Graphene and nonwovens – a winning combination
Dubbed ‘the new wonder material’, graphene is poised to have a significant impact on the nonwovens industry in the next few years, having already been successfully employed in smart geotextiles and with pending new applications in the huge hygienic disposables industry, as well as in filter media and apparel.
It was at the University of Manchester in 2004 that Professors Andre Geim and Kostya Novoselov first worked out how to isolate and extract one atom thick, two-dimensional crystal graphene from graphite, leading to their Nobel Prize for Physics six years later.
The current global market value for graphene is estimated to be around $50 million and is expected to grow to more than $390 million by 2024, but this could be just the tip of what turns out to be a considerable iceberg.
Graphene is the strongest material ever tested and has many other uncommon and useful properties. It efficiently conducts heat and electricity while being nearly transparent, yet is surprisingly opaque for a 1-atom-thick layer. Added to this, it is the most stretchable crystal in existence and is impermeable to all gases except water vapour
Not surprisingly, UK investment in graphene’s potential has been considerable, with the £61 million National Graphene Institute (NGI) established in 2015, followed by the £60 million Graphene Engineering Innovation Centre (GEIC) at the end of 2018, both in Manchester.
The Graphene Flagship, launched by the European Union in 2013, meanwhile represents a coordinated research initiative on an unprecedented scale. With a budget of €1 billion, it is the EU’s largest research initiative ever.
It has been on the other side of the world, however, that the first applications for graphene-coated nonwovens have been commercially established.
Bidim C nonwovens manufactured by Geofabrics Australasia are conductive geotextiles designed to provide an effective, lower cost method for designers and installers of lining systems for landfills, mines, dams and water storage facilities to undertake liner integrity surveys, providing reliable gas and liquid leak detection of liner ruptures – as small as 1mm in diameter.
The nonwovens are coated with imgne X3 conductive graphene coatings manufactured by Imagine IM of Rosebery, New South Wales, Australia.
Bidim C nonwovens have proved particularly effective as leak detectors at coal seam gas mining sites, where they allow operators to reduce the risk of of toxic leachate getting into groundwater and aquifers.
Haydale Technologies, of Ammanford, UK, has subsequently acquired an exclusive license to run the processing technology of Imagine IM in order to establish the capability to apply graphene-based conductive coatings to geotextiles in North America.
The initial target of another UK-based company, G2O Water Technologies, which has just secured over £1 million in private equity funding, is the filtration sector.
G2O was established in 2015, following many years of research into how nanomaterials, particularly graphene, can be used to reduce the cost and increase the performance of water-filtration products.
G2O is now using a graphene derivative, graphene oxide, to produce a highly effective coating for existing membrane and nonwoven-based filtration systems.
“The beauty of our technology is you do not need to replace the water filtration system, we can improve what’s already there,” explains the company’s chief technology officer David Pears. “By increasing the flux and rejection rates, the coatings reduce the amount of energy required to operate the systems, thus reducing the cost of water filtration.”
G2O also notes that a major challenge in the design of hygienic disposables is in achieving rapid fluid inlet, reduced wet back and storage, and retention of either urine or menses in a thin profile, as well as the active suppression of malodour.
“The remarkable liquid through-flow and physical molecular separation capabilities of graphene oxide provide exciting potential to improve the performance of hygienic disposables, by reducing inlet time and increasing liquid storage capacity, as well as the separation of molecules responsible for malodour,” says Pears. “This combination of functions is fundamental to the performance of hygienic disposables and commercial solutions do not yet fully meet all these criteria.”
The Italian graphene manufacturer Directa Plus has also already achieved success with its Graphene+ brand of coatings in interlinings for the Winter sports apparel of leading brands such as Colmar and Eurojersey, as well as in protective clothing.
Graphene+ enables fabrics to act as filters between the body and the external environment, ensuring the ideal temperature for the wearer. As a result of the thermal conduction of graphene, the warmth produced by the human body is preserved and distributed evenly in cold climates, yet dispersed in warm climates, and allows an even body temperature to be maintained during physical activity.
The Directa Plus production process is based on a proprietary technique called ‘plasma super expansion’. Starting from natural graphite, each step of the process – expansion, exfoliation and drying – creates graphene-based materials ready for a variety of uses and available in different forms such as powders, liquids and pastes. An important factor for commercial customers is the highly-consistent graphene that results from this process and no chemical or solvent additives are required.
“Not only is our Graphene+ chemical-free and made from an abundant, safe and non-toxic raw material – graphite – we are attaining high purity and consistent quality,” says Razvan Popescu, Directa Plus Chief Operating Officer.
The latest partner for Directa Plus is Arvind – India’s largest textile manufacturer - which also has nonwoven interests
Arvind has initially started incorporating Graphene+ into denim jeans and jackets but says this is just the start.
“In general, graphene is the magic product that has been able to do anything so far but get out of the lab,” says Stefano Aldighieri, Arvind’s creative director. “For a number of years, R&D centres have been talking about all of the wonderful things it could do, but when we decided to become involved, the crucial thing was to get things out in the market as soon as possible, and we opted to go for the low-hanging fruit, which was simply wear and comfort in textiles.”
The next stage in the partnership between the two companies, he adds, will be to “really exploit the potential for abrasion resistance in apparel, with a product that is two hundred times stronger than steel.”
“We are only at the beginning of what we see as a sustained evolution. I see a lot of potential in nonwovens and a further idea is the creation of electronic circuits on apparel for applications such as heating and power charging.”