Study On The Preparation And Application Of Cationic Starch With High Degree Of Substitution

The cationic starches with high degree of substitution were prepared and many affecting factors, such as reactant, reagent, catalyst and reaction conditions, were discussed in detail. At the same time, the application properties of the cationic starches were investigated. The cationic starches with high degree of substitution(DS) of 0.1 0.99 were prepared by modified process via reacting starch with glycidyl trimethyl ammonium chloride in the presence of new catalyst BZ- 1. The different factors, which included the amount of new catalyst BZ- 1, reaction duration and temperature and the type and amount of solvent, affecting the reaction efficiency and DS were studied. Then, the optimal conditions for synthesizing the cationic starches with high DS were determined. This process improved the space-time yield, because the cationic reaction can be made in 80% high solid content. The cationization process was so efficient that it needed only a little of solvent, consumed the lowest energy and gave the most reaction efficiency. In this process, the special mixer, squeezer, was no need and a satisfactory result can be obtained by using the common stirrer. Furthermore, it should be mentioned that the stirrer was not used when the reaction mixture was heated. The reaction efficiency of preparing cationic starches with DS of 0.1- 0.56 reached 96.3 7.5%, whereas that of 0.56---0.989 reached 87.56.1%. The the preparation of cationic starches with DS of 0.56 0.989 in -80% high solid content was not reported by others. The crosslinked cationic starches with DS of 0.1 .95 were prepared by the same process. The reaction efficiency of preparing the crosslinked cationic starches with DS of 0.5 1 0.95 reached 85 79.3%. The the preparation of cationic starches with DS of 0.56 0.989 in 80% high solid content was not reported by others. The relationship between viscosity, DS and reaction conditions was investigated in greater detail and the cationic starches with high viscosity and DS were obtained. The results showed that the viscosity of cationic starches was closely correlated to reaction temperature, reaction duration and the amount of catalyst and water in reaction mixtures. The cationic starches prepared above were used in salt-free dyeing. The results showed that the dyeing effects were related to the DS and concentration of cationic starches and the adsorption and fixation of reactive dyes on the cotton treated with the cationic starches were higher than that of traditional dyeing. The dyed cotton had the wash fastness of 4, light fastness of 3 and rub fastness of 4. It was the fist time to use the cationic starches in salt-free dying and the result was helpful for the industrial application. The crosslinked cationic starches with high DS prepared above were used for treating dyeing wastewater. The results meant that the crosslinked cationic starches were usable in wide range of pH and the decoloring effect was related to the DS of the crosslinked cationic starches. Particularly, the lower the pH, the better the decoloring effect and the higher the DS, the better the decoloring effect. The adsorption of the crosslinked cationic starches with DS of 0.95 for acid red G, reactive red X-3B and direct ice yellow G was 1.38mg/mg, 1.55mg/mg and I .80mg/mg respectively. Finally, the flocculation test was conducted with the cationic starches with high DS and resulted that they could be used in wide pH range. The higher the DS, the wider the pH...