From field to feedstock: Mechanical and chemical behaviour of aged polyethylene fibres from artificial turf

As one of the most widely used polymers, polyethylene (PE) generates large volumes of post-consumer waste. Mechanical recycling is therefore an essential strategy for reducing environmental impacts and preserving resources. Nevertheless, long-term use and repeated processing can promote ageing and degradation processes that may compromise the quality and performance of recycled PE. This study investigates the ageing behaviour and material integrity of recycled linear low-density polyethylene (LLD-PE) fibres obtained from a complex multi-material artificial turf system after an extended service life of 19 years. Extensive material analyses were carried out to identify optical, thermal, mechanical, rheological and chemical changes in used fibres and resulting recycled LLD-PE. Properties were compared with both virgin materials obtained from the replication of the original material recipe as well as with new artificial turf material according to more recent recipes to assess changes and potential use. Results demonstrate that PE properties remain largely unchanged. Ageing-related chemical changes, such as the formation of carbonyl, ether, and hydroxyl groups, were primarily observed on the fibre surface and were mostly no longer detectable in the bulk material after recycling. Contrary to expectations, mechanical, thermal, and rheological properties remain to a large extent unaffected with respect to those of the reference materials. Overall, the findings show that mechanically recycled PE fibres from artificial turf applications retain their structural integrity and functional properties, highlighting the potential of long-lived PE products as valuable feedstock for high-quality recycling applications.