A closer look at mechanical methods

In the present day, solely a fraction of all textiles are recycled. Katarina Lindström desires to vary that. Her doctoral thesis in Textile Expertise on the Swedish College of Textiles contributed distinctive data about mechanical recycling: which processes and supplies give one of the best outcomes.

In recent times, the necessity to tackle used textiles has turn into more and more acute. With new legislation by the European Union, all textiles should be collected individually and in lots of municipalities, recycling facilities have rapidly turn into inundated.

On the identical time, we see within the information one other draw back of overconsumption, the place garments and textiles are dumped overseas, removed from the eyes of Swedish shoppers.

These questions Lindström, a textile engineer who studied on the Swedish College of Textiles, College of Borås. When she began her doctoral research just a few years in the past, she selected to concentrate on mechanical recycling.

“So far, very little about the subject has been described in the research. The industry does have knowledge on the topic, but these are trade secrets that it likes to keep to itself. If we are to achieve the goals of a more sustainable textile industry, we must become more open with this knowledge,” mentioned Lindström, who has written her thesis with the intention of creating its content material accessible to the trade.

Each millimeter counts

“Unlike chemical recycling, mechanical processes do not consume as much water or chemicals. Broadly speaking, the textile is cut and torn into smaller pieces in different stages. Sometimes water or lubricant is added to make it easier to separate the fibers from one another. This process is tough on the fibers, which are, of course, designed to hold the textile together,” defined Lindström.

“If the fibers are too finely broken up during the process, it is not possible to spin them into new yarns. In this case, the material is downgraded to fill material or nonwoven fabric. In my tests, I have shown that there is a lot you can do to get longer, open fibers that could be used for yarns and textiles.”

In her work, she has carried out numerous checks and developed new strategies. A few of these strategies check friction between fibers and a few see how open a fabric is. On this context, “open” signifies that the fibers have been free of the textiles.

Precious outcomes for the trade

Within the comparability of two lab-scale recycling machines, woven and knitted constructions and yarns with completely different twists have been examined. The intention was to see how the development itself impacts recyclability. The outcomes confirmed {that a} looser textile with a decrease twist yielded longer fibers. And the much less mechanical processing, the higher the standard of the fibers. To realize this, lubricants have been added.

“Lubricants reduce friction, and this proved to be particularly successful with polyester. With lubricants, less heat was required in the process, which is otherwise a challenge as it can lead to the polyester melting. I have also been able to show that the length of the fiber is affected by the direction in which the textile is fed into the machine,” mentioned Lindström.

She has additionally imitated how the usage of a garment impacts recyclability, i.e., how garments are damaged down by use and the way it impacts the size of the fiber. Along with Grasp’s college students from Saxion College of Utilized Science within the Netherlands, she has investigated how the proper of pre-treatment can present longer fibers and enhance spinnability.

Many textiles right now are fabricated from combined supplies. They’re tougher but not unattainable to recycle, mentioned Lindström, who hopes that her outcomes will be useful when clothes recycling will increase. It’s a essential piece of the puzzle for a extra sustainable world. However recycling can by no means be the one answer.

“The best thing is that we use our clothes more, repair our garments when needed, and re-design them when they go out of style. In this way, as little energy as possible is used,” mentioned Lindström.

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College of Borås