Graphene has long been heralded as a ‘wonder material’.
At just one atom in thickness, it is the thinnest material known. It is 200-times stronger than steel and demonstrates an electrical conductivity one million times that of copper. Moreover, graphene has shown significant promise as a means to enhance the mechanical, thermal, electrical and physical properties of elastomers and composites. The addition of just small amounts of graphene products to these materials can increase their strength by over 30%.
However, the widescale use of graphene for such applications has been hampered by expensive and inefficient methods for its production, and a lack of industry standards that meant that early adopters of the nanomaterial were getting inconsistent results.
All of that has now changed.
Graphene suppliers are now achieving excellent and consistent results by producing graphene via the electrochemical exfoliation of graphite. The process is efficient, yields powders containing pristine, high-aspect-ratio platelets of graphene, and can produce tonnage-scale quantities of the material at a price that is attractive to industry. We already have an annual production capacity of 100 tonnes and are planning to scale this even further in the coming years.
Now graphene suppliers must work in close partnership with their customers to prove the benefits and value of graphene products produced using this process in real-world applications.
Graphene in Elastomers
In June 2018, we started working with newGen Group to increase the strength and abrasion-resistance of polymer wear liners using our PureGRAPH® 20-µm graphene nanoplatelets. The global mining industry produces 17 billion metric tonnes of minerals each year, with the iron ore industry alone processing in excess of 1.6 billion tonnes annually. Inevitably, the equipment that handles this ore suffers from wear. The industry uses a range of strategies to prevent this wear and prolong the working life of its equipment. One such strategy is the use of sacrificial wear liners for the protection of steel equipment.
Powders were mixed into the polyurethane (PU) elastomer employed to produce these liners using standard industrial mixing equipment. No pre-treatment of the graphene additive or other formulation changes were required. Liners cast from these enhanced PU resins demonstrated an increase in tensile strength of 37%, a significant increase in tear strength, enhanced elongation and a 100–500% improvement in abrasion resistance (according to a Taber test). As a result, the linings last much longer, reducing their need to be replaced and thereby lowering costs associated with production stoppages.
newGen Group has now launched a range of graphene-enhanced wear-protection liners for applications including reclaimer buckets, pipe spooling, dryer chutes and conveyor applications under its newly created ArmourGRAPH™ brand. Scaled trials of the liners are underway with key customers.
Further to wear liners, we are exploring a number of other high-volume markets for our graphene products. We are working with Steel Blue to increase the strength and reduce the weight of the composite toecaps employed in safety work boots for the oil and gas industries.
Research work undertaken recently by a number of institutions has demonstrated that graphene in elastomers increases their fire-retardance. While most of this work is understood to be at bench scale in laboratories, we have been conducting bulk sample test work in association with the University of Adelaide on the potential of PureGRAPH® to increase fire retardancy in polymer compounds, and the initial results have been impressive. According to the tests, while a base PU elastomer burns readily, the addition of approximately 1% w/w PureGRAPH® to the elastomer increases its limiting oxygen index (LOI) to 31.6%, meaning that under normal atmospheric conditions it will not propagate or support flame.
Watch the video for FireStop™, a fire-retardant coating for the protection of timber, below.
Graphene in Composites
It has also been shown that the addition of small amounts of graphene products to the chopped glass fibre-reinforced polyester styrene used for the production of large-area leisure industry items can increase their flexural strength by more than 30%. This enables less material to be used in the manufacture of these items, reducing weight, materials costs and the cost of labour associated with their hand lay-up. The use of graphene products in these applications has other benefits; the nanomaterial creates a water-resistant barrier and, as it increases the thermal conductivity of the material, its curing behaviour is more consistent.
Graphene in Energy Storage
Supercapacitors are capable of high power-density energy storage, can withstand multiple charge/discharge cycles and can be recharged quickly. The market for these devices is forecast to grow at 20% per year to approximately US$2.1 billion by 2022, but this growth may be limited by the lack of suitable materials for their production.
Supercapacitors typically employ microporous carbon nanomaterials with a gravimetric capacitance of 50-150 Farads/gram. Researchers at the University of Manchester have developed an electrochemical process that enables the production of microporous, metal oxide-decorated graphene materials with gravimetric capacitances of up to 500 Farads/gram from graphite. These materials will significantly increase the performance of supercapacitors in a wide range of applications, as well as increasing the available supply of materials for their production.
We have signed an exclusive worldwide licensing agreement with the University of Manchester through which we will gain exclusive rights to the University’s proprietary electrochemical process. In what will be a first step in the high-volume manufacture of these materials, the company is planning to build a pilot-scale production unit at its laboratories within the Graphene Engineering and Innovation Centre (GEIC) in Manchester.
As we have seen, the barriers to the commercial application of graphene products have been removed. It is now up to graphene suppliers, engineers and product designers to find ways of exploiting the properties of this remarkable nanomaterial in real-world applications.