Production of uv-sensitive textile fibres with the Ioncell® technology

Abstract

Ioncell® technology is a novel way of producing sustainable textiles, which is based on the production of cellulose-based fibres and yarns using ionic liquids as a green solvent. This technology enables the incorporation of functionalities directly into the fibre body while maintaining high mechanical properties, which opens avenues for smart textiles production. SensoGlow® is a non-toxic and tuneable mineral, which reacts to UV irradiation through a reversible colour change, i.e. photochromism. In this thesis, an environmentally friendly way of producing UV sensing textiles by incorporating SensoGlow® or a commercial photochromic dye into Ioncell® fibres was demonstrated.

Incorporating additives into a cellulose dope while maintaining good spinnability is challenging, which is why it was crucial to develop a method that could disperse SensoGlow® particles homogeneously in ionic liquid and cellulose. In this work, both mechanical treatments (e.g. sonication) and dispersants (e.g. nanocellulose) were applied to improve the dispersion of SensoGlow®. After achieving a cellulose dope with evenly distributed SensoGlow® or dye, UV-sensitive fibres were successfully spun using a monofilament spinning unit. Lastly, multifilament spinning was used to produce SensoGlow® incorporated fibres, which were spun into yarn and knitted into a demo fabric.

The results from the tensile testing showed that the incorporation of additives weakens the mechanical strength of fibres, but even with 5 wt% additive the tensile strength of fibres was similar to the commercial TencelTM. The results from the reflectance measurements indicated that the optical response of fibres is dependent on the additive concentration. Additionally, it was shown that 3.5% SensoGlow® fibres could be spun into yarn with similar tensile strength as TencelTM yarn and similar elongation as cotton yarn. Finally, 15 cm x 15 cm demo fabrics were knitted to demonstrate that 1) fabric with incorporated SensoGlow® can be used to detect UV exposure and 2) the fabric maintains functionality in normal wear.

There is still room to optimize the process and enhance the fabric response to UV. However, as a proof-of-concept, this thesis implies that SensoGlow® can be incorporated into MMCFs to produce smart textiles that could be used to detect the UV dosage of the user.