Preparation Of Protein Cotton Fiber (Cottons) And Its Stucture And Properties

Study on modification of cotton fiber is a hotspot problem on the field of textile fibers research at present, however protein modification of cotton fiber is seldom studied. Based on this idea, the topic of protein modification is deeply discussed. In this paper, selective oxidation technique used for cotton fiber makes its two vicinal hydroxyl groups in cellulose chain unit oxidized to aldehyde groups. By using the activity of aldehyde groups, the oxidized cotton fiber has the ability to crosslink directly with the biological protein. On this basis, protein cotton fibers are prepared by sericin and wool keratin treating cotton fiber. On the whole technical process, there is no chemical crosslinking reagent. Protein cotton fiber is pure natural material and the preparation technology is practical and reasonable, which can meet people's needs of about greenness and environment protection.Two kinds of oxidized cotton are prepared by different process, which are dialdehyde cotton fiber/fabric (cotton directly treated with sodium periodate, and is named DCF) and dialdehyde basifying cotton fiber/fabric (cotton treated with alkali pretreatment and then treated with sodium periodate, and is named DBCF). It confirms that the aldehyde groups in glucose units of cotton fiber are created by structural analysis and determinations of aldehyde group. The results show that with increasing oxidation degree, the thermal stability and the crystallinity of cotton fiber decrease gradually, and the crystallinity of cotton fiber oxidized severely changes from celluloseⅠt o amorphism. Raising the degree of oxidation decreases the strength of cotton yarn while enhances the aldehyde groups content of cotton fiber, and negative linear correlation is found between them.In order to improve oxidation effectiveness and enhance the aldehyde production quantity of the oxidized cotton fiber, it is adopted that the alkali treatment technique in pre-activating for cotton fiber before selective oxidation treatment. According to comparison, the results show that cellulose crystalline structure are transformed from celluloseⅠt oⅡgradually and its crystallinity decreases constantly after alkali pretreatment with increasing concentration, which can improve the reactivity of cotton fiber with sodium periodate. Under the same oxidation condition, the aldehyde groups content of DBCF is superior obviously to that of DCF, and their strength is close.In this paper, keratin solution is prepared by using NaOH and H2O2 to dissolve the wool, and the product is applied to the modification of cottons. Dialdehyde cotton fiber/fabric, dialdehyde basifying cotton fiber/fabric and cotton fiber/fabric are modified with sericin and self-made keratin. The results show that the weight gain of coated oxidized cotton is bigger than that of native cotton. Through analysis of the structure, it is suggested that the aldehyde groups of cotton fiber can directly crosslink with amide in molecule of protein, however no covalent bonds are found between protein and native cotton. Alkali pretreatment can improve further the grafting quantity of protein onto oxidized cotton, which can make the surface of fiber smoother. Comprehensive consideration to the weight gain and mechanical properties, treatment process for sericin coating cotton: concentration of sericin solution 3-5wt%, pH value about 6, temperature at 50℃and time at 1.5h; treatment process for keratin coating cotton: concentration of keratin solution 4-5wt%, pH value about 6, temperature at 50℃and time at 2h. Cotton fabric coated with sericin or keratin has smooth hand feel and liberality. Compared with native cotton fabric, wrinkle resistance, water absorbency and anti-ultraviolet property of protein cotton fabric are promoted efficiently. Among them, DBCF coated protein has better performance.