scholarly journals Directional Electromagnetic Interference Shielding Based on Step-Wise Asymmetric Conductive Networks

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Bai Xue ◽  
Yi Li ◽  
Ziling Cheng ◽  
Shengdu Yang ◽  
Lan Xie ◽  
...  
Keyword(s):  
Self Assembly ◽  
Electromagnetic Interference ◽  
Research Field ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Multiwalled Carbon ◽  
Literature Report ◽  
Asymmetric Structures ◽  
Emi Shielding Effectiveness ◽  
New Research

AbstractSome precision electronics such as signal transmitters need to not only emit effective signal but also be protected from the external electromagnetic (EM) waves. Thus, directional electromagnetic interference (EMI) shielding materials (i.e., when the EM wave is incident from different sides of the sample, the EMI shielding effectiveness (SE) is rather different) are strongly required; unfortunately, no comprehensive literature report is available on this research field. Herein, Ni-coated melamine foams (Ni@MF) were obtained by a facile electroless plating process, and multiwalled carbon nanotube (CNT) papers were prepared via a simple vacuum-assisted self-assembly approach. Then, step-wise asymmetric poly(butylene adipate-co-terephthalate) (PBAT) composites consisting of loose Ni@MF layer and compact CNT layer were successfully fabricated via a facile solution encapsulation approach. The step-wise asymmetric structures and electrical conductivity endow the Ni@MF/CNT/PBAT composites with unprecedented directional EMI shielding performances. When the EM wave is incident from Ni@MF layer or CNT layer, Ni@MF-5/CNT-75/PBAT exhibits the total EMI SE (SET) of 38.3 and 29.5 dB, respectively, which illustrates the ΔSET of 8.8 dB. This work opens a new research window for directional EMI shielding composites with step-wise asymmetric structures, which has promising applications in portable electronics and next-generation communication technologies.

Flexible, conductive, porous, fibrillar polymer–gold nanocomposites with enhanced electromagnetic interference shielding and mechanical properties

2017 ◽  
Vol 5 (5) ◽  
pp. 1095-1105 ◽  
Author(s):  
Jun Li ◽  
Hu Liu ◽  
Jiang Guo ◽  
Zhen Hu ◽  
Zhijiang Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gold Nanoparticles ◽  
Self Assembly ◽  
Electromagnetic Interference ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Emi Shielding Effectiveness ◽  
Conductive Nanocomposites ◽  
Gold Nanocomposites

Flexible lightweight conductive nanocomposites prepared by self-assembly of gold nanoparticles on charged polymer nanofibers show enhanced EMI shielding effectiveness and mechanical properties.

Graphene Films for Flexible EMI Shielding Materials with Cross-Linked Structure via Reaction with Diamine Monomers

NANO ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. 2050157
Author(s):  
Shaofeng lin ◽  
Qing Zheng ◽  
Bowen Lei ◽  
Jianwei Zhang ◽  
Dazhi Jiang
Keyword(s):  
Electrical Conductivity ◽  
Self Assembly ◽  
Electromagnetic Interference ◽  
Nitrogen Doping ◽  
Graphene Film ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Xps Spectra ◽  
Emi Shielding Effectiveness ◽  
Graphene Films

Three kinds of diamine monomers [ethylenediamine, butylenediamine and [Formula: see text]-phenylenediamine (PPD)] are adopted to cross-link carboxylated graphene (GP-COOH) sheets through filtration with a vacuum-assisted self-assembly technique, to fabricate highly conductive and excellent electromagnetic interference (EMI) shielding films. XRD spectroscopy of cross-linked graphene films exhibits higher interlayer [Formula: see text]-spacing than the GP-COOH film. Results of FTIR and XPS spectroscopies indicate that diamine monomers are chemically grafted to the GP-COOH sheets through nucleophilic substitution reactions. Compared with that of the GP-COOH film, electrical conductivity of the PPD-cross-linked graphene film (GP-PPD) is remarkably improved from 69.7[Formula: see text]S/cm to 248.6[Formula: see text]S/cm, attributed to the decrease of junction contact resistance between adjacent graphene sheets, nitrogen doping effect and repair of defects. Higher nitrogen content and C/O ratio are observed in the XPS spectra of the GP-PPD film, leading to higher electrical conductivity than the remaining two amine-modified graphene films. The GP-PPD film also demonstrates excellent EMI shielding performance, with EMI shielding effectiveness (SE) of 26.5 dB at a thickness of 12.5[Formula: see text][Formula: see text]m, which is also better than the others. The outstanding EMI performance of the PPD-cross-linked graphene film is mainly ascribed to the enhanced electrical conductivity and modified electronic structure with nitrogen doping.

Hybrid Nanocomposite Material for EMI Shielding in Spacecrafts

2015 ◽  
Vol 1101 ◽  
pp. 46-50 ◽  
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.

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

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.

scholarly journals Electromagnetic Interference Shielding Performance Enhancement of Stretchable Transparent Conducting Silver Nanowire Networks with Graphene Encapsulation

2021 ◽  
Author(s):  
Siyi Yan ◽  
Peng Li ◽  
Zhongshi Ju ◽  
He Chen ◽  
Jiangang Ma
Keyword(s):  
Electromagnetic Interference ◽  
Performance Enhancement ◽  
Mechanical Stability ◽  
Silver Nanowire ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Dielectric Polarization ◽  
Emi Shielding Effectiveness ◽  
Graphene Films ◽  
Transparent Conducting

Abstract Silver nanowire (AgNW) networks are promising transparent conducting materials for electromagnetic interference (EMI) shielding and diverse optoelectronic devices. However, the poor contact between adjacent AgNWs leads to low electrical conductivity and weak mechanical stability of AgNW networks, which are limiting the practical application of these electronics. Here we report an efficient strategy to improve the overall performance of AgNW networks, in which the AgNW networks are sandwiched between two layers of graphene films. The graphene films improve the contact of overlapped AgNWs and bridge the discrete AgNWs, and thus increase the conductivity of graphene/AgNWs/graphene (GAG) films. Microwave permittivity measurements together with mechanism analyses reveal that the graphene films can enhance the EMI shielding effectiveness of AgNW networks through offering extra conduction loss, multiple dielectric polarization centers and multi-reflection processes. As a result, the GAG film with an average transmittance of 88% exhibits a sheet resistance lower than 15 Ω sq− 1 and an EMI shielding effectiveness of 31 dB (in the frequency range of 8.2‒12.4 GHz) after repeated stretching and release at a strain of 40%. Such a total performance is superior to that of most of as-reported transparent conductors. The GAG films therefore show application potential in the age of Internet of Things that electromagnetic radiation pollutions are everywhere.

EMI Shielding Properties of Polymer Blend with the Inclusion of Graphene Nano Platelets

2021 ◽  
Vol 875 ◽  
pp. 160-167
Author(s):  
Muhammad Fayzan Shakir ◽  
Asra Tariq
Keyword(s):  
Electromagnetic Interference ◽  
Coaxial Cable ◽  
Network Analyzer ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Electrically Conductive ◽  
Emi Shielding Effectiveness ◽  
Increasing Trend ◽  
Shielding Properties ◽  
Basic Prediction

Polymer nano composites based on poly vinyl chloride matrix were fabricated using polyaniline (PANI) and graphene nano platelets (GNP) as electrically conductive nano filler for the application of electromagnetic interference (EMI) shielding. DC conductivity was first evaluated by using cyclic voltammetry and found an increasing trend of electrical conductivity as PANI and GNP was added in PVC matrix that confirms the formation of electrically conductive network structure. Dielectric properties like dielectric constant, dielectric loss and AC conductivity were evaluated in frequency range of 100 Hz to 3 MHz that gives basic prediction for EMI shielding effectiveness. Vector Network Analyzer (VNA) was used to assess EMI shielding properties using coaxial cable method in 11GHz to 20GHz range and it was found that a maximum of 29 dB shielding was archived with the incorporation of 15 wt% of PANI in PVC. This value increased to 56 dB as 5 wt% GNP added in PVC/PANI 15 wt% blend. Interaction of matrix with filler, nature of filler and dispersion of filler in matrix are the key parameters for achieving high shielding effectiveness.

CNT@PDMS/NW composite materials with superior electromagnetic shielding

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Zi-Jing Zhou ◽  
Zhen-Xing Wang ◽  
Xiao-shuai Han ◽  
Jun-Wen Pu
Keyword(s):  
Electromagnetic Interference ◽  
Cellulose Nanofibers ◽  
Original Structure ◽  
Impregnation Method ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Band Frequency ◽  
Conductive Composites ◽  
Emi Shielding Effectiveness ◽  
Xrd Patterns

Abstract Lightweight materials with high electrical conductivity and hydrophobic mechanical properties are ideal materials for electromagnetic interference (EMI) shielding. Herein, the conductive composites with great EMI shielding effectiveness (SE) were successfully obtained by introducing multi-walled carbon nanotube (CNT) and polydimethylsiloxane (PDMS) based on the original structure of natural wood (NW). CNT@PDMS/NW composites were prepared via vacuum-pulse impregnation method and characterized by Fourier transform infrared (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) patterns, hydrophobicity analysis, and EMI shielding performance. As demonstrated, CNT nanosheets were successfully inserted into wood matrices, and hydrogen bonding between CNT nanosheets and cellulose nanofibers induced the fabrication of CNT@PDMS/NW composites. CNT@PDMS/NW composites exhibited excellent EMI SE values of 25.2 dB at the X-band frequency.

Freestanding Fe3O4 / Ti3C2Tx MXene / polyurethane composite film with efficient electromagnetic shielding and ultra-stretchable performance

2022 ◽  
Author(s):  
Yongqin Hu ◽  
Chen Hou ◽  
Yuxia Shi ◽  
Jiamei Wu ◽  
Da Yang ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Tensile Elongation ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
Polyurethane Composite ◽  
Human Reproductive ◽  
Interfacial Scattering

Abstract Electromagnetic pollution seriously affects the human reproductive system, cardiovascular system, people’s visual system, and so on. A novel versatile stretchable and biocompatible electromagnetic interference (EMI) shielding film has been developed, which could effectively attenuate electromagnetic radiation. The EMI shielding film was fabricated with a convenient solution casting and steam annealing with 2D MXene, iron oxide nanoparticles, and soluble polyurethane. The EMI shielding effectiveness is about 30.63 dB at 8.2 GHz, based on its discretized interfacial scattering and high energy conversion efficiency. Meanwhile, the excellent tensile elongation is 30.5%, because of the sliding migration and gradient structure of the nanomaterials doped in a polymer matrix. In addition, the film also demonstrated wonderful biocompatibility and did not cause erythema and discomfort even after being attached to the arm skin over 12 hours, which shows the great potential for attenuation of electromagnetic irradiation and protection of human health.

Facile fabrication of ultrathin graphene film with ultrahigh electrical conductivity and superb electromagnetic interference shielding effectiveness

2021 ◽  
Vol 9 (1) ◽  
pp. 214-222
Author(s):  
Xiaojing Liu ◽  
Wenyu Wu ◽  
Bin Guo ◽  
Minghao Cui ◽  
Huaxin Ma ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Self Assembly ◽  
Electromagnetic Interference ◽  
Graphene Film ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Graphene Films ◽  
Facile Fabrication ◽  
Electromagnetic Interference Shielding Effectiveness

Graphene films prepared through a self-assembly of graphene oxide and its derivatives have been recently explored for electromagnetic interference (EMI) shielding applications.

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