Recycling methods turn textile waste into functional coatings

(Nanowerk News) In an effort to make textiles more sustainable, a new method allows researchers to chemically break down old clothing and reuse polyester compounds to make fire-resistant, anti-bacterial or wrinkle-free coatings that can then be applied to clothing and fabrics.

Proof-of-principle studies provide hope for the unsustainable textile, apparel and footwear industries which together generate 20% of global solid waste. Many so-called recyclers end up illegally disposing of textiles as waste in countries across Asia and Africa.

“We think our clothes are recycled or reprocessed, but most of the time they are actually sent elsewhere as solid waste,” said Juan Hinestroza, professor of fiber science and clothing design and director of the Textile Nanotechnology Laboratory at Cornell University. “Our ultimate goal is to offer a pathway to reuse this material.”

The paper, “Upcycle of Dyed Polyester Fabrics into Copper-1, 4-Benzeedicarboxylate Metal-Organic Frameworks,” is published in the journal Industrial & Engineering Chemical Research (“Recycling Dyed Polyester Fabrics into Copper-1,4-Benzenedicarboxalate (CuBDC) Metal-Organic Framework”), describes the process of cutting textiles into strips and chemically decomposing them into a soup of raw materials, dyes, additives, impurities and esters. The metal solution is added and the building blocks of the polyester share an affinity for the metal, and selectively link together the metal compounds to form a small cage – called a metal-organic framework – which settles to the bottom of the soup.

The cages that are formed are then used to make linings, which may require minor structural changes to adapt each to a particular use. This may include coatings that make a permanent press shirt unwrinkled, antibacterial surgical gowns or scrubs, or baby or industrial clothing that requires flame retardant protection.

“One of my lab’s goals is to create a universal coating that will serve all of these purposes, although we are still far from it,” said Hinestroza.

Yelin Ko, a doctoral student in human-centered design, is the paper’s first author. Prior to this research, some people believed that the dyes and impurities in the mixture would interfere with the process, but the proof-of-principle of this method – known as controlled crystallization – demonstrated that the polyester-derived binder could seek out and stick to metals. compound in solution, regardless of the other materials present.

The research describes a closed-loop process, in which discarded materials can be reused and contribute to a circular economy – a focus for many sustainability researchers at Cornell, said Hinestroza.