Excerpt from an article originally published in Composite Manufacturing Magazine.
After a slow start, composites manufacturers are taking advantage of graphene’s unique properties. In 2004, working at the University of Manchester in the United Kingdom, researchers Andre Geim and Kostya Novoselov produced graphene, the world’s first two-dimensional, man-made material.
In the following years, graphene was hailed as a wonder material because of its many remarkable properties. Despite being extremely lightweight and a million times thinner than a human hair, graphene is the world’s strongest material, with 200 times the tensile strength of steel. It has high electrical conductivity and thermal conductivity, is practically transparent, is impermeable and extremely flexible and stretchable. What makes graphene truly unique, however, is its ability to provide all these properties at once.
“With most materials, if you want to get one beneficial property you have to introduce some negative aspects, but with graphene you can impart multiple properties simultaneously and without the typical tradeoffs in many, many cases,” says Terrance Barkan, executive director of The Graphene Council.
Like many other high-tech discoveries, graphene didn’t initially live up to the hype. Early attempts to capitalize on its properties were unsuccessful, and many companies became dubious about its ability to deliver what was promised. There were several reasons for these failures.
Early adopters were also confused by graphene’s unusual behaviour. Composite material manufacturers, for example, are accustomed to adding more of a substance to a composite when they want to increase the properties it imparts to a material. But graphene has the reverse effect; reducing the quantity used generally improves the graphene-enhanced composites’ performance. Companies that initially added 1% graphene by weight to their composite materials achieved better results when they decreased the amount to 0.5% by weight. “The magic of this material is that an incredibly small amount of it can dramatically improve the performance of other materials,” Barkan says.
With continued research and experimentation, companies have gained a better understanding of graphene’s behaviour and are finally realizing its benefits. The nanomaterial is proving to be a valuable asset for the composites industry since it can be used for thermoset and thermoplastic composites, incorporated into glass, carbon and basalt fibres, and used with a variety of resins.
Ford Motor Company has been a leader in the adoption of graphene-enhanced composite materials. In October 2018, it announced that it would include foam made with graphene in more than 10 under-hood components, including pump covers and fuel line covers, on the Ford F-150 and Mustang.
Debbie Mielewski, Ford’s senior technical leader in materials sustainability, says the company has incorporating graphene into urethane foam. Working with XG Sciences and Eagle Industries, the Ford team developed a foam that included 0.2% by weight graphene. “We got a 25% improvement in high-temperature properties and an almost 30% improvement in noise absorption properties.
She says the graphene helps absorb the sound much better, gives a quieter ride in the cabin and can withstand the heat – all important qualities under the hood.
Ford might someday use graphene urethane foams for engine covers and for headliners and door panels in vehicle cabins. “We’re also thinking about going back to hard plastics, but you have to be a little more creative because I think is not going to be easy to distribute there,” Mielewski says.
Meanwhile, in Europe, Briggs Automotive Company has reduced the weight of its single-seat racer by more than 15% using graphene-enhanced prepreg for the body panels. The tooling for the parts, also made from graphene-enhanced prepreg, enabled the automaker to reduce the process time. “They could heat the tooling up quicker and cool it down quicker,” says Dickie.
Barkan suggests that Ford’s use of graphene may be a catalyst for its inclusion in more composite parts. “Many companies are somewhat conservative. They don’t want to be the first. They want to see that somebody else has proven the market,” he says. “So I think when we see a large-scale manufacturer using graphene in a way that takes them a step change up in competitiveness – when they get a 25% to 30% improvement for a class of materials – the rest of the competitive field has to decide how they’re going to act.”
Composite materials containing graphene are now being used in the manufacture of everything from golf balls, sports racquets and training shoes to fire retardance coatings and construction materials.
“One company, Haydale, has just come out with a prepreg material specifically designed to be used for lighting strike protection,” says Barkan. “That would eliminate having to use a copper mesh or a silver nanowire mesh to protect aircraft.” That same technology could be used for unmanned aerial vehicles and offshore wind turbine blades.
The University of Manchester’s Graphene Engineering Innovation Centre (GEIC) is working with industry customers on construction materials, incorporating graphene into concrete and asphalt mixes. Adding very small amounts of graphene powder to concrete mixes dramatically increases concrete’s compressive strength and reduces the amount that builders need by 30%. Since concrete production releases a lot of CO2 into the atmosphere, the use of graphene provides an environmental benefit.
Putting graphene into polymers, foams and textiles can improve their fire retardancy. “Several industries looking at fire prevention in aerospace have had some very positive results in thermoplastics and textile materials,” says Scullion. This flame retardancy is usually just one of the many beneficial properties that graphene delivers for these applications.
Graphene imparts anti-biofouling and anti-corrosion properties to coatings, and that could have a global economic impact. “Biofouling on the hulls of commercial ships costs the shipping industry $36 billion a year in extra diesel fuel because it creates a drag in the water,” says Steven Rodgers, technology consultant and principal, EmergenTek, and a board member of the National Graphene Association. “Corrosion on bridges, rebar, automobiles globally costs about $2.4 trillion dollars.”
Because graphene is a very flexible material, it can be used as a sensor in composite products. Crash helmets and sports helmets could be designed so that they measure the impact of a ball or other object; if someone gets hit in the head it would be easier to tell if they had a concussion and needed further medical attention. Incorporated into vehicle parts, graphene could provide a variety of more sensitive and less power-consuming sensors.
“With graphene, composites manufacturers can take advanced composites, which are already amazing, and make them even better,” says Barkan. Composites with graphene may now be able to compete directly with metals because of the strength improvements the nanomaterial imparts. Adding graphene to thermoplastics raises the thermal deformation temperature, so they can now be used in applications in temperature ranges where they couldn’t be used before.
While graphene may not be a wonder material, its multiple properties should open up a wide range of new opportunities for the composites industry. “As prices for graphene and graphene-related materials come down and the methods for making graphene at scale are refined, we should start to see more and more graphene composites in the market,” says Lisa Scullion, application manager at the GEIC. “The incredible properties that graphene materials can bring, means that there is a huge drive to make this happen.”
See the full Composite Manufacturing Magazine article here.