carried out as per ASTM D4935 standard for a wide frequency band extending from 50 MHz to 18 GHz. The obtained results confirmed that the APTMS-treated BOPET film exhibit higher EMI shielding performance and better electrical characteristics compared to the untreated film. In fact, a 32% enhancement of EMI-SE was noted for the treated films compared to the untreated ones. Overall, these results put forward the role played by the surface treatment in strengthening the position of flexible PPy-Ag supported films as high-performance materials in electronic devices and electromagnetic interference shielding applications.

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