Abstract:

In the present study, corn starch was etherified with N-(2, 3-epoxy propyl) trimethyl ammonium chloride (GTA) under the catalysis of sodium hydroxide and high-substituted cationic starches were obtained. To achieve an optimal compromise between high degree of substitution (DS) and high reaction efficiency, orthogonal array design was used to investigate reaction temperature and time, water content in reaction system and addition amount of sodium hydroxide affecting highsubstituted cationic starch preparation. Meanwhile, products with different DS obtained were structurally characterized by infrared, polarization and X-ray spectroscopies. Results showed that the contribution of the above parameters to the DS of corn starch followed the decreasing order: reaction time ＞ reaction temperature ＞ water content in reaction system ＞ addition amount of sodium hydroxide. The reaction for 4 h at 80 ℃ in a reaction system consisting of 10 g of starch, 1.5 g of GTA and 0.2 g of sodium hydroxide and having 24% water content resulted in a DS of 0.105. As DS increased, the transparency and solubility of catonic corn starch exhibited an increase. Infrared, polarization and X-ray spectroscopic analyses demonstrated some changes in the structure of corn starch due to substitution.

Key words: cationic starch, degree of substitution (DS), N-(2, 3-epoxy propyl) trimethyl ammonium chloride (GTA), structural characterization