Research On Dyeing And Finishing Properties Of Viscose/Chitin Bicomponent Fiber

Viscose/chitin bicomponent (viscose/CH) fiber is a new kind of modified viscose fibercombining the advantages of viscose fiber and chitin polymer. It is necessary to understandthe dyeing and finishing properties of this bicomponent fiber. With the aim of betterunderstanding the adsorption mechanisms and dyeing properties of various dyes on thisbicomponent fiber, two direct dyes, three reactive dyes and one natural dye (lac dye) werechosen to dye this fiber. The related research was hoped to provide help for the dyers tocontrol the dyeing process and select the employed dyes. The main conclusions were asfellows:(a) The equilibrium adsorption isotherms of direct dyes and natural lac dye onviscose/CH fiber could be best fitted by the Langmuir-Nernst model, indicating that thespecial-site and non-special site interactions occurred between dyes and fibers. Thespecial-site interaction originated from the adsorption of anionic dyes by the partiallydeacetylated chitin component in viscose/CH fiber. The contribution of Langmuiradsorption to total adsorption depended on pH, dye concentration, and dye category. Forthe adsorption of lac dye, the Langmuir adsorption was predominant in total adsorption.(b) Direct dyes showed faster adsorption rates, higher adsorption capability, and betterbuilding-up properties and color fastness to washing on viscose/CH fiber than on viscosefiber. Viscose/chitin fiber showed great dye adsorption capability even at a low salt dosage.Additionally, the difference between the dye adsorption capability of viscose/CH andviscose fiber depended on dye category.(c) Reactive dyes showed faster adsorption rates and higher adsorption capability onviscose/CH fiber than on viscose fiber. The difference in the uptake and fixation of reactivedyes on viscose/CH and viscose fibers would be amplified in the case of low to mediumdosage of dyes, low dyeing temperature, no addition of alkali, and the use of low molecular weight dyes. The uptake and fixation of reactive dyes on viscose/CH fiber were lessdependent on dyeing temperature than those on viscose fiber. The reactive dyeing ofviscose/CH loose fibers only needed a low dosage of alkali.(d) The quantity of the uptake of lac dye by viscose/CH fiber had almost an increasetrend linearly with increasing pH of dyebath, and the selection of low pH was preferablefor lac dyeing. The quantity of lac dye adsorption on viscose/CH fiber was very closer tothat on silk fiber, but much lower than that on wool fiber. The wash color fastness of lacdye on viscose/CH fiber was superior to that on silk, and inferior to that that on wool. Thedyed viscose/CH fiber with lac dye showed good antioxidant activity, and antibacterialactivity against Staphylococcus aureus and Escherichia coli, and accordingly it can be usedfor developing functional textiles.