Graphene is often touted as a new miracle material. Harder than diamond, nearly transparent and the most conductive material known to man [1]. At one atom thick it’s the thinnest material known to man and its possibilities, we are told, are endless. From solar cells, to smart windows, batteries to computer chips, water filters to DNA sequencing, the range of potential applications being researched by companies all over the world is huge. But what does all this mean for the world of composites?

What is Graphene?

Graphene is a sheet of Carbon atoms in a honeycomb structure. It is essentially a single layer of Graphite. When we talk of Graphene however, we mean Graphene and its derivatives [2]. These include Graphite, reduced Graphene oxide, Graphene oxide and Graphite oxide. Each bring their own unique properties.

How is it produced?

Graphene, roll of scotch tape and Graphene transistor exhibit in Nobel museum in Stockholm, donated by Nobel Prize winners Andre Geim and Konstantin Novoselov

When Graphene was discovered in a Manchester University laboratory in 2004, the process used was a simple piece of sticky tape to remove flakes from a solid lump of Graphite. This process is known as mechanical exfoliation [2]. While the process was good enough to win the Nobel prize in Physics, it is not a suitable way of producing industrial quantities of Graphene.

High quality Graphene is these days produced by a process known as chemical vapour deposition, however this is very expensive. This process involves putting an organic, Carbon-based gas in a closed container, with a piece of metal at the bottom and then increasing the temperature and pressure until a layer of Graphene is formed on it. Cheaper methods involve the manufacture of Graphene nanoplatelets or few-layer Graphene using a more sophisticated version of mechanical exfoliation, or liquid exfoliation, where Graphene is produced by sonication.

But Graphene in itself does not mix naturally with other materials. In order to ensure that its wonder properties can be used in different materials, the Graphene needs to be functionalised. This is where a plasma reactor is used to add compatible chemical groups to the surface of Graphene, in order to enable the effective dispersion of Graphene. Depending on how the Graphene is functionalised, it can produce wildly different properties [3].

What are the benefits?

With a tensile strength of 130GPa and modulus of 1050GPa [2], Graphene is currently the strongest material known to man. To gain a sense of how this compares to other materials, we have prepared a table of specific strength and modulus (strength and modulus per unit weight) of different engineering materials below.

But the reported benefits don’t stop at its mechanical properties. It’s conductivity properties are also said to have the potential to be a game changer. With Graphene tin oxide being used as an anode in lithium ion batteries for example, batteries can be made to last much longer between charges (potential capacity has increased by a factor of 10), and with almost no reduction in storage capacity between charges, effectively making technology such as electronically powered vehicles a much more viable transport solution in the future [7]

Another use for Graphene is in paint. Graphene is highly inert and so can act as a corrosion barrier to prevent oxygen and water diffusion. This could mean that future vehicles could be made to be corrosion resistant, as Graphene can be made to be grown onto any metal surface (given the right conditions) [8].

Alternatively, due to its highly conductive properties, it can be used to make printed circuit boards. You could print incredibly small circuitry, without the need for soldering. As we reach the physical limits of how small we can make circuitry by current methods, it is thought that this is one way which we could ensure that Mohr’s law continues, allowing us to see increasingly powerful computers. Excitingly IBM claim that Graphene circuit boards have already been found to perform 10,000 times better than the existing technology [9].

But what does all this mean for composites?

We have already seen how strong Graphene is, but can those properties be transferred into composites? We have already seen some benefits of its use in the matrix of composites. Graphene chemically bonds to both the resin and the fibre, acting like little hooks which increase the interfacial shear strength between the resin and the fibre, giving a 50% increase in the interlaminar shear properties of your composite material. Graphene infused resins are also up to 50% less dense than standard resins, which leads to even lighter composite materials. Higher impact strengths have also been reported. Furthermore and as it is highly conductive, it is believed that we could see more functionalised composites in the future, by imbedding printed circuitry and sensors [3].

Further benefits have also been reported, which will see great interest in different industries. The marine industry will be excited at the reports of improved environmental performance and reduced water uptake in resins containing Graphene [4]. The aerospace industry will keenly embrace the improved lightning strike protection afforded by conductive composites and likewise conductive composites mean a reduced chance of static electricity build up, which can be the death nell of wind turbines [10].

However, many of these reported benefits are currently theoretical and may not transform into real world products. Due to this reason, now may not be the right time to get too carried away by the hype.

Are there examples of graphene infused products on the market today?

Yes, there are a number of products available that report to benefit from the wonder properties of Graphene. The BAC mono is the first production road car to used Graphene infused carbon fibre prepreg to make up its body work. Likewise the Dassi interceptor is the first road bike that benefits from the technology. Dassi believe that they can potentially build bikes as light as 350 grams thanks to Graphene infused carbon fibre.

If you are looking for a more cost accessible entry into the world of Graphene infused products, then Head offer tennis rackets and skis that report to deliver the benefits of Graphene into the world of sports. There are also Graphene enhanced crash helmets, which claim to offer major improvements in impact absorption.

Surely these are just the tip of the ice berg. Over the coming years we are likely to see a plethora of Graphene infused products delivering currently unforeseen benefits. How far will the Graphene revolution take us? Only time will tell.

References

1. 2015. Graphene – What is it?. [ONLINE] Available at: https://www.graphenea.com/pages/graphene#.WsTpfujwaHs. [Accessed 4 April 2018].
2. IRT Saint Exupéry. (2018). Graphene in Composites, unexpected science from a pencil trace by Constantinos Soutis. [Online Video]. 6 September 2017. Available from: https://www.youtube.com/watch?v=HDxv40K6Dk8. [Accessed: 4 April 2018].
3. Global Cycling Network. (2017). The next carbon fibre? why graphene could be the future of bikes. [Online Video]. 22 January 2017. Available from: https://www.youtube.com/watch?v=FaKl3OymFy4. [Accessed: 4 April 2018].
4. 2007. Properties of Steel. [ONLINE] Available at: http://www.matweb.com/Search/MaterialGroupSearch.aspx?GroupID=225. [Accessed 4 April 2018].
5. Performance Composites. 2009. Mechanical Properties of Carbon Fibre Composite Materials, Fibre / Epoxy resin (120°C Cure). [ONLINE] Available at: http://www.performance-composites.com/carbonfibre/mechanicalproperties_2.asp. [Accessed 4 April 2018].
6. 2015. Properties of Graphene. [ONLINE] Available at: https://www.graphenea.com/pages/properties-of-graphene#.WsTiaujwaHs. [Accessed 4 April 2018].
7. 2015. Graphene Supercapacitors – What are they? [ONLINE] Available at: https://www.graphenea.com/pages/graphene-supercapacitors-what-are-they#.WsTwAOjwaHs . [Accessed 4 April 2018].
8. Graphene – Info. 2018. Graphene Paints: introduction and market status. [ONLINE] Available at: https://www.graphene-info.com/graphene-paints. [Accessed 4 April 2018].
9. PCB Train. 2015. WHAT IS GRAPHENE AND WHAT WILL IT BRING TO THE WORLD OF ELECTRONICS?. [ONLINE] Available at: https://www.pcbtrain.co.uk/blog/graphene-will-bring-world-electronics. [Accessed 4 April 2018].
10. Montanyà, Joan, Van der Velde, Oscar and Williams, Earle R. 2014. Lightning discharges produced by wind turbines. Journal of Geophysical Research: Atmospheres, 1455-146
11. 2015. CVD Graphene – Creating Graphene via Chemical Vapur Deposition [ONLINE] Available at: https://www.graphenea.com/pages/cvdgraphene#.WsTvVOjwaHs . [Accessed 4 April 2018].