Taylor Kanipe, a fourth-year PhD student at North Carolina State University in the US, is on a mission to develop a way of treating cotton fabrics that is more environmentally friendly and safer for the wearer. Alongside lab leader Richard Venditti, an expert on plant-based resources, Kanipe is working on a method that chemically alters seed oil from the cotton plant to create an alternative to current finishing agents based on formaldehyde or per- and polyfluoroalkyl substances (PFAS). Kanipe presented the work at the American Chemical Society’s fall meeting in Washington, DC.
Textile finishes for wrinkle resistance typically use formaldehyde-based resins, which easily bind to cotton’s cellulose fibres. ‘That’s bad – formaldehyde is toxic, particularly in large quantities, and with exposure over time it is a carcinogen as well,’ Kanipe tells Chemistry World.
Other fabric finishes used to provide water resistance traditionally use PFAS, which create a hydrophobic surface. But these substances are persistent in the environment and linked to several serious health conditions.
Instead, the material that Kanipe and her colleagues are using is epoxidised cottonseed oil (ECSO). The ECSO molecules bond strongly to each other, forming a hydrophobic polymer that repels water. They also create molecular bridges between the cellulose fibres, which helps make the material resistant to wrinkling, Kanipe explains.
To determine the finished fabric’s water repellent qualities, the researchers used a high-speed camera to measure the contact angle at which water droplets interact with the cotton surface.
Materials with contact angles greater than 90° are considered hydrophobic. While untreated fabric showed no observable contact angle, meaning that the water was fully absorbed into the fabric, fabric treated with ECSO showed a contact angle of 125° – signalling a significant increase in water-repelling ability.
Kanipe’s team is now aiming to develop a finishing process based on an emulsion of the epoxidised oil in water.
‘We are developing that right now, and this would remove solvents from our process – we wouldn’t have to use hexanes to apply it, which is a great bonus,’ Kanipe says.
She is conducting this research in the nearby labs of Cotton Incorporated, a nonprofit based in Cary, North Carolina that is interested in using cottonseed oil-based finishing agents.
Cotton Incorporated has lab-scale and pilot-scale equipment that make it possible to test how such water-based emulsions might work at a pilot scale. ‘If all goes well, and it is economically viable, that would be the next step,’ says Kanipe.
In the future, the North Carolina team wants to measure other performance factors in ECSO-treated cotton fabric, including tear strength and durability.
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