Effects of gallic acid grafted chitosan on improving light fastness of cotton fabric dyed with gardenia yellow

Antioxidants can inhibit the photofading of natural dyes. However, their effects on improving the light fastness of fabrics dyed with natural dyes are still limited since no stable covalent bonds formed between their molecules and the substrate in the conventional dipping and padding method. In this study, one antioxidant, gallic acid, was grafted to chitosan via the redox reaction between ascorbic acid and hydrogen peroxide. The grafted chitosan was then cross-linked onto cotton fabric dyed with gardenia yellow. Results of colour change caused by the exposure of treated fabric to simulated sunlight irradiation show that gallic acid grafted chitosan (GA-g-CTS) inhibited photofading of gardenia yellow on cotton. Results from handle test show that although the softness of cotton fabric cross-linked with GA-g-CTS slightly deteriorated, the overall handle of the treated fabric was not distinctly affected.