Studies On The Semi-dry Preparation And Prorerty Of Cationic Starch With Low Degree Of Substitution

The nitrogen atoms of cationic starch had the positive charges. The cationic starch had characteristics of low pasting temperature, high transparency, weak retrogradation and good solubility. The cationic starch got extensive application in the paper industry, textile industry and other fields. The Semi-dry Preparation and granules and paste properties of cationic starch with low degree of substitution was studied. The main results were as follows:1 The technological course and effect of reaction factors on reaction efficiency was established.By using quadratic general rotary experiment design , the regression equation was established. The optimum technology parameter of normal and high temperature were confirmed as follows : the ratio of CHPTMA and NaOH being 1.85, the water content being set as 20.5 %, the reaction temperature being at 60℃, 4.5h for the reaction time, the reaction efficiency is up to 89.48% and the degree of substitution was 0.034; At 25℃, the ratio of CHPTMA and NaOH being 2.1, the water content being set as 19.6 %, the reaction time being 2d , the reaction efficiency is up to 88.06% and the degree of substitution was 0.033.2 The reaction efficiency preparing cationic starch using various starchs was different. The potato starch was better than corn starch. The reaction efficiency of sweet potato starch was the highest, being up to 99.02%.3 The surface shape and crystal properties of semi-dry prepared cationic starch granule with low degree of substitution were less changed. Compared with native starch, the transparency of cationic starchs with low degree of substitution was increased. The transparency of cationic starch reacting at 60℃was higher than that reacting at at 25℃except the cassava starch. The transparency of cationic starch neutralizing by the hydrochloric acid and acetic acid was higher than that neutralizing by the citric acid and adipic acid.The transparency of cationic starch of potato starchs was higher than that of cereal starch. 4 The cationizing influenced differently on the various starchs. Comparing with native starch , the shear stability of cationic starch reacting at 25℃of corn, waxy maize starch, murphy, cassava, sweet potato were decreased. The shear stability of cationic starch reacting at 60℃murphy, sweet potato were increased but that of other three starch were decreased. Comparing with sample reacting at 25℃, the apparent viscosity of sample reacting at 60℃was lower and its shear stability was better. The apparent viscosity of cationic stach neutralizing by citric acid was lowest and its shear stability was best. The ishear stability of the cationic starchs of waxy maize starch was worse, and others was better.5 The effect of the cationizing on pasting properties of native starch was complicated.Compared with the native starch , the pasting temperature of cationic starch were all lower but other pasting properties changed complicatedly. Compared with sample reacting at 25℃, other pasting properties of cationic starch reacting at 60℃were lower except pasting temperature. The effect of the different acid on pasting properties of cationic starch was complicated. The pasting properties of cationic starch prepared with the five native starchs had the significant differences. In real application, the kind of acid and native starch were choosed according to requirement.