EFFECT OF BRASI-COLOR DYE ON UV PROTECTION OF BAMBOO KNITTED FABRICS

Abstract

Even natural dyes have several limitations such as high sensitivity to washing, light, pH, and low color strength and seasonal variation, their use is largely encouraged due to their renewability and multi- functional properties. In this study, 100% bamboo knitted fabric was dyed with Brasi-Color, a dyestuff extracted from brazilwood. The UV-VIS spectra demonstrate the presence of brazilin at pH 4 and of brazilein at pH 7 and 10. The molecular structure of the brazilein is changed at higher pH, due to deprotonation at the OH group of C3. The dyeing parameters and their effect on the dye exhaustion were investigated to optimize the dyeing method and to evaluate the ultraviolet protection factor (UPF). The optimal value was selected based on the highest degree of exhaustion, the dyeing uniformity and the highest color intensity. The maximum degree of exhaustion was achieved for 0.05% dye concentration, pH 7, 90 minutes dyeing at 900C. Even mean UPF, UVA and UVB transmission largely depends on process dyeing parameters, all the fabrics demonstrate an excellent UV protective effect (UPF >50+) and a very low transmission on both UVA and UVB region, being able to protect the human body against the harmful effects of UV rays.

Keywords

• Natural dye
• brazilwood
• UPF
• UV-VIS spectra
• Exhaustion degree