Discriminating the viscoelastic properties of cellulose textile fibers for recycling

Funding Information: Yingfeng Wang and Teemu Airaksinen from Aalto University, School of Chemical Engineering are gratefully acknowledged for measuring the intrinsic viscosity of the cotton bed linens and roll towels. This work was financially supported by the Strategic Research Council of the Academy of Finland under grant agreement no. 327296 – the FINIX project (finix.aalto.fi). The viscoelastic properties of cellulose fibers play an important role in chemical recycling of textiles. Here we discriminated the intrinsic viscosity of cotton roll towels and bed linens using near-infrared imaging spectroscopy and supervised pattern recognition. The classification results showed training and test set accuracies of 84–97% and indicated that the relevant spectral features were related to water, cellulose, and cellulose crystallinity. We hypothesized that the decreasing intrinsic viscosity of cotton was associated with changes in cellulose crystallinity and water adsorption, which was supported by additional X-ray and sorption measurements. These results are important as they indicate the potential to non-invasively estimate the degree of polymerization and the suitability of different cotton materials for chemical recycling. We propose that changes in the degree of polymerization and cellulose crystallinity could be used as an indicator of the chemical quality of cellulose fibers, which would have wider impacts for textile recycling.