Study On Dyeing Properties Of Natural Dyes On Chitosan Fibers

Chitosan fiber is biomass regeneration fiber which is made by a natural product deacetylated chitin in wet spinning process preparation.It has good biocompatibility and degradation.It is friendly to environment.The study of natural dyes dyeing on the chitosan fiber has great significance for the development of eco-textiles.This study majors on the basic properties of chitosan fibers and the dyeing performance and dyeing process of natural dyes on chitosan fibers.The morphology and chemical structure of chitosan fibers were characterized by electron microscopy and infrared spectroscopy.The cross section of the fiber was solid and the shape was round.The infrared spectroscopy showed that a multi-absorption peak at which the absorption peak of the-OH stretching vibration and the stretching vibration absorption peak of-NH are overlapped with each other at about 3423 cm^-1.(?_C=O)appeared at 1652cm^-1,and the absorption peak of?_N-H appeared at 1599cm^-1,which indicated that the chitosan fiber had higher degree of deacetylation.The crystal structure of chitosan fibers was analyzed by X-ray diffraction spectroscopy,and compared with silk and viscose fibers.The results showed that chitosan fibers have the same difference between crystalline and amorphous phases as silk and viscose fibers.The crystallinity of Chitosan fiber is 32.43%.Compared with silk and viscose fiber the crystallinity of Chitosan fiber is a little smaller.The effect of different acid agents on the properties of chitosan fibers was tested in order to select the acid agent which is suitable for acid dyeing bath.The results of experiments showed that the order of effect on chitosan fiber was as follows:malic acid>citric acid>acetic acid>sulfuric acid.The sulfuric acid was chosed to be the agent to adjust pH of acidic dyeing bath finally.The adsorption kinetics of chestnut shell pigment,chrysanthemum yellow pigment and carmenum red pigment on chitosan fiber were studied.The result showed that the equilibrium adsorption capacity of the three natural dyes on chitosan fibers increased when the temperature increased.The adsorption models of the three dyes on chitosan fibers are in accordance with the equation of quasi-second adsorption kinetic.It can be concluded that the adsorption of three kinds of natural dyes on chitosan fibers is mainly based on chemical adsorption of ion bonds,and there are also some Van der Waals forces.The factors affecting the direct dyeing of six kinds of natural dyes on chitosan fiber were studied,and the optimum dyeing process was obtained.The fastness of chitosan fibers dyed by natural pigments was tested.The results showed that the light fastness of shellac pigment,carmine red pigment and chestnut shell pigment could reach grade 3 and above,and the water fastness of Chitosan fibers dyed by pigments other than chestnut shell is poor.In order to improve the dyeing fastness,the effect of metal ion mordant on the dyeing properties of natural dyes on chitosan fibers was studied.The results showed that mordant treatment could improve the K/S value of chitosan fibers,and the pre-media dyeing process is the best.The effect of iron ion on the shade of the fabric was relatively large,the brightness decreased significantly,aluminum ion effect is smaller;the test of color fastness showed that the light fastness of six kinds of dyes can reach more than level 3 after mordant.The soap fastness of gardenia yellow pigment,safflower yellow can reach more than level 4,in line with the requirements.After the media dyeing process to improve the color fastness is generally better than the pre-media dyeing and bath with the media dyeing process.