Bicomponent regenerated cellulose fibres: retaining the colour from waste cotton textiles

Bicomponent regenerated cellulose fibres (bRCF) have been created in a core-shell configuration from waste textiles. Textile dyeing and colouration is known to be a major contributor to the environmental impact of producing textiles and this needs to be addressed for textiles to become more sustainable. Coloration of the bRCF here was achieved by utilizing coloured textile waste in the shell component whilst using white cotton waste in the core. The shell and core extrusion speed and thus shell and core diameter were varied and optimised for colour strength. The optimised bRCF was made up of 49.6% dyed material yet was able to achieve the same colour strength as the single component regenerated cellulose fibre (RCF). The potential benefit of this approach is the reduced amount of coloured material required to colour these recycled fibres without any sacrifice in colour intensity. The mechanical properties of the bRCF were similar to the single component RCF with tensile strengths of 115-116 MPa and maximum elongations of 15.2-17.5%. The morphology of the bRCF was similar to single component regenerated cellulose fibres, while optical micrographs showed the discrete coloured core-shell structure of the bRCF. This manuscript details the fibre properties, dye savings and spinning approach.