PROFILE GRAPHENE RESEARCH Plasma-enhanced graphene composites the Haydale plasma process for surface functionalisation of particulate materials is opening up the commercial benefits of graphene in applications such as composites 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 2,500m2 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 O2, COOH, NH3 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; 78 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 carbonreinforced 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 ★ 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 www.horizon2020projects.com PROFILE GRAPHENE RESEARCH Photo credit: Mark Lloyd fuselage with a new range of functionalised graphene composites that utilise the increased electrical conductivity to improve lightning strike protection. Sport The sports industry is continually seeking enhanced performance for competitive advantage. In competitive race sailing, Haydale has signed heads of terms for a collaboration agreement with Alex Thomson Racing, the HUGO BOSS sponsored extreme sailing team. The aim is to incorporate graphene-enhanced materials in their research and development programme to improve overall strength and stiffness for a number of key structures within their boat so as to keep their vessel light to ensure optimum speed without compromising on strength. Automotive The automotive industry uses composite materials primarily for their light weight, to reduce part count and complexity, and to manufacture complex shapes. The target benefits are lower manufacturing costs, as well as reduction in fuel consumption, leading to lower emissions in service. An example of work underway is in an EU-funded programme to make highperformance graphene composites that could reduce the weight of car structures by one-third or more. Summary Haydale has a materials technology which is proven to enhance the processing of graphene and nanomaterials in order to realise the exciting potential of these new materials. Key benefits of the Haydale HDPlas plasma functionalisation process are: n Wide range of chemical groups and levels of functionalisation achievable; n n n n No damage to the surface or additional impurities added; Low environmental impact – no hazardous waste stream, low temperature, low energy process; Applicable to a wide range of particulate materials; and Treated materials have enhanced dispersion and chemical bonding to a matrix. We are seeking partners from industry, research organisations and academia to develop collaborative research programmes in European and other funding schemes. Haydale is seeking to develop new products and to work with the whole supply chain – graphene producers, intermediate materials processors and end users across the EU and globally. Together with our existing and future partners we look forward to seeing the full potential of graphene across a diverse range of commercial applications. Ray Gibbs CEO Haydale Ltd tel: +44 (0)1269 842946 [email protected] www.haydale.com Reproduced by kind permission of Pan European Networks Ltd, www.paneuropeannetworks.com © Pan European Networks 2015 www.horizon2020projects.com H O R I z O N 2 0 2 0 P R O j E C t S : P O R t A L ★ I S S U E S I X ★ 79