Australian research could help manufacturers beat the heat with graphene

A burning Dodge Charger 1:24 scale model.

Australian research has recently shown graphene‘s usefulness in giving materials improved thermal properties. Brent Balinski spoke to ANU Associate Professor Shannon Notley about getting this out of the lab.

Since atomically-thin graphene was discovered in 2004 by literally pulling apart graphite with sticky tape, it’s had an exciting early life.

Things really kicked off after a pair from the University of Manchester shared a Nobel Prize in Physics in 2010 for their discovery. Since then, researchers (mainly) and companies all over the world have been trying to put graphene’s remarkable properties to practical use.

The Scotch tape and pencil lead method, however, is an obviously hard thing to scale, so many of these researchers have set about developing a variety of other ways.

“For us the challenge was that graphene was produced in very small volumes: less than micrograms,” Shannon Notley, Associate Professor at Australian National University’s Research School of Physics & Engineering, told Manufacturers’ Monthly.

Shannon Notley

“So you couldn’t do any serious research and study on it… and we could [later] increase the amount of graphene produced at any given volume by a factor of about 100.”

The method Notley developed, Pristine Graphene, uses ultrasonics to exfoliate graphene sheets from graphite in a liquid. It is currently at a Technology Readiness Level 7.

Aspects of the “wonder material” that cause excitement are many, including strength, thermal and electrical conductivity, and optical properties.

It is a material, notes an article from a few years ago, “that is just one atom thick, 300 times stronger than steel, harder than diamond, a fantastic conductor of heat and electricity and super-flexible to boot.”

For Notley, he has decided to focus on the thermal management potential of graphene, as well as ways to produce the material.

“I think one of the things to get across about graphene is it shouldn’t be looked at as a single type of technology – they’re a family of technologies that have come about through different production techniques,” he explained.

“I think with our process, now that we’ve become a little bit more aware of some of the challenges with translating the research from some of these fantastic properties to scaling up different volumes, these types of large applications. Really, you need to think about where it’s going to end up when you start to produce it, and try to play to your strengths as much as possible.”

Notley co-led research published recently that could point the way for creating lightweight, heat-resistant plastics, taking several steps out of the process of impregnating graphene in resins. A provisional patent has been lodged for this method.

It produces graphene in a curable surfactant, which is based on the chemistry of benzoxazines (thermosets used in some high-temperature aerospace applications).

Epoxy tends to degrade at about 150 degrees C. Benzoxazines, however, are typically stable at greater than 300 degrees.

“So we were looking at can we find a compatible chemistry, and we came up with a way of actually producing the surfactant itself, which was able to polymerise with very high thermal stability, but very high thermal conductivity as well, because of the high loading of graphene,” said Notley.

He believes that graphene could be developed into thermal management solutions such as in phase change (heat storage) materials and in electronics.

flexegraph

His vehicle for production and sales, FlexeGRAPH, operates a pilot plant with a two-tonne per year capacity at ANU, and plans to formally spin out soon. Approximately 1,000 batches of graphene have been produced there so far.

The company also produces other 2D materials created using their method. There are “about 200” such atom-thick materials out there that can be made. FlexeGRAPH produces others (in dispersions) besides graphene, including talc, molybdenum sulphide and boron nitride. The latter offers potential according to some, due to having high thermal conductivity but also being electrically insulating.

Market pull for graphene and its thermal management offerings still has to be developed, with a big, complex value chain of resin suppliers at one end and aerospace companies at the other.

Commercialisation will include a lot of conversations with a lot of people within that chain. And due to the high costs of the material, this will limit where it might make sense to use.

Adding to this, graphite with the desirable high grain size also means higher costs.

Scale things up, though – an problem for graphene from the beginning – and issues around cost will change.

“Certainly there’s a need for better thermal management in general when it comes to either fluids or aerospace, or microelectronics for that matter, too,” he added.

“When you think about increased computing power in smaller spaces – it leads to more heat. So here’s certainly an appetite for new strategies for thermal management. The challenge to deal with is cost. But that will change as graphene production ramps up.”

Images: ANU