In situ reduction of graphite oxide in polymer powder has been implemented using focused solar electromagnetic radiation. The simultaneous reduction of graphite oxide, melting of the polymer and embedding of reduced graphite oxide nanoflakes in polymer offer a new way of synthesizing conducting graphene/polymer composites. An electromechanical application of the present reduced graphite oxide-PVDF nanocomposite has been proposed with a gauge factor of 12.1. © 2012 The Royal Society of Chemistry.

Krishnan Balasubramaniam

Department of Mechanical Engineering

Sundara Ramaprabhu

Department Of Physics

Gauge factors

GRAPHITE OXIDE

In-situ

Nanoflakes

One-pot synthesis

POLYMER POWDERS

Simultaneous reduction

SOLAR ELECTROMAGNETIC RADIATION

STRAIN SENSING

Graphene

Graphite

Polymers

Carbon nanotube

oxide

polymer

POLYVINYL DERIVATIVE

polyvinylidene fluoride

article

chemistry

synthesis

ultrastructure

Nanotubes, Carbon

Oxides

POLYVINYLS

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Nanoscale

Graphene-polymer nanocomposite films show good piezoresistive behaviour and it is reported that the sensitivity increases either with the increased sheet resistance or decreased number density of the graphene fillers. A little is known about this behaviour near the percolation region. In this study, graphene nanoplatelet (GNP)/poly (methyl methacrylate) (PMMA) flexible films are fabricated via solution casting process at varying weight percent of GNP. Electrical and piezoresistive behaviour of these films is studied as a function of GNP concentration. Piezoresistive strain sensitivity of the films is measured by affixing the film to an aluminium specimen which is subjected to monotonic uniaxial tensile load. The change in resistance of the film with strain is monitored using a four probe. An electrical percolation threshold at 3 weight percent of GNP is observed. We report non-monotonic piezoresistive behaviour of these films as a function GNP concentration. We observe an increase in gauge factor (GF) with unstrained resistance of the films up to a critical resistance corresponding to percolation threshold. Beyond this limit the GF decreases with unstrained resistance. © BME-PT.

Express Polymer Letters

Non-monotonic piezoresistive behaviour of graphene nanoplatelet (GNP)-polymer composite flexible films prepared by solvent casting

Herein we report a rapid, chemical free and low temperature method for high throughput production of graphene by exfoliation of graphite oxide using focused solar radiation. The simple method of preparation, easy scalability, cost effectiveness and high electrical conductivity (1.5 × 103 S m-1) of solar graphene hold great promise for true practical applications. © 2011 The Royal Society of Chemistry.

Journal of Materials Chemistry

Top down method for synthesis of highly conducting graphene by exfoliation of graphite oxide using focused solar radiation

Novel foam composites comprising functionalized graphene (f-G) and polyvinylidene fluoride (PVDF) were prepared and electrical conductivity and electromagnetic interference (EMI) shielding efficiency of the composites with different mass fractions of f-G have been investigated. The electrical conductivity increases with the increase in concentration of f-G in insulating PVDF matrix. A dramatic change in the conductivity is observed from 10 -16 S · m-1 for insulating PVDF to 10-4 S · m-1 for 0.5 wt.% f-G reinforced PVDF composite, which can be attributed to high-aspect-ratio and highly conducting nature of f-G nanofiller, which forms a conductive network in the polymer. An EMI shielding effectiveness of ≈20 dB is obtained in X-band (8-12 GHz) region and 18 dB in broadband (1-8 GHz) region for 5 wt.% of f-G in foam composite. The application of conductive graphene foam composites as lightweight EMI shielding materials for X-band and broadband shielding has been demonstrated and the mechanism of EMI shielding in f-G/PVDF foam composites has been discussed. © 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Macromolecular Materials and Engineering

Functionalized graphene-PVDF foam composites for EMI shielding

Novel polymer nanocomposites comprising of MnO2 nanotubes (MNTs), functionalized multiwalled carbon nanotubes (f-MWCNTs), and polyvinylidene fluoride (PVDF) were synthesized. Homogeneous distribution of f- MWCNTs and MNTs in PVDF matrix were confirmed by field emission scanning electron microscopy. Electrical conductivity measurements were performed on these polymer composites using four probe technique. The addition of 2 wt.% of MNTs (2 wt.%, f-MWCNTs) to PVDF matrix results in an increase in the electrical conductivity from 10-16S/m to 4.5 × 10-5S/m (3.2 × 10-1S/m). Electromagnetic interference shielding effectiveness (EMI SE) was measured with vector network analyzer using waveguide sample holder in X-band frequency range. EMI SE of approximately 20 dB has been obtained with the addition of 5 wt.% MNTs-1 wt.% f-MWCNTs to PVDF in comparison with EMI SE of approximately 18 dB for 7 wt.% of f-MWCNTs indicating the potential use of the present MNT/f-MWCNT/PVDF composite as low-cost EMI shielding materials in X-band region. © 2011 Eswaraiah et al.

Nanoscale Research Letters

Inorganic nanotubes reinforced polyvinylidene fluoride composites as low-cost electromagnetic interference shielding materials

Functionalized graphene-polyvinylidene fluoride (f-G-PVDF) nanocomposite films were synthesized using a simple solvent casting technique. The investigation demonstrates the real time strain response of f-G-PVDF nanocomposites on the macro-scale under tensile loads and the use of this nanocomposite as strain sensor. This is ascribed to the variation of electrical properties of graphene-polymer upon mechanical deformation at the nanoscale. © 2011 The Royal Society of Chemistry.

Functionalized graphene reinforced thermoplastic nanocomposites as strain sensors in structural health monitoring

Carbon

Hydrazine-reduction of graphite- and graphene oxide

One-pot synthesis of conducting graphene-polymer composites and their strain sensing application

Journal	Nanoscale
ISSN	20403364
Open Access	No