Recycling keratin polypeptides for anti-felting treatment of wool based on L-cysteine pretreatment

Abstract

Abstract An anti-felting finishing process based on recycling waste wool material was proposed. Wool fabric was pretreated with L-cysteine and then treated with the keratin polypeptides, extracted by protease from the waste wool. And then, wool fabric was treated with glycerol diglycidyl ether as cross-linking agent for a durable anti-felting effect. The padded-out keratin polypeptides solution was collected, replenished with a small amount of fresh keratin polypeptides and recycled for 10 times. An excellent anti-felting performance was still achieved when wool fabric was treated with the 10th-recycled keratin polypeptides. The protein concentration of 10th-recycled keratin polypeptides was almost unchanged, but the weight-average molecular weight decreased. There was no significant difference on the modified surfaces between the wool fabrics treated with recycled keratin polypeptides and those with the fresh ones. Compared with the control, there was an improvement in whiteness, softness, dyeability, hydrophilicity and an acceptable loss in weight (about 1%) and in strength (about 6.1% in warp direction) after fixation of the extracted keratin polypeptides onto the fabrics. The modification mechanism was confirmed by scanning electron microscopy, Raman spectra and X-ray photoelectron spectroscopy analysis of treated wool fabric that L-cysteine can erode the fiber surface, generating more reactive groups, and then keratin polypeptides can easily cross-linked onto the fiber surface by glycerol diglycidyl ether or covered the fiber surface.