Continuous High-Content Keratin Fibers with Balanced Properties Derived from Wool Waste

The full utilization of discarded wool for the preparation of continuous recycled keratin fibers has been a challenging subject. The key issue lies in how to utilize wool keratin as much as possible without damaging the main chain structure of the protein molecules. Based on small molecule simulation reactions, the authors find out that disulfide bonds, the only cross-linking bonds in keratin, can be effectively broken by starch-derived dithiothreitol, and the resultant keratin can be well separated by the cosmetic ingredient sodium dodecyl sulfate, which forms micelles that stabilize the keratin solution. Accordingly, the traditional strong hydrogen-bond breakers like urea and LiBr can no longer be used, which helps to protect the integrity of keratin. The resultant fully dissolved, highly concentrated keratin solution (keratin content = 18 wt %) is directly applied for wet spinning. To toughen and strengthen the envisaged keratin fibers, a few hydroxypropyl cellulose and glutaraldehyde and 4,4′-methylenebis(phenyl isocyanate) are incorporated. Eventually, the regenerated continuous fibers with keratin content as high as 90 wt % offer a combination of properties similar to natural wool.