Pan European Networks - Horizon 2020 - page 78

G
raphene, a layered carbon material, is the subject of
intense global research to exploit the observed ‘wonder
material’ properties. Experimental characterisation has
revealed that graphene is mechanically 200 times stronger than
steel, highly flexible, has in-plane electrical conductivity higher than
copper, has thermal conductivity comparable to diamond, is gas
impermeable, and has an incredible surface area of over 2,500m
2
per gram. Haydale offers an enabling technology which has the
potential to realise these properties in engineering challenges.
Graphene nanoplatelets (GNP), the particulate form of graphene,
are now widely produced, being manufactured either ‘top down’
from mined graphite or ‘bottom-up’ by chemical processing from
a carbon precursor. Haydale, a UK-based SME, proposes that the
key requirement for realising graphene’s potential, when added to
a material system such as a polymer, lies in tailoring the surface
chemistry, which influences dispersion and interaction with a
host matrix. Surface chemistry can be altered by aggressive
chemical treatments, but these add impurities and damage the
graphene surface.
The Haydale alternative is a patent pending, environmentally
‘clean’ chemical functionalisation process. The HDPlas® plasma
treatment operates at low temperature (under 100°C) and allows
a wide range of chemical groups such as O
2
, COOH, NH
3
and F to
be attached to the surface of GNPs without imparting any
additional impurities. Compared to acid-based processes,
functionalisation via plasma is a clean, low energy process which
avoids generating hazardous waste chemicals, with the capability
to realise the full effects of graphene in a financially and
environmentally viable way. The process has been independently
verified by the UK National Physical Laboratory.
Haydale, listed on the London Stock Exchange (AIM) in April 2014,
has a manufacturing site near Swansea, South Wales, and a
composites development facility in Loughborough, England. Led by
CEO Ray Gibbs, it sources GNPs and other particulate materials,
such as carbon nanotubes (CNT), from a variety of sources and
applies a chemical surface modification to assist nanomaterials
processing.
Applications
The list of potential uses of graphene to exploit one or more of the
exceptional properties includes additions to inks, coatings,
thermoplastic and thermoset polymers, membranes, electrodes
and sensors. Haydale is working in a number of industrial sectors,
for example inks and coatings for flexible and printed electronics;
3D printing of electrically conductive materials; printing of sensors
– both biomedical and pressure; electromagnetic shielding and
radio-frequency identification; electrochemical for photovoltaics,
batteries and supercapacitors; anti-corrosion coatings; chemical
barriers; and heat-resistant polymers and heat diffusion.
Composites
Polymer composites are a class of materials finding increasing
use in applications across transport, aerospace, automotive,
ballistics, sport, infrastructure, energy and medical markets.
Haydale has signalled its intent to work in this market by the
acquisition of EPL Composite Solutions (rebranded as Haydale
Composite Solutions), which specialises in the design,
development and commercialisation of advanced polymer
composite materials and structures. Its customers include
significant corporations such as National Grid, SSE, EirGrid,
Chevron, Anglian Water, Severn Trent Water, Yorkshire Water and
3M. Haydale is therefore strongly positioned to exploit the market
applications for graphene-enhanced composites.
Recent research has shown promising results.The mechanical
performance of epoxy resin has been shown to be significantly
enhanced by the addition of HDPlas functionalised GNPs. In
research reported in 2014 by the Aerospace Corporation, USA, the
addition of Haydale functionalised graphene to epoxy resin resulted
in a significant influence on mechanical performance, increasing
tensile strength and doubling modulus with retained toughness.
Aerospace
As well as improved specific strength and stiffness, the aerospace
industry tends to limit design of composite structures based upon
the compression after impact properties (that is, the remaining
strength of a composite after it has been damaged).Work
reported in 2014 by the Cardiff School of Engineering under the
EU Clean Sky Joint Technology Initiative showed that incorporating
Haydale functionalised GNP and CNT into carbon-reinforced
composites resulted in a 50% increase in compression after
impact strength. In-plane shear strength was also improved by up
to 60%, highlighting the strengthening and toughening attributes
of the Haydale functionalised carbon nanomaterials.
Non-structural attributes of graphene are also being investigated
in research projects between Haydale, manufacturers of carbon-
reinforced pre-pregs and aircraft manufacturers. Research is
currently being undertaken to replace sacrificial metal mesh
which is used as a lightning strike protector (one of the biggest
threats to aircraft safety when airborne) in composite wings and
The Haydale plasma process for surface functionalisation of particulate materials is
opening up the commercial benefits of graphene in applications such as composites
Plasma-enhanced
graphene composites
78
I S S U E S I X
H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L
P R O F I L E
G R A P H E N E R E S E A R C H
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