Przemysl Chemiczny, Vol.82, No.8-9, 1157-1160, 2003
High-viscosity modified starch
Di-starch phosphate, 5 g in 50 mL H2O at 30degreesC, alkalized with 0.75 g NaOH (in 20 mL H2O), was carbarnoylethylated 6 h with 2.5 g acrylamide (in 20 mL H2O) at 45degreesC, degree of substitution, 0.207 (max). The mixture was neutralized at 25degreesC to pH 7 with aq. 10% HCl; the product was precipitated with 1000 mL MeOH and dried at 75-80degreesC. At NaOH > 0.80 g, the degree of substitution tell owing to hydrolysis of amide groups to -COOH, and NH, was released. At shear rates of 5-10 s(-1), the (25degreesC, aq. 5%) viscosities of the products modified 2.5 h and 6 h were resp. 24 and 16 Pa.s vs. the 8 Pa.s of the starting di-starch phosphate. Product structure was confirmed by elementary analysis and FTIR.