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

Authors: CHEN, NUSHENG - Oak Ridge Institute For Science And Education (ORISE); Liu, Cheng Kung; Brown, Eleanor - Ellie; Latona, Nicholas - Nick

Submitted to: Polymer Degradation and Stability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2020
Publication Date: 8/7/2020
Publication URL: https://handle.nal.usda.gov/10113/7067541
Citation: Chen, N., Liu, C., Brown, E.M., Latona, N.P. 2020. Environment-friendly treatment to reduce photoyellowing and improve UV-blocking of wool. Polymer Degradation and Stability. https://doi.org/10.1016/j.polymdegradstab.2020.109319.
DOI: https://doi.org/10.1016/j.polymdegradstab.2020.109319

Interpretive Summary: Wool is the textile fibers obtained from sheep or similar animals. Due to its unique properties, such as resiliency, excellent heat retention, and flame retardancy, people have widely used wool products for a long history. However, the long-term exposure of wool to sunlight could cause yellowing and degradation issues. In order to improve the stability of wool products under the sun exposure, we have developed a novel, environment-friendly method to treat wool. In this method, we successfully introduced a relatively safe, ultraviolet-absorbing molecule to wool fabrics through an enzyme-mediated reaction. The reaction could create a strong binding between molecules and fabrics, so prolonged protection of fabrics was achieved. After treatment, the yellowing of wool fabrics was effectively slowed down, and the penetration of harmful ultraviolet light could be primarily blocked. We also observed the slower degradation trend through scanning electron microscope images and mechanical properties. The proposed treatment using bio-based enzymes may pave a new road to improving the photostability of wool products, which will further enhance their marketability.

Technical 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 possess an outstanding UV-blocking feature to protect the skin underneath. In this study, we developed an eco-friendly treatment to reduce the photoyellowing as well as improved 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 the mild condition. Fluorescent and UV-Vis reflectance spectra proved the successful attachment of PABA on wool fabrics. The further durability test demonstrated the existence of strong covalent bonds, which ensure the stable performance of corresponding fabrics. Moreover, observations showed 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.