Engineers recycle jeans into artificial cartilage Wednesday, 15 August 2018

Who would have thought that denim jeans could be transformed into artificial cartilage for joint reconstruction? Well they can, thanks to advanced textile recycling methods pioneered by engineers at Deakin University.

Senior Lecturer in the School of Engineering, Dr Nolene Byrne, and PhD candidate, Beini Zeng, have discovered how to dissolve denim and manipulate the remains into an aerogel. This low density material has a range of uses including cartilage bioscaffolding, water filtration, and as a separator in advanced battery technology.

Working with the university’s Institute for Frontier Materials (IFM), Dr Byrne said the process had worked because denim is made from cotton, a natural polymer comprised of cellulose.

"Cellulose is a versatile renewable material, so we can use liquid solvents on waste denim to allow it to be dissolved and regenerated into an aerogel, or a variety of different forms," Dr Byrne said.

Aerogels are a class of advanced materials, sometimes referred to as 'frozen smoke' or 'solid smoke', and because of their low density they make excellent material for bioscaffolding, absorption or filtration.

"When we reformed the cellulose, we got something we didn't expect – an aerogel with a unique porous structure and nanoscopic tunnels running through the sample," Dr Byrne revealed.

She believed the sticky nature of the denim cellulose solution was likely responsible for the unique aerogel structure which is ideally suited for use as synthetic cartilage.

"That's exactly what cartilage looks like – you can't 3D- print that material – and now we can shape and tune the aerogel to manipulate the size and distribution of the tunnels to make the ideal shape," she revealed.

IFM's Dr Wren Greene, who tested the suitability of the aerogel materials as cartilage-like bioscaffolds, said the similarities were “remarkable”.

"The similarity in the pore network structure of these aerogels and cartilage tissues – even down to the dimensions, orientations, and density distribution of pore channels – enables these materials to replicate a special type of 'weeping' lubrication mechanism used by cartilage to protect against wear and damage," she said.

Apart from its applications as a cartilage supplement, Dr Byrne said the denim recycling technique would also help reduce textile waste.

"Textile waste is a global challenge with significant environmental implications, and we've been working for more than four years to address this problem with a viable textile recycling solution," she explained.

"With population growth and the development of third world countries, combined with today's rapid fashion cycles, textile waste is always increasing, leading to millions of tonnes of clothes and other textiles being burnt or dumped in landfill."

Dr Byrne said because environmentally-friendly chemicals were used and they can now address the limitations of other less cost-effective methods.

"We are now entering pilot-scale trials and look to be at commercial scale within 3-5 years, with industry support," she revealed.