Rought denim background
Original Published Date: 
Wednesday, October 30, 2019

Full article issued by the ARC Research Hub for Future Fibres.  

ARC-supported researchers have reported an efficient, low-cost method that can convert waste denim into viscose-type fibres that are either white or the original colour of the garment. The new technique improves on existing recycling methods which can be inefficient and expensive, and promises to reduce both landfill and the need to grow so much new cotton.

Previously, researchers have used ionic liquids—salts that are liquid, not solid—to dissolve cotton textiles into their cellulose building blocks. The cellulose was then spun into new viscose-type fibers that could be woven into textiles. However, ionic liquids are expensive and difficult to work with because of their high viscosity, so Dr Nolene Byrne and colleagues at the ARC Research Hub for Future Fibres, based at Deakin University, wanted to find a way to reduce the amount of these solvents required to recycle denim into regenerated cellulose fibres.

The researchers ground three textile samples (blue denim fabric, red denim pants and a mixed-colour T-shirt) into powders. Then, they dissolved the powders in a mixture that included dimethyl sulfoxide (DMSO), which allowed them to use much less ionic liquid than other methods. In addition, DMSO reduced the viscosity of the ionic liquid solution, making it easier to spin the cellulose into new fibres. Because DMSO is much cheaper than the ionic liquid, the new process reduced the cost of solvent by 77%.

When they pre-treated the textile powders with a sodium hydroxide solution, the researchers could produce white viscose-like fibres. Without this step, the fibres retained the colour of the original item, which conserves water and energy that would otherwise be required for textile dyeing. 

Photo credit: 

Image: Rought denim background. Credit: Creativity103 (CC BY 2.0).