CHEMICAL MODIFICATION FOR RESISTANCE TO PHOTO-OXIDATIVE DEGRADATION AND IMPROVED BLEACHING AND COLOR FASTNESS PROPERTIES OF HEMP FIBER

The objective of the research has been to overcome some inherent drawbacks of hemp fiber via chemical modification, which is a vital issue in using it as a textile fiber like cotton. Hemp fiber was modified with treatment liquor (mixture of sulfurous acid and sodium hydroxide) in aqueous medium to remove lignin. The effects of the treatment liquor concentration, fiber to liquor ratio, reaction time and temperature on the percent lignin extracted from hemp fiber were studied. Modified hemp fibers (MHF) were bleached in an alkaline pH aqueous medium with hydrogen peroxide. The process significantly improved lignin removal, bleaching and color fastness. In fact, the whiteness index of bleached MHF was significantly higher than that of bleached raw hemp, but its tensile strength was slightly affected. The photo-oxidative degradation of hemp fiber was 70% lower than that of unmodified (raw) hemp fiber and almost like that of cotton yarn. The color fastness properties of dyed bleached modified hemp fiber were significantly better than those of dyed bleached unmodified hemp fiber and close to those of dyed bleached cotton yarn.