Chemical modification of rice starch via its reaction with acrylamide

Rice starch was carbamoyl ethylated via its reaction with acrylamide in presence of sodium hydroxide under a variety of conditions. Variables included the concentration of acrylamide, the reaction temperature and the preparation medium. It was found that the extent of the reaction increases by increasing the acrylamide concentration. The temperature plays a dominant role in the extent of the reaction. Carbamoyl ethylated starches are water soluble and can be precipitated by ethyl alcohol. Printing pastes thickened with carbamoyl ethyl starch samples are characterized by non‐Newtonian thixotropic behaviour. At a constant rate of shear, the values of the apparent viscosity increase as the nitrogen content of the product increases. Furthermore, increasing the reaction temperature is accompanied by a substantial decrease in the apparent viscosity at a constant rate of shear.