Property Recovery in Thermo-Mechanically Recycled Polyester Textiles via Virgin Material Addition and PBO Chain Extension

The textile industry generates tens of millions of tonnes of textile waste annually, a large proportion of which comprises poly(ethylene terephthalate) (PET) fibres. Although recycled PET textiles are commercially available, these materials are almost exclusively obtained from post-consumer plastic bottle waste rather than textile waste. Thermo-mechanical textile-to-textile (T2T) recycling is possible; however, its use at industrial scale remains limited, partly due to reductions in polymer quality during reprocessing. This study investigates the changes in PET polymer properties resulting from thermo-mechanical recycling of real-world textile waste samples at pilot scale, particularly decreases in polymer viscosity. Two approaches for improving the quality of the recycled PET were trialled: the addition of the chain extender 1,3-phenylene-bis-oxazoline (PBO) and the addition of virgin PET. Both methods demonstrated improvements in the properties of recycled PET to some degree, achieving levels suitable for further textile applications. However, the addition of virgin PET provided a more consistent and reliable means of restoring polymer quality. These findings demonstrate the potential of thermo-mechanical T2T recycling as a method for decreasing the amount of polyester textile waste sent to landfill and incineration.