The Study On Preparation And Properties Of Water-soluble Chitosan And Its Application In Fabric Finishing

Chitosan is one of the biologic polymers. It has many good properties such as nontoxicity, antibacterial activity, biological compatibility and biodegradability, which make it get applications in such fields as medicine industry, food industry, chemistry industry, agriculture and textile industry. There is strong hydrogen bonding between molecular chains in its structure and the crystallinity is very high, so it is insoluble in water and most organic solvents, in general, only can soluble in some acidic conditions. This limits its application fields in some degree. Preparation of soluble-chitosan derivatives is one of the important aspects in the studies of chitosan. The modification of chitosan can improve its solubility and increase its application conditions. Also it can benefit to the preparation of all kinds of chitosan derivatives. It will be significant to extend the application. In this paper, we modified chitosan with propylene epoxide and got hydroxypropyl chitosan(HPCTS) with good solubility. The effects of main reaction conditions on the degree of substitution (DS) were discussed. The structure and properties of the products were studied. Also, the application in fabric finishing was studied. The results showed that the DS improved with freeze-alkalization, addition of catalyst, addition of isopropyl alcohol before alkalization, increase of the dosage of propylene epoxide and prolongation of reaction time. And the DS increased first then decreased with the increase of reaction temperature and the concentration of alkali. When the reaction temperature was 60℃and the concentration of alkali was 33%,the reaction was most effective. The 1H NMR and FTIR spectrum of the sample showed the characteristic peaks of HPCTS in C6-OH of chitosan chain. The properties of products HPCTS had been studied. And the results showed that HPCTS had good solubility. When DS≥0.40,the products can dissolve in water directly. It was seen that the crystalline structure changed a lot and the crystallinity decreased obviously from the X-ray spectrum. This was the main reason for its good solubility in water. HPCTS had higher moisture absorption and moisture retention than CTS in the same condition, and these properties improved with the increase of DS. The cotton fabric and the polyester fabric had good antibacterial activity after they were treated with HPCTS. And the antibacterial activity of cotton fabric finished with HPCTS was better than that of fabric finished with CTS, and the antibacterial percent was 94.3%; but the result in polyester fabric was opposite and its antibacterial percent was 74.3%. The fabric can be finished in neutral condition, the finished fabric still had good antibacterial activity. The antibacterial percent of finished cotton fabric was 92.6% and that of finished polyester fabric was 65.7%. It was showed that HPCTS had wider pH regions of application with antibacterial activity than CTS. After washing for ten times, the antibacterial percents was 80% and 56% respectively. Also, the elastic recovery of the finished cotton fabric improved and the loss of strength was low; the whiteness descended slightly .The finished polyester fabric had good antistatic.