Flexible few-layered graphene/poly vinyl alcohol composite sheets: synthesis, characterization and EMI shielding in X-band through the absorption mechanism

Marka, Sandeep Kumar; Sindam, Bashaiah; Raju, K. C. James; Srikanth, Vadali V. S. S.

doi:10.1039/c5ra04038h

Cited by 56 publications

(28 citation statements)

References 46 publications

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“…In all of the composites, PVA and G@MgO crystallized in monoclinic and hexagonal crystal systems, respectively. The process of hot pressing has enhanced the crystallization of PVA as evidenced from the appearance of new diffraction peaks (unlike in our previous report) in all the composite samples. The (101̅) diffraction peak is the major intense peak in monoclinic PVA .…”

Section: Resultscontrasting

confidence: 59%

“…It is observed that (as shown in Figure a) in the 0.6- and 1.0G@MgO/PVA_Coag composites the (101) diffraction peak is developed at the expense of the (101̅) diffraction peak intensity. It is also observed that the addition of G@MgO creates compressive stresses in the PVA matrix and these stresses help PVA crystals to grow …”

Section: Resultsmentioning

confidence: 99%

“…The incident power ( P i ) on a shielding material is divided into reflected power ( P r ), absorbed power and transmitted power ( P t ) at the output of the shielding. The EMI SE of material is defined as SE total = −10 log( P t / P i ) . When electromagnetic radiation is incident on a shielding material, the sum of absorption coefficient ( A ), reflection coefficient ( R ), and transmission coefficient ( T ) must be equal to 1.…”

Section: Experimental Proceduresmentioning

confidence: 99%

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Graphene-Wrapped MgO/Poly(vinyl alcohol) Composite Sheets: Dielectric and Electromagnetic Interference Shielding Properties at Elevated Temperatures

Marka

Srikanth

Sindam

et al. 2019

ACS Appl. Mater. Interfaces

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Different amounts of graphene-wrapped magnesium oxide (G@MgO) powders are uniformly dispersed in poly(vinyl alcohol) (PVA) solution in different experiments to obtain solutions which are coagulated to obtain solid materials, which are then hot pressed at 413 K and 3 t of pressure to finally obtain 1 mm thick freestanding G@MgO/PVA composite sheets in which the constituents, namely, graphene and MgO (in the form of G@MgO), are the nanofillers in PVA matrix. During synthesis of G@MgO powder, MgO nanoparticles are in situ wrapped by the graphene nanosheets as revealed by electron microscopy. Uniformity of G@MgO dispersion in PVA was confirmed by secondary electron micrographs and the consistency in X-ray diffraction and Raman scattering data collected from different locations of the samples. Temperature (303–393 K) dependent complex permittivity of G@MgO/PVA composite sheets (including those prepared by casting) in low frequency (20 Hz to 2 MHz) and high frequency (i.e., X-band, 8.2–12.4 GHz) ranges are measured. In both frequency ranges, G@MgO/PVA composite sheets prepared by coagulation exhibited dielectric properties superior to those of PVA and G@MgO/PVA composite sheets prepared by casting. A strong interfacial polarization is observed in coagulated and as-cast G@MgO/PVA composite sheets. It is noticed from the calculated activation energies that conduction is the dominating mechanism for energy transfer in both composite sheets’ cases, while it is predominating in coagulated composite sheets due to the better network formation of the fillers in the coagulated samples than in the cast composite samples. The electromagnetic interference shielding effectiveness (EMI SE) values in the X-band frequency range (i.e., 8.2–12.4 GHz) of the G@MgO/PVA composite sheets prepared by coagulation are more than those prepared by casting for a particular weight fraction of G@MgO. At 393 K, for a particular G@MgO/PVA composite sheet prepared by coagulation, an excellent EMI SE of ∼27.5 dB is measured. It is also experimentally elucidated that the absorption is the dominating mechanism for EMI SE in the prepared composite sheets.

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Section: Resultscontrasting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Proceduresmentioning

confidence: 99%

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Graphene-Wrapped MgO/Poly(vinyl alcohol) Composite Sheets: Dielectric and Electromagnetic Interference Shielding Properties at Elevated Temperatures

Marka

Srikanth

Sindam

et al. 2019

ACS Appl. Mater. Interfaces

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“…Despite a number of studies reporting on GO and rGO additives, the use of FLG/multi-layer graphene (MLG) for the same purpose is rare [ 16 , 17 ]. This is probably due to the lack of FLG that would fulfil the requirement of efficient and simple synthesis with a relatively high aspect ratio of the product.…”

Section: Introductionmentioning

confidence: 99%

Polyvinyl Alcohol-Few Layer Graphene Composite Films Prepared from Aqueous Colloids. Investigations of Mechanical, Conductive and Gas Barrier Properties

et al. 2020

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Quasi all water soluble composites use graphene oxide (GO) or reduced graphene oxide (rGO) as graphene based additives despite the long and harsh conditions required for their preparation. Herein, polyvinyl alcohol (PVA) films containing few layer graphene (FLG) are prepared by the co-mixing of aqueous colloids and casting, where the FLG colloid is first obtained via an efficient, rapid, simple, and bio-compatible exfoliation method providing access to relatively large FLG flakes. The enhanced mechanical, electrical conductivity, and O2 barrier properties of the films are investigated and discussed together with the structure of the films. In four different series of the composites, the best Young’s modulus is measured for the films containing around 1% of FLG. The most significant enhancement is obtained for the series with the largest FLG sheets contrary to the elongation at break which is well improved for the series with the lowest FLG sheets. Relatively high one-side electrical conductivity and low percolation threshold are achieved when compared to GO/rGO composites (almost 10−3 S/cm for 3% of FLG and transport at 0.5% FLG), while the conductivity is affected by the formation of a macroscopic branched FLG network. The composites demonstrate a reduction of O2 transmission rate up to 60%.

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“…Outros picos detectados em torno de 26º e 27º são relatados na literatura como (130) e (040) respectivamente[104]. Em torno de 2θ = 20º, pôde-se perceber um pico de difração atribuído aos cristais de forma β[104].O difratograma do PVA apresentou um pico mais intenso em 2θ = 19º que é referente ao plano cristalino (101)[105]. O padrão de difração das blendas se mostraram muito similares ao padrão de difração do PHB puro, de modo que os mesmos picos foram observados.…”

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Estudo da miscibilidade de blendas de poli(hidroxibutirato)/poli(álcool vinílico) obtidas por mistura mecânica

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Flexible few-layered graphene/poly vinyl alcohol composite sheets: synthesis, characterization and EMI shielding in X-band through the absorption mechanism

Abstract: An excellent electromagnetic interference shielding effectiveness of ∼19.5 dB was measured for a 1 mm thick flexible few-layered graphene (FLG)/PVA composite sheet owing to the formation of network-like features by FLG in the PVA matrix.

Cited by 56 publications

References 46 publications

Graphene-Wrapped MgO/Poly(vinyl alcohol) Composite Sheets: Dielectric and Electromagnetic Interference Shielding Properties at Elevated Temperatures

Graphene-Wrapped MgO/Poly(vinyl alcohol) Composite Sheets: Dielectric and Electromagnetic Interference Shielding Properties at Elevated Temperatures

Polyvinyl Alcohol-Few Layer Graphene Composite Films Prepared from Aqueous Colloids. Investigations of Mechanical, Conductive and Gas Barrier Properties

Estudo da miscibilidade de blendas de poli(hidroxibutirato)/poli(álcool vinílico) obtidas por mistura mecânica

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