Researchers at TU Graz Turn Textile Waste into Paper
The idea is not new, but was now rediscovered: Researchers at the Austrian Technical University of Graz have found a way to recover the cellulose fibers from used clothing and utilize them to produce cardboard and other packaging materials.
As reported by the university, in Austria alone around 220,000 tons of textile waste is produced every year, of which almost 80 percent is incinerated. As a result, valuable raw materials are lost. A team led by Thomas Harter from the Institute of Bioproducts and Paper Technology has come up with a solution to this problem. The researchers have developed a process to recover the fibers from cotton-based used textiles and use them to produce paper for packaging materials.
According to Thomas Harter, technically converting textile fibers into paper is a downgrade. “However, it has a major advantage from an environmental point of view. The paper cycle is highly closed, with recycling rates of over 90 percent in the packaging sector. If we bring valuable textile fibers into this cycle, they remain usable for a long time.” Recycled textiles could be an important source of raw materials for the production of packaging paper and help to reduce the amount of paper imports currently used for this purpose.
Very similar to normal papermaking suspension
To make paper from old items, clothing is cut into small shreds and soaked in an aqueous solution. This mixture of water and shreds is milled to separate the interwoven cotton fibers without knotting or clumping. As part of his master’s thesis, Alexander Wagner determined the most suitable beating machine, the necessary processing time, and the optimum ratio of water to textiles to extract the maximum amount of usable fibers from the textile waste. “At the end of our tests, we obtained a suspension that is very similar to a normal papermaking suspension and that we can process into paper using established methods,” Thomas Harter was quoted.
Significantly more tensile strength than conventional recycled paper
As described by TU Graz, the paper with textile content hardly differs from ordinary recycled paper; it is slightly brownish with occasional colored speckles, which come from colored clothing. However, these splashes of color were irrelevant for carton boards and other packaging materials. Tensile tests have shown that the addition of textiles increases the strength of recycled paper. “Even with a textile-based proportion of 30 percent, the paper is significantly stronger, while the processability remains the same,” Alexander Weissensteiner informed, who is also working on optimizing the recycling process as a master’s student. This would be due to the length of the fibers. “The fiber lengths of recycled waste paper are quite short. At 1.7 millimeters, our recycled textile fibers are significantly longer.”
The researchers’ next goal is to reduce the energy consumption of the beating process. In addition to additives such as light acids and alkalis, they also test enzymatic pre-treatments to support fiber disintegration in the beating unit. “We also want to take the next scaling step and implement the process on industrial devices,” Thomas Harter stated.
(Published in GLOBAL RECYCLING Magazine 2/2025, Page 37, Photo: Lunghammer / TU Graz)
