If you ask the proverbial ‘man on the street’ to name a material used to manufacture clothing, cotton would most likely be one of, if not the first, responses you would receive. This most traditional of garment-making fibres is in no way limited to conventional applications, however. David Styles takes a look at how the old textile dog continues to learn new tricks.
To quote the 2016 study, Cotton Utilization in Conventional and Non-Conventional Textiles –A Statistical Review: “Cotton’s success as a crucial raw material for the textile industry is unparalleled among all natural and manmade fibres.
“Cotton fibres have been used in virtually all categories of textiles because they combine physical and chemical characteristics that make them versatile in processing and desirable in use.”
Increasingly, the technical textile sector – which perpetually yields some of the most exciting creations in the industry – chooses to incorporate cotton into the most innovative of textile creations.
This follows a feature in the last issue of T.EVO which highlighted the expanding potential of cotton fibres through the development of naturally occurring, ‘in-built’ characteristics.
The research, conducted in Israel, presented a molecular study aimed at building functionality directly into lab-grown cotton. Through the addition of glucose modified at the C2 position, cotton fibres were cultivated so that they had naturally fluorescent or magnetic properties – both perfect for application in performance apparel.
Cotton expert Simon Ferrigno believes that in sports and outdoor apparel markets, cotton maintains its status as popular fibre due to its strong base qualities and predominantly positive public image; its popularity is also particularly high when global prices are favourable to manufacturers.
He told T.EVO: “It is good news innovation and legislation are driving demand for cotton in technical textiles. Joined up thinking by legislators should make sure that preference is given to fibres from sustainable sources such as organic or Better Cotton (as the EU Eco-Label does), and joined up thinking by manufacturers – if they follow due diligence guidelines – would lead to the same result.”
Cutting edge off-cuts
Scientists at the National University of Singapore have devised a method of converting waste cotton – sourced both as an off-cut but also from unwanted garments – into aerogel, a super-lightweight and versatile substance which has previously been produced using paper waste.
Despite dating back to the 1930s, aerogel has not been successfully commercialised due to its hitherto high production cost. Scientists have therefore been seeking new ways of manufacturing and consuming different types of aerogels. Cotton may just have provided the breakthrough.
Applications of aerogel are wide-ranging due to high levels of absorbency and low-level of thermal conductivity. Its unique properties make aerogel highly suitable for applications including oil-spill cleaning, personal care products, along with heat and sound insulation.
The cotton-derived aerogel is not only lightweight, but also highly porous and absorbent. Where it differs from paper-based alternatives is that it can be fabricated within eight hours; nine times faster than the lab’s prior invention and about 20 times faster than current commercial fabrication processes.
Professor Hai minh Duong said: "Each cotton aerogel pellet can expand to 16 times its size in 4.5 seconds – larger and more than three times faster than existing cellulose-based sponges – while retaining their structural integrity.”
During the research phase of the project, two military applications were also developed. In one experiment, the scientists created a thermal insulating jacket for military canteens which contained a layer of the cotton aerogel.
Due to the aerogel’s low thermal conductivity, it was able to maintain the liquid at a temperature of 0.1 to 1.0 ºC for over four hours; providing similar performance to existing products but with a much lighter weight.
The researchers also used the cotton aerogel to create absorbent capsules that are used to stop battlefield wounds from bleeding. These capsules – currently made of mini cellulose-based sponges – are injected into wounds via a large syringe to absorb blood and expand, applying pressure to the wound from the inside and stopping blood flow.
“The unique morphology of the cotton aerogels allows for a larger absorption capacity, while the compressible nature enables the material to expand faster to exert pressure on the wound,” Duong added.
The findings have been published in the scientific journal Colloids and Surfaces A, and the research team has now filed a patent for the cotton-derived aerogels and are looking for industry partners to commercialise the technology.
Cotton on show
The 2018 International Cotton Conference looks set to reflect the diversity of the fibre’s usage, featuring talks and demonstrations of the utilisation of cotton in a variety of technical textile processes and applications.
Attendees at the 34th annual conference in Bremen will hear from Franziska Stehle of the Fibre Institute Bremen, who will give a presentation on how structural products can be made which utilise the properties of cotton via manufacturing processes in which thermoplastic fibres are fused.
Milan Kelch, a research associate at the University of Applied Sciences in Bremen, will present cotton fibre used to reinforce plastics in the processes of micro-injection moulding and 3-D printing. This talk stems from a research project on biological materials which has suggested that in these processes, cotton outperforms bast fibres due to its fineness and uniformity.
From the Technical University of Lodz, Malgorzata Matusiak will present innovative 3D textiles made from both cotton and blends of cotton with synthetic fibres. Matusiak claims the studies confirm the excellent thermo-physiological comfort of these new textiles can be suitable for use in functional clothing.
Topics outlined in the event’s agenda include: digitalisation, research, and textile processes. The organisers say the conference “provides solutions to future challenges that are important not only to the specialist cotton world, but also to the entire cotton supply chain from processing to textile retailing.”
The emphasis on cotton developments is perhaps best illustrated by the work being done under the umbrella of Cotton Inc. in the USA. The organisation has updated its Cotton University platform, now called CottonWorks, to provide better education on the fibre’s potential from a grassroots level.
Following the 2018 reboot, the service for registered users now includes access to content such as webinars, workshops and the Cotton Inc. Textile Encyclopaedia, all of which is aimed at futureproofing cotton and further facilitating the industrywide adoption of cotton for technical applications.
It would appear that far from just operating as the fibrous building block of everyday, mundane garments and providing the perceived luxury of an Egyptian cotton bedspread, the future of a textile fibre which has been a staple of the industry for more than two centuries could lie firmly at the forefront of the technical textile revolution.