Graphene nanoribbon–PVA composite as EMI shielding material in the X band

Abstract

A very thin graphene nanoribbon/polyvinyl alcohol (GNR/PVA) composite film has been developed which is light weight and requires a very low concentration of filler to achieve electromagnetic interference (EMI) shielding as high as 60 dB in the X band. Atomic force microscope studies show very well conjugated filler concentration in the PVA matrix for varying concentrations of GNR supported by Raman spectroscopy data. The films show 14 orders of increase in conductivity with a GNR concentration of 0.75% [corrected] in PVA. This is possible because of the interconnected GNR network providing a very low percolation threshold as observed from the electrical measurements. Local density of states study of GNR using scanning tunnelling spectroscopy shows the presence of localized states near the Fermi energy. There are multiple advantages of GNR as an EMI shielding material in a polymer matrix. It has good dispersion in water, the conductive network in the composite shows very high electrical conductivity for a very low concentration of GNR and the presence of localized density of states near Fermi energy provides the spin states required for the absorbance of radiation energy in the X band.

Carbon nanostructure composite for electromagnetic interference shielding

“…Therefore, high conductivity, high permeability and sufficient thickness are the perquisites to achieve the required skin depth [10][11][12]. However, high conductivity is not the only criterion for shielding.…”

“…Therefore, the researchers are trying to develop a state-of-the-art and commercially viable nanocomposite which will have all such characteristics to fulfill EMI shielding attributes. EMI shielding of a composite shielding material depends mainly on the aspect ratio, filler's intrinsic conductivity, dielectric constant, magnetic properties and physical geometry [8,11]. According to the EM wave percolation theory, electrical conductivity of the composite is determined by its ease in forming the conductive network [8,12].…”

“…Generally, polymer composites have conductive fillers such as metal nanoparticles, magnetic nanoparticles, carbon-based materials (graphene oxide, CNT, graphene, carbon black, graphite and graphene nanoribbon), fibres, foams, and so on [8,[14][15][16][17]. The EMI shielding of a composite shielding material depends mainly on the aspect ratio of fillers, filler's intrinsic conductivity, dielectric constant, magnetic properties and physical geometry [8,11]. According to the EM wave percolation theory, electrical conductivity of the composite is determined by its ease in forming the conductive network [8,12].…”

Graphene/Polymer Nanocomposites as Microwave Absorbers

“…These characteristics make PVA an attractive matrix material to host graphene-related fillers. In a recent work [26], very thin (0.3-0.6 mm) graphene nanoribbon/polyvinyl alcohol (GNR/PVA) composite films with different amounts of GNR particles have been developed for shielding EM waves in the X-band. GNR particles were obtained by unzipping multiwall carbon nanotubes [27].…”

Synergistic Conductivity and Electromagnetic Interference Shielding Effectiveness of Epoxy/Carbon Fiber and Epoxy/Carbon Black Composites via Mixing with Bamboo Charcoal

“…Valentini et al (2015) have presented that the commercial thermoplastic polyurethane filled with exfoliated graphite (EG) composites had a EMI shielding effectiveness of -20 dB with 20 wt.% EG in the frequency of 8.2 to 2.3 GHz. Joshi et al (2013) reported a kind of thin film of graphene nanoribbon-polyvinyl alcohol composite with a high EMI shielding of 60 dB. Thomassin et al (2013) showed different strategies of preparing EMI shielding composites, and the results on EMI shielding effectiveness with various fillers used in the study was ranked as: carbon black < carbon fiber < carbon nanotube < graphene sheet.…”