A consortium of 16 public and private sector organisations under the name 'WhiteCycle' has set itself the goal of establishing a comprehensive and closed-loop recycling system for plastic waste. The German Institutes for Textile and Fibre Research Denkendorf (DITF) are part of this consortium and will make their contribution with a new synthesis method for processing recycled plastics.
Under the leadership of Michelin Group France, the consortium 'WhiteCycle' was constituted at the beginning of July 2022. The aim of the European initiative is to establish an economic cycle to process inhomogeneous textile waste from different materials and to produce new, high-quality products from it. This project is intended to contribute to achieving the European Union's targets for reducing CO2 emissions by 2030.
Complex textile-containing PET waste such as tyres, tubes or multi-layer composite textiles from the clothing sector have been difficult or impossible to recycle until now. Under the WhiteCycle network, several projects and research approaches will be brought together to address the problem and provide new solutions.
The DITF will adapt an existing PET synthesis process to new types of recycled monomers. The fundamental problem to be overcome is the impurities in the starting material due to its inhomogeneous composition. Together with the project partner Kordsa Teknik Textil A.S. (Turkey), the DITF are developing new synthesis concepts. Their aim is to eliminate possible disadvantages caused by residual contamination of the monomers. This is because not all impurities can be removed despite purification of the monomers before their further processing. The approaches that are taken are demanding.
For example, the type and quantity of additives used must be specifically adapted. These include catalysts, processing aids, nucleating and coupling agents and chain extenders. In this way, it is possible to avoid the negative effects of unknown impurities. This improves the material properties of the recycled plastics, as they are thermally stabilised in the long term, which in turn results in an improvement of the mechanical and rheological properties. The modified process should make it possible for recycled PET (r-PET) to have the same properties as commercial PET.
The consortium partners are pursuing other approaches to produce an improved recycling rate and higher-quality r-PET products: optimised sorting technologies for the sorting of waste are just as much a part of this as enzyme-based treatment of plastics to break them down into monomers in a sustainable way. Ultimately, the high-quality manufacture of new products from the recycled plastics will also help to close the raw material cycle.