Graphene-enhanced composite solution

Huntsman Advanced Materials is in the process of researching opportunities for developing graphene-enhanced composite solutions, with a view of incorporating graphene into its ARALDITE® epoxy resins and it is expected that such applications will significantly advance the market for nanocomposites.  Ultra-light yet immensely tough, graphene is stronger than steel but incredibly flexible. It also conducts electricity better than copper and can act as a barrier that not even helium can pass through.  

Sectors including medical, renewable energy and automotive in particular have been quick to investigate uses of the material – with improved photovoltaic cells benefitting from its excellent conductivity and transparency, stronger car tires that last longer thanks to its improved heat dissipation and pioneering research activities suggesting how the placement of graphene on the internal surfaces of intravenous catheters will improve the efficacy of chemotherapy treatments.  As the ‘the miracle material of the 21st Century’ even before its pioneers were awarded the Nobel Prize in Physics in 2010, commercial applications of graphene have been limited in some degree due to cost but also because of the complexity of processes involved in producing the material. However, with hundreds of companies and start-ups now involved in graphene research activities, this situation is likely to change and the market for polymer composites is expected to be a major beneficiary.

Developing nanocomposite technologies
With its exceptional properties, high aspect ratio and low density, graphene is ideally placed to further the development of a new generation of ARALDITE® epoxy resins.

Huntsman’s research involves using a low temperature plasma (under 100˚C) patented by one of its partners, Haydale Composite Solutions, which activates and allows modification of the nanomaterial’s surface energy and enables dispersion into a host medium, such as resin. Without using chemical acid treatments which can cause damage and degrade functional performance, this process maintains the structural integrity and mechanical strength of the final product.  Taking test plates cast from the activated graphene mixed into master batches of various concentrations of ARALDITE® epoxy resins, Huntsman has been conducting a series of physical, electrical and therma l tests in the continued evaluation of the composite performance.

So far, an ARALDITE® Euremelt hot melt resin and a general purpose epoxy resin have been specified to look at developing new prepreg applications using the former and advance other types of composite processes, such as filament winding and Resin Transfer Molding (RTM), with the latter.

Initial results have shown that these ARALDITE® graphene reinforced resins offer greater dimensional and thermal stability in addition to improved impact resistance, properties that through further investigation could offer major performance benefits. One particular area identified for future development is the market for electronic devices, where the electrical conductive properties of graphene-enhanced systems could help with electrostatic discharge and dispersion of excess heat, issues frequently linked to mobile phones and other portable devices.

Research into utilizing graphene’s electrical conductive properties in prepregs to improve the protection of composites against lightning strikes is also in place. In the future, it’s expected that there will be many application areas for structures prone to lightning strikes, such as aircraft, wind turbines and tall buildings.  David Hatrick, European Technology Director of Huntsman Advanced Materials comments, “We continue to make good progress in collaborative developments and have been particularly impressed with the improvements already made in the areas of thermal, electrical and mechanical performance.”

The excellent thermal conductive properties identified mean that these graphene-enhanced nanocomposite systems should theoretically be able to manage the dissipation of heat generated by the exothermic curing of the resin more effectively in the casting process and tests continue in this area. Harnessing graphene to solve this issue coul d potentially reduce cracking or voids occurring due to expansion and this would allow large volumes of composite material to be cast. Introducing graphene components into the composite mix could also deliver parts with high surface energy, improving the performance of coatings and paint finishes and reducing the need for primers.

As tests have also shown that the graphene-enhanced resin is stronger and lighter than traditional materials, there’s also scope to manufacture parts using less material, factors that could potentially move this technology from the high-end into the mass market for a wide range of applications – from sports equipment through to the mainstream automotive market. Mr. Hatrick added that: “This work is set to deliver the platform for a new range of graphene-enhanced ARALDITE® resins which will benefit the industrial composites, automotive, aerospace and other markets besides. We are now focused on the further demonstration of these resins in composites manufactured with a range of typical processes used by our end customers.”