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Journal ArticleDOI

Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

17 Sep 2015-Applied Physics Letters (AIP Publishing)-Vol. 107, Iss: 11, pp 113107
TL;DR: In this article, the authors reported Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/polyvinylidene difluoride (PVDF).
Abstract: We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors reported the preparation of nanocomposites of reduced graphene oxide with embedded Fe3O4/Fe nanorings (FeNR@rGO) by chemical hydrothermal growth.
Abstract: We report the preparation of nanocomposites of reduced graphene oxide with embedded Fe3O4/Fe nanorings (FeNR@rGO) by chemical hydrothermal growth. We illustrate the use of these nanocomposites as novel electromagnetic wave absorbing materials. The electromagnetic wave absorption properties of the nanocomposites with different compositions were investigated. The preparation procedure and nanocomposite composition were optimized to achieve the best electromagnetic wave absorption properties. Nanocomposites with a GO:α-Fe2O3 mass ratio of 1:1 prepared by annealing in H2/Ar for 3 h exhibited the best properties. This nanocomposite sample (thickness = 4.0 mm) showed a minimum reflectivity of–23.09 dB at 9.16 GHz. The band range was 7.4–11.3 GHz when the reflectivity was less than–10 dB and the spectrum width was up to 3.9 GHz. These figures of merit are typically of the same order of magnitude when compared to the values shown by traditional ferric oxide materials. However, FeNR@rGO can be readily applied as a microwave absorbing material because the production method we propose is highly compatible with mass production standards.

152 citations

Journal ArticleDOI
TL;DR: In this paper, seven categories of materials and their applications in a microwave regime are elaborately discussed, including magnetic materials, carbon-based materials, flexible or stretchable materials, biomaterials, phantoms, tunable materials and metamaterials.
Abstract: The performance of microwave devices mainly depends on the properties of materials used in the fabrication. Knowledge of material properties at microwave frequencies is a prerequisite to select suitable materials for various microwave applications and vice versa. In this review, seven categories of materials and their applications in a microwave regime are elaborately discussed. The categories include magnetic materials, carbon-based materials, flexible or stretchable materials, biomaterials, phantoms, tunable materials and metamaterials. A brief overview of other important microwave materials such as low-loss ceramic dielectric materials, low-loss polymer ceramic composites, glass ceramics and multilayer ceramics is also given. The objective of this review is to expose the world of materials for wide microwave applications and thereby properly assisting the material selection for specific applications. Moreover, this review has dual significance. It helps material scientists to develop new materials and modify the properties of the available materials with respect to the application requirements. It also assists microwave engineers to select and use appropriate materials for different microwave applications.

99 citations

Journal ArticleDOI
TL;DR: In addition to EMI shielding capability, this composite material exhibits outstanding heat dissipation ability (72 °C to room temperature in less than 90 s) as well as high heat sustainability.
Abstract: Herein, we report high electromagnetic interference (EMI) shielding effectiveness of −40 dB in the Ku-band (for a 600 μm thick film) through a unique core–shell heterostructure consisting of a ferr...

96 citations

Journal ArticleDOI
TL;DR: In this article, a simple and effective approach, i.e., solid phase extrusion (SPE), was proposed to fabricate segregated carbon nanotube (CNT)/poly(vinylidene fluoride) composites with high mechanical performance.

70 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used a facile impregnation-calcination process to obtain metacomposites with tunable negative permittivity and enhanced shielding effectiveness.
Abstract: The recent rise of metacomposites offered a new research strategy for electromagnetic shielding materials owing to their negative electromagnetic parameters, such as negative permittivity. Herein, we prepared silver/silicon nitride (Ag/Si3N4) metacomposites with tunable negative permittivity by a facile impregnation-calcination process, and explored their electrical conductivity, permittivity and electromagnetic shielding properties. As the Ag content increased, formative metal networks in the composites rendered their conductivity characteristic changing from a hopping conductivity to a metal-like conductivity. Tunable negative permittivity behavior combined with enhanced shielding effectiveness (SE) was observed at 2–18 GHz in the metacomposites with high Ag contents. The plasma-like negative permittivity was accounted for by a low frequency plasmonic state of free electrons in the inductive Ag networks, and the frequency band and absolute magnitude of negative permittivity could be adjusted by controlling Ag content, which was well described by Drude model. The average total SE of our obtained metacomposite could reach ~30 dB, and the reflection was the primary shielding mechanism, which was attributed to the intense impedance mismatching stemmed from the negative permittivity. Our work opens up the possibility of designing metacomposites for promising electromagnetic shielding materials, promoting their application in microwave field.

63 citations

References
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Journal ArticleDOI
01 Mar 2009-Carbon
TL;DR: In this paper, composites based on graphene-based sheets have been fabricated by incorporating solution-processable functionalized graphene into an epoxy matrix, and their electromagnetic interference (EMI) shielding studies were studied.

1,175 citations

Journal ArticleDOI
TL;DR: A facile approach to produce lightweight microcellular polyetherimide (PEI)/graphene nanocomposite foams with a density of about 0.3 g/cm3 is reported by a phase separation process.
Abstract: We report a facile approach to produce lightweight microcellular polyetherimide (PEI)/graphene nanocomposite foams with a density of about 0.3 g/cm3 by a phase separation process. It was observed that the strong extensional flow generated during cell growth induced the enrichment and orientation of graphene on cell walls. This action decreased the electrical conductivity percolation from 0.21 vol % for PEI/graphene nanocomposite to 0.18 vol % for PEI/graphene foam. Furthermore, the foaming process significantly increased the specific electromagnetic interference (EMI) shielding effectiveness from 17 to 44 dB/(g/cm3). In addition, PEI/graphene nanocomposite foams possessed low thermal conductivity of 0.065–0.037 W/m·K even at 200 °C and high Young’s modulus of 180–290 MPa.

659 citations

Journal ArticleDOI
TL;DR: In this article, materials for the electromagnetic interference (EMI) shielding of electronics and radiation sources are reviewed, with emphasis on composite materials and resilient EMI gasket materials, which shield mainly by reflection of the radiation at a high frequency.
Abstract: Materials for the electromagnetic interference (EMI) shielding of electronics and radiation sources are reviewed, with emphasis on composite materials and resilient EMI gasket materials, which shield mainly by reflection of the radiation at a high frequency.

605 citations

Journal ArticleDOI
TL;DR: In this paper, thin and flexible composite films of raw or purified multiwalled carbon nanotube (MWCNT) with various mass fractions and poly(methylmethacrylate) (PMMA) were synthesized for electromagnetic interference (EMI) shielding material.
Abstract: Thin and flexible composite films of raw or purified multiwalled carbon nanotube (MWCNT) with various mass fractions and poly(methylmethacrylate) (PMMA) were synthesized for electromagnetic interference (EMI) shielding material. From scanning electron microscopy and high-resolution transmission electron microscopy photographs, we observed the formation of a conducting network through MWCNTs in an insulating PMMA matrix and the existence of an Fe catalyst in MWCNTs. The dc conductivity (σdc) of the systems increased with increasing MWCNT mass fraction, showing typical percolation behavior. The measured EMI shielding efficiency (SE) of MWCNT–PMMA composites by using the extended ASTM D4935-99 method (50 MHz–13.5 GHz) increased with increasing MWCNT mass fraction as σdc. The highest EMI SE for raw MWCNT–PMMA composites was ∼27 dB, indicating commercial use for far-field EMI shielding. The contribution of absorption to total EMI SE of the systems is larger than that of reflection. Based on magnetic permeabili...

569 citations

Journal ArticleDOI
TL;DR: In this paper, the basic expressions of a plane-wave shielding theory are modified and plotted with universal parameters for convenient use in performance calculations of both solid and perforated sheets.
Abstract: Plane-wave shielding theory is developed and discussed for a number of important cases such as single, double, and laminated shields. For application to design, the basic expressions are modified and plotted with universal parameters for convenient use in performance calculations of both solid and perforated sheets. Performances of solid copper and iron shields have been calculated and are presented in both tabular and graphical form. For these and other materials, measurement results of various experiments are tabulated for a number of different material forms and for various incident-wave impedances. Some consideration is given to shielding discontinuities and trends in modern shielding enclosures. >

542 citations