scholarly journals An anisotropic layer-by-layer carbon nanotube/boron nitride/rubber composite and its application in electromagnetic shielding

Nanoscale ◽  
2020 ◽  
Vol 12 (14) ◽  
pp. 7782-7791 ◽  
Author(s):  
Yanhu Zhan ◽  
Emanuele Lago ◽  
Chiara Santillo ◽  
Antonio Esaú Del Río Castillo ◽  
Shuai Hao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Boron Nitride ◽  
Layer By Layer ◽  
Shielding Effectiveness ◽  
Anisotropic Layer ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
Rubber Composite

A carbon nanotube/boron nitride/rubber composite with anisotropic electrical conductivity exhibits an EMI shielding effectiveness of 22.41 dB mm−1 and a thermal conductivity equal to 0.25 W m−1 K−1.

Dual percolations of electrical conductivity and electromagnetic interference shielding in progressively agglomerated CNT/polymer nanocomposites

2021 ◽  
pp. 108128652110214
Author(s):  
Xiaodong Xia ◽  
George J. Weng
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Polymer Nanocomposites ◽  
Electromagnetic Interference ◽  
Effective Medium Theory ◽  
Scale Model ◽  
Shielding Effectiveness ◽  
Emi Shielding

Recent experiments have revealed two distinct percolation phenomena in carbon nanotube (CNT)/polymer nanocomposites: one is associated with the electrical conductivity and the other is with the electromagnetic interference (EMI) shielding. At present, however, no theories seem to exist that can simultaneously predict their percolation thresholds and the associated conductivity and EMI curves. In this work, we present an effective-medium theory with electrical and magnetic interface effects to calculate the overall conductivity of a generally agglomerated nanocomposite and invoke a solution to Maxwell’s equations to calculate the EMI shielding effectiveness. In this process, two complex quantities, the complex electrical conductivity and complex magnetic permeability, are adopted as the homogenization parameters, and a two-scale model with CNT-rich and CNT-poor regions is utilized to depict the progressive formation of CNT agglomeration. We demonstrated that there is indeed a clear existence of two separate percolative behaviors and showed that, consistent with the experimental data of poly-L-lactic acid (PLLA)/multi-walled carbon nanotube (MWCNT) nanocomposites, the electrical percolation threshold is lower than the EMI shielding percolation threshold. The predicted conductivity and EMI shielding curves are also in close agreement with experimental data. We further disclosed that the percolative behavior of EMI shielding in the overall CNT/polymer nanocomposite can be illustrated by the establishment of connective filler networks in the CNT-poor region. It is believed that the present research can provide directions for the design of CNT/polymer nanocomposites in the EMI shielding components.

Largely enhanced electrical properties of polymer composites via the combined effect of volume exclusion and synergy

RSC Advances ◽  
2016 ◽  
Vol 6 (57) ◽  
pp. 51900-51907 ◽  
Author(s):  
Kai Wu ◽  
Linyu Wu ◽  
Weixing Yang ◽  
Songgang Chai ◽  
Feng Chen ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Synergistic Effect ◽  
Core Shell ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
The Core ◽  
Emi Shielding Effectiveness ◽  
Core Shell Structure ◽  
Exclusion Effect

The core–shell structure of surface conductive SiO2@rGO could result in enhanced electrical conductivity and EMI shielding effectiveness as due to both synergistic effect and volume exclusion effect.

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

Materials ◽  
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.

scholarly journals Electrical Properties and Electromagnetic Interference Shielding Effectiveness of Interlayered Systems Composed by Carbon Nanotube Filled Carbon Nanofiber Mats and Polymer Composites

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 238 ◽  
Author(s):  
Claudia Angélica Ramírez-Herrera ◽  
Homero Gonzalez ◽  
Felipe de la Torre ◽  
Laura Benitez ◽  
José Gerardo Cabañas-Moreno ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Electromagnetic Interference ◽  
Communication Systems ◽  
Carbon Nanofiber ◽  
Layered Composite ◽  
Multiwall Carbon Nanotube ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Nanofiber Composite

The demand for multifunctional requirements in aerospace, military, automobile, sports, and energy applications has encouraged the investigation of new composite materials. This study focuses on the development of multiwall carbon nanotube (MWCNT) filled polypropylene composites and carbon nanofiber composite mats. The developed systems were then used to prepare interlayered composites that exhibited improved electrical conductivity and electromagnetic interference (EMI) shielding efficiency. MWCNT-carbon nanofiber composite mats were developed by centrifugally spinning mixtures of MWCNT suspended in aqueous poly(vinyl alcohol) solutions. The developed nanofibers were then dehydrated under sulfuric acid vapors and then heat treated. Interlayered samples were fabricated using a nanoreinforced polypropylene composite as a matrix and then filled with carbon fiber composite mats. The in-plane and through-plane electrical conductivity of an eight-layered flexible carbon composite (0.65 mm thick) were shown to be 6.1 and 3.0 × 10−2 S·cm−1, respectively. The EMI shielding effectiveness at 900 MHz increased from 17 dB for the one-layered composite to 52 dB for the eight-layered composite. It was found that the reflection of the electromagnetic waves was the dominating mechanism for EMI shielding in the developed materials. This study opens up new opportunities for the fabrication of novel lightweight materials that are to be used in communication systems.

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.

Carbon foams with low thermal conductivity and high EMI shielding effectiveness from sawdust

2020 ◽  
Vol 145 ◽  
pp. 112076 ◽  
Author(s):  
A. Chithra ◽  
Praveen Wilson ◽  
Sujith Vijayan ◽  
R. Rajeev ◽  
K. Prabhakaran
Keyword(s):  
Thermal Conductivity ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Low Thermal Conductivity ◽  
Emi Shielding Effectiveness ◽  
Carbon Foams

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

NANO ◽  
2019 ◽  
Vol 14 (06) ◽  
pp. 1950075 ◽  
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.

scholarly journals Ultrathin flexible graphene films with high thermal conductivity and excellent EMI shielding performance using large-sized graphene oxide flakes

RSC Advances ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 1419-1427 ◽  
Author(s):  
Shaofeng Lin ◽  
Su Ju ◽  
Jianwei Zhang ◽  
Gang Shi ◽  
Yonglyu He ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Electromagnetic Interference ◽  
Electronic Devices ◽  
High Thermal Conductivity ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
Graphene Films ◽  
Thermal Conducting

As the demand for wearable and foldable electronic devices increases rapidly, ultrathin and flexible thermal conducting films with exceptional electromagnetic interference (EMI) shielding effectiveness (SE) are greatly needed.

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