New life for old clothes

Since cotton naturally consists of cellulose, it should be possible to reuse cotton from clothes in the production of viscose. Based on this idea, Anna Palme, researcher at Chemistry and Chemical Engineering and active in Mistra Future Fashion, has, in her PhD thesis, mapped how recycled textile can be part of new clothes instead of being used as fill-material in sofas.

Viscose- a sustainable alternative
Today no new clothes are made from textiles that are left for recycling. Instead your recycled clothes become fill material in sofas, rags or isolating material in cars and such. At the same time cotton is resource demanding and is expected to become a luxury product in the future. One alternative is viscose which can be made from cellulose from resources from the forest. Anna Palme, researcher at the Department of Chemistry and Chemical Engineering at Chalmers and involved in Mistra Future Fashion, is now, in her PhD thesis, showing how a combination of cellulose from forest raw material and from recycled cotton may contribute to a more sustainable textile industry.

- Companies need scientific publications where they can compare how alike or unalike different raw materials are to start working with mixing cotton in viscose manufacturing. I have provided fundamental information about this. Some of the results are obvious for the textile industry but totally new for the forest industry, so some of the work is about bridging between the different industries, says Anna Palme.

Viscose is created from cellulose that is extracted from wood. Viscose fibres are then spun out of the cellulose. Anna Palme has investigated the possibilities for spinning new fibres through dissolving recycled cotton textile. She has conducted tests on worn-out textiles from hospitals and hotels. Today hospitals and hotels are paying to get rid of it so efficient recycling would be beneficial also for them. 
 



Results
Cellulose fibres are natural polymers, molecules shaped as chains, which consist of different layers. Anna Palme has studied all of these layers.

One problem with dissolving cellulose is how parts of the fibre are sticking together when they dry, so called hornification, which make them harder to dissolve.  One apprehension was that cotton possibly would develop more hornification the more it gets washed and thus become harder to dissolve, but instead it was found that cotton is exposed to hornification already out on the cotton field and isn’t affected more than it already is from getting washed. The results also show that although the cellulose fibre is broken down and becomes shorter when it gets washed, the fibre still after 40 washes is long enough for viscose production.

Also clothes that consist of cotton and polyester are possible to use. Anna Palme studied a method that is used today for separating polyester in ethylene glycol and terephthalic acid and discovered that also clothing consisting of both polyester and cotton can be separated with this method.

- The cotton passes through the process without getting damaged. It is possible to gain many useful materials from these clothes; cellulose for viscose production, ethylene glycol for defrosting of airplanes or polyester manufacturing and terephthalic acid for polyester production, says Anna Palme.

The forest industry is interested in Anna Palme’s results. They have moved from mostly thinking paper to also include clothing production as an important business, and since the stream of recycled textile not by far is large enough to dominate as a raw material for viscose production, the forest industry is needed. At the same time it is believed that cotton will only get more and more expensive due to the large areas cotton fields claim which, because of increasing populations, are needed for food production. Anna Palme believes that high-quality cotton will become a luxury product and that viscose will become more and more common.

- Absolutely. Cotton production has landed. We reached peak cotton in 1995 and it hasn’t increased since then. I have started visiting flea markets and often buy really old sheets since the quality was so much better in the past. And since we don’t want to wear only polyester clothes in the future viscose will become an important material, says Anna Palme.

​Link to Recycling of cotton textiles: Characterization, pretreatment, and purification in CPL.
More about Anna Palme's research
Read more about Mistra Future Fashion

 

Text: Mats Tiborn

Published: Fri 24 Feb 2017. Modified: Mon 27 Feb 2017