Environment-friendly treatment to reduce photoyellowing and improve UV-blocking of wool

Abstract

Wool products are widely used in people's daily life due to their various excellent properties. However, long-term exposure to solar radiation containing ultraviolet light (UV) can cause severe photoyellowing issues. Also, when used to fabricate apparel, fabrics are expected to own an outstanding UV-blocking feature to protect the skin underneath. In this study, we have developed an eco-friendly treatment to reduce the photoyellowing as well as improve UV-blocking capacity of wool fabrics by introducing para-aminobenzoic acid (PABA) through a microbial transglutaminase (mTGase) mediated acyl transfer reaction in a tris(hydroxymethyl)aminomethane-hydrochloric acid (Tris-HCl) buffer at mild condition. Fluorescent and UV–Vis reflectance spectra proved the successful attachment of PABA on wool fabrics. In addition, relative properties measured after laundering demonstrated the existence of strong covalent bonds, which ensure the stable performance of corresponding fabrics. Moreover, we found that wool fabrics processed by an appropriate concentration of PABA in the enzyme-tris reaction system could effectively resist photoyellowing and exhibit dramatic improvement of UV protection factor (UPF) values. Tensile test results indicated some improvement in the mechanical performance of the treated fabrics after long-term accelerated irradiation. The feasible and effective method developed in current research has great potential to improve the durability and performance of wool products.