SKZ launches new research project “CloseT” for sustainable recycling of used textiles

Until now, old textiles have mainly been recycled thermally, which irretrievably destroys valuable polymer resources and prevents the opportunity for sustainable reuse. The “CloseT” project focuses on chemical recycling using solvolysis. This involves chemically recycling mixed old textile fibers in a continuous process using a twin-screw extruder. The reaction products obtained in the recycling process are to be used directly as raw materials in plastics processing. “We want to create a sustainable alternative that not only conserves resources but also opens up new value chains,” explains Dr. Hatice Malatyali, project manager at SKZ.

Material separation and industrial implementation
Suitable synthesis routes are first developed in the laboratory and then transferred to the continuous process. One focus is on the efficient separation of mixed fibers such as cotton and PET. Cellulose acetate is to be produced from the cellulose fibers obtained, while the degraded PET fractions are repolymerized to rPET.
“With this project, we are making an important contribution to reducing textile waste and strengthening the circular economy,” emphasizes Prof. Dr. Andreas Hartwig from the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research IFAM.

Funding and duration
The “CloseT” research project (Ref. 9D867) will be funded by the Volkswagen Foundation from November 1, 2025, to October 31, 2029, through the “Circularity with Recycled and Biogenic Raw Materials” funding initiative. SKZ – KFE gGmbH and the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research IFAM would like to thank the Volkswagen Foundation for its support.

More information on the SKZ research area Compounding