Investigation of the chemical recycling of wool fabrics into a novel fibre for commercial application

Abstract

Wool is the most used animal fibre in the fashion industry due to its high quality, longevity, and wide array of applications in fields ranging from comfortable everyday apparel to high-performance sports clothing. The value of wool produced via more environmentally and socially progressive means is increasing, including wool recycled from post-consumer materials. Wool recycling by mechanical means is compatible with open- and closed-loop models, but has issues with fibre length, homogeneity, and large scales; this is in addition to the common issues of any material recycling such as collection and sorting. An alternative technique is chemical recycling which is currently used for the treatment of synthetic polymeric materials at various scales. There is hope that this technique can be adapted to enhance the recycling of wool and may serve complementary to the current mechanical methods. This project considers the preliminary chemical recycling of wool keratin to make textile fibres. Commercial wool offcuts were successfully dissolved by a reduction process to give solutions of ~ 11.3 weight % (wt%) keratin, showing efficiency of approx. 75.6 %. This keratin solution was blended with 2-hydroethoxy cellulose (HEC) and polyvinyl alcohol (PVOH), and the resultant blends were used to make films and to create filaments via a laboratory scale wet-spinning system. The filaments were successfully cross-linked with glutaraldehyde (GA) and 4,4′-methylenebis- (phenyl isocyanate) (MDI) to impart useful tensile properties. A variety of filaments were found to have tenacities at break above 0.5448 cN/Tex (5 g/denier). The tenacities fell within the range of other fibres on the market, but the extension at break was far below these, suggesting difficulty in application to the textiles market. The process was analysed at different stages with Fourier Transform Infrared spectroscopy (FTIR), Ultraviolet Visible Light spectroscopy (UV-Vis), and SDS polyacrylamide gel electrophoresis (SDS-PAGE). The surface morphology of the material was assessed via Scanning Electron Microscopy (SEM) and the tenacity was tested using Instron apparatus. Although the different stages of the outlined process have not been optimised due to time constraints, the project serves as a springboard for further work on lab-scale recovery of wool keratin from waste fabric, specifically for re-use in the textiles industry.