IDTechEx has invited a series of industrial players and leaders active in graphene commercialization to contribute their opinions about the state of the technology and markets. As part of article series, we will today hear from Directa Plus who write about the progress of graphene in textile applications. To contact Directa Plus directly please contact the author Dr Laura Rizzi on firstname.lastname@example.org
To learn more about the graphene markets please refer to our report on Graphene, 2D Materials, and Carbon Nanotubes 2016-2026: Markets, Technologies, and Opportunities. You can also meet with many industry leaders at our business-focused event Graphene Europe 2017 taking place on May 10th and 11th in Berlin, Germany.
G+ materials for the textile sector are obtained through the submission of natural graphite to a series of physical treatments. The first stage is plasma super-expansion, through which the graphite crystals are "exploded". This process is extremely efficient in separating the graphite planes without damaging their crystalline structure. Using this material, it is then possible to easily produce different forms of highly pure graphene. The subsequent processes include an exfoliation stage in water to obtain graphene-based inks and pastes, and a drying stage to produce powders. The entire process is based exclusively on physics - and not on chemistry: in fact, in our plant we do not use any chemical additives or solvents. This key feature of our technological process allows us to produce graphene-based materials that possess unique characteristics while being safe for human contact, as certified by a series of analyses conducted by an independent testing agency.
The use of graphene in the textile sector is a good demonstration of Directa Plus' business strategy: to bring disruptive innovation to existing markets and mature sectors, with products targeted at consumers. This approach is not without difficulties as mature industries are often averse to change and reticent to experiment with new solutions. That said, in the current textile market there is a demand for technical innovations to create new garments that can adjust to different temperatures and physical conditions.
For a graphene producer, the key consideration is to create materials and technologies that can be easily integrated into current production methods. This can be achieved in the textile sector, for example, by applying graphene via silk screen printing or within a membrane. In so doing, it is possible to shorten the time to market and to offer consumers cutting-edge products.
The foremost innovation that graphene has brought to the textile sector is that it has revolutionised the whole concept of technical performance of fabrics and thus of garments. Traditionally, fabrics are not able to "talk" to the body. The focus has been on fabric performance in terms of the relationship between the human body and the environment - that is, on through-plane properties - such as textile breathability or impermeability.
Now, thanks to graphene, the body can "talk" to the fabric, and the textile can actively respond. The in-plane properties optimise fabric performance due to the interaction between the textile and the human body by distributing heat generated by the body to prevent the creation of hot-spots and dissipating it when needed. This approach to thermal comfort in garments, derived from the bidimensional and planar nature of graphene, is in itself revolutionary and extremely effective.
In addition, due to the thermal circuit created by the graphene, which is placed in contact with the human body, it is possible to adjust the body temperature without using an external source of energy such as batteries. Instead, it simply exploits the thermal flows naturally generated by the human body, and without affecting the fabric's other features such as breathability and impermeability.
Figure 1. Example of a graphene thermal circuit. On the left, a fabric printed with graphene and on the right, a non-printed fabric. The heat from the thermal source is spread through the thermally conductive graphene print.
Graphene can also render fabrics electrically conductive - enabling, for example, data transmission, which renders the garments interactive - providing numerous opportunities in terms of wearable technologies and Internet of Things. In this case, the graphene fabrics replace the metallic materials currently used, which has many advantages such as lower weight and volume, and reduced maintenance requirements thanks to flex resistance and fastness.
Moreover, graphene fabrics are bacteriostatic, therefore preventing the proliferation of bacteria without killing them. As a result, graphene fabrics are suitable for skin contact because they do not risk affecting skin flora.
The use of graphene in the textile sector is an example of the incorporation of a nanomaterial within large and complex industrial supply chains. To be successful, this process requires:
- being able to provide the correct grade of graphene, with a well-defined particle morphology, in the requested quantity to satisfy customers' expectations and textile producers' needs (cost-containment);
- finding the optimum means for incorporating graphene into final products (mixing methods, concentrations, graphene-based semi-milled, garment engineering, etc); and
- supplying "certified" graphene, from a legal and toxicological perspective.
The culmination of two years of work resulted, recently, in to the first graphene garments becoming available on the market, developed with our partner Colmar, while Grafytherm® and Grafyshield® membranes, commercialised by Directa Textile Solutions, are generating considerable interest in the textile sector.