scholarly journals Layered Foam/Film Polymer Nanocomposites with Highly Efficient EMI Shielding Properties and Ultralow Reflection

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Li Ma ◽  
Mahdi Hamidinejad ◽  
Biao Zhao ◽  
Caiyun Liang ◽  
Chul B. Park
Keyword(s):  
Electromagnetic Interference ◽  
High Efficiency ◽  
Wave Attenuation ◽  
Impedance Matching ◽  
Film Structure ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Multiple Reflections ◽  
Emi Shielding Effectiveness ◽  
Foam Film

AbstractLightweight, high-efficiency and low reflection electromagnetic interference (EMI) shielding polymer composites are greatly desired for addressing the challenge of ever-increasing electromagnetic pollution. Lightweight layered foam/film PVDF nanocomposites with efficient EMI shielding effectiveness and ultralow reflection power were fabricated by physical foaming. The unique layered foam/film structure was composed of PVDF/SiCnw/MXene (Ti3C2Tx) composite foam as absorption layer and highly conductive PVDF/MWCNT/GnPs composite film as a reflection layer. The foam layer with numerous heterogeneous interfaces developed between the SiC nanowires (SiCnw) and 2D MXene nanosheets imparted superior EM wave attenuation capability. Furthermore, the microcellular structure effectively tuned the impedance matching and prolonged the wave propagating path by internal scattering and multiple reflections. Meanwhile, the highly conductive PVDF/MWCNT/GnPs composite (~ 220 S m−1) exhibited superior reflectivity (R) of 0.95. The tailored structure in the layered foam/film PVDF nanocomposite exhibited an EMI SE of 32.6 dB and a low reflection bandwidth of 4 GHz (R < 0.1) over the Ku-band (12.4 − 18.0 GHz) at a thickness of 1.95 mm. A peak SER of 3.1 × 10–4 dB was obtained which corresponds to only 0.0022% reflection efficiency. In consequence, this study introduces a feasible approach to develop lightweight, high-efficiency EMI shielding materials with ultralow reflection for emerging applications.

scholarly journals Effect of Textile-Substrate Pore Size on Electromagnetic Interference Shielding Performance of Conductive Nanocomposite Coated Fabrics

2021 ◽  
Author(s):  
Yijie Hou ◽  
Min Guo ◽  
Xiangpeng Li ◽  
Minghan Duan ◽  
Yongtang Jia ◽  
...  
Keyword(s):  
Pore Size ◽  
Electromagnetic Interference ◽  
High Efficiency ◽  
Great Promise ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
Fabric Density ◽  
Fabric Structure ◽  
Coated Fabrics

Abstract Textile-substrate electromagnetic interference (EMI) shielding materials show great promise for next-generation electronic communication technology challenges. However, new strategies based on structure optimization are desired for improving EMI shielding performance. Here, we demonstrate the controlling effect of fabric structure on the shielding effectiveness of the EMI fabrics. Plain fabrics with different fabric densities were weaved and used as the substrate to be layer-by-layer assembled by graphite oxide (GO) and polypyrrole (PPy). The conductive GO/PPy nanocomposite coating endows commercial cotton fabrics with an EMI shielding ability. In comparison, the EMI shielding effectiveness of the GO/PPy fabrics is depended on the fabric density, that is, the pore size. The EMI shielding effectiveness of the 100 × 100 picks/ 10cm coated fabric was 19.2 dB in 3.9−6.0 GHz frequency range, which is increased by about 71% through the control of the textile-substrate pore size. Interestingly, the EMI shielding effectiveness always peaks at the fabric density of 100 × 100 picks/ 10cm, different from the electrical conductivity. Moreover, the sueding treatment can further improve the EMI shielding effectiveness of the GO/PPy coated fabrics. It is because that the creation of plush increases the multi-reflection of electromagnetic waves in the fabric. This work presents the significance of fabric structure to EMI shielding performance, offering new opportunities for the development of high efficiency EMI shielding fabrics.

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.

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.

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.

scholarly journals Electromagnetic Interference Shield of Highly Thermal-Conducting, Light-Weight, and Flexible Electrospun Nylon 66 Nanofiber-Silver Multi-Layer Film

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1805
Author(s):  
Jaeyeon Kim ◽  
Suyeong Lee ◽  
Changho Kim ◽  
Yeongcheol Park ◽  
Mi-Hyun Kim ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electromagnetic Interference ◽  
Fabrication Process ◽  
Light Weight ◽  
Shielding Effectiveness ◽  
Multiple Reflections ◽  
Scanning Calorimetry ◽  
Silver Films ◽  
Nylon 66 ◽  
Emi Shielding Effectiveness

A light-weight, flexible electromagnetic interference (EMI) shield was prepared by creating a layer-structured metal-polymer composite film consisting of electrospun nylon 66 nanofibers with silver films. The EMI shielding effectiveness (SE), specific SE, and absolute SE of the composite were as high as 60.6 dB, 67.9 dB cm3/g, and 6792 dB cm2/g in the X- and Ku-bands, respectively. Numerical and analytical calculations suggest that the energy of EM waves is predominantly absorbed by inter-layer multiple reflections. Because the absorbed EM energy is dissipated as heat, the thermal conductivity of absorption-dominant EMI shields is highly significant. Measured thermal conductivity of the composite was found to be 4.17 Wm−1K−1 at room temperature, which is higher than that of bulk nylon 66 by a factor of 16.7. The morphology and crystallinity of the composite were examined using scanning electron microscopy and differential scanning calorimetry, respectively. The enhancement of thermal conductivity was attributed to an increase in crystallinity of the nanofibers, which occurred during the electrospinning and subsequent hot pressing, and to the high thermal conductivity of the deposited silver films. The contribution of each fabrication process to the increase in thermal conductivity was investigated by measuring the thermal conductivity values after each fabrication process.

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