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Silverson mixers key in scaling graphene production

New research focuses on challenge of commercialising promising nanomaterial

Scientists at the forefront of research into graphene production identified the mixing process as the key stage in developing this emerging technology from the lab bench to a commercial scale.  And they knew just who to go to for help – Silverson Machines.

Known for the excellent scalability of its mixer range, Silverson recently found itself playing a significant supporting role in research into graphene production. One of the company’s L5M-A High Shear Laboratory Mixers, used to exfoliate graphene from graphite, was featured in a newly published article in the journal Nature Materials entitled, “Scalable production of large quantities of defect-free few-layer graphene by shear exfoliation in liquids.” The research team at Trinity College Dublin, Dublin, Ireland, used the L5M-A in its initial trials not only because of its excellent all-round performance, but because they knew they could later test their scale-up theory in larger Silverson production scale machines. “Previously we had used Silverson mixers to disperse carbon nanotubes, which had proved to be very effective,” explains Keith Paton, Ph.D., researcher-in-residence, Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, and one of the research paper authors.

“Scale-up can be a tricky problem for manufacturers,” relates Ian Snowball, a Silverson sales engineer, who assisted the university research team. “You need to be able to replicate your lab results on a large scale in production, and many specialised laboratory mixers have no production scale counterparts.  At Silverson, we’ve designed, engineered and constructed our laboratory mixers to the same tolerances as our production units. In fact our entire range of mixers produce comparable rotor tip speeds and shear rates. And because of this, our machines produce scalable results.” This reputation is what drew the Trinity College Dublin research team to use Silverson machines in their trials.

Stronger, lighter, thinner

Ever since it was first isolated from graphite in 2004, graphene has captivated the collective imagination with its possibilities. Incredibly strong, extremely thin (one million times thinner than a sheet of paper) and highly conductive, graphene is a two-dimensional material consisting of a single layer of carbon atoms arranged in a honeycomb structure. Because of its unique properties, graphene is prized as a material for use in electronics, smart packaging, bioengineering, super capacitors and more.

While the potential applications for graphene are vast, obtaining sufficient quantities to commercialise into large-scale production has been a major roadblock. The researchers knew that high-shear mixing of graphite in a suitable solvent could produce small quantities of usable graphene. In fact, they found this could be achieved with a standard kitchen blender. The challenge though was to scale-up the method to enable them to produce large quantities of graphene for commercial applications. This is when Silverson scale-up expertise came into play. “The availability of the test labs at Silverson’s site, where we were able to test the scalability of the process was a key advantage for the development of the process,” says Paton.

Using Silverson high shear mixers, the research team was able to develop industrially scalable methods for producing defect-free graphene. The team worked in Silverson’s state-of-the-art Applications and Testing Centre in Chesham, England, where they were able to trial various production-scale machines. “By coming to our Applications and Testing Centre, the team was able to not only test the full range of our machinery, but also tap into our scale-up knowledge. This is an area in which Silverson has a great deal of experience and has conducted thousands of applications research trials,” states Snowball. “We’re proud to be part of this successful project.”

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