高取代度阳离子淀粉合成反应动力学研究

Study on the Synthesizing Kinetics of Cationic Starch with High Degree of Substitution

研究了半干法制备高取代度阳离子淀粉的反应动力学过程,讨论了不同温度、反应物料配比、催化剂用量等反应条件对淀粉醚化反应速率的影响．结果表明,提高反应温度,反应速率明显加快,反应程度与体系黏度的变化并无直接关系,淀粉阳离子化反应符合二级动力学的反应机理,阳离子醚化反应的表观活化能E_(?)=76．5 kJ/mol．醚化反应速率随着体系中醚化剂和催化剂浓度的增加而升高,但副反应也逐渐加剧．

The synthesizing kinetics of cationic starch with high degree of substitution by half-dry process has been studied according to the degree of reaction or degree of substitution （DS）. The influences of reaction conditions such as temperature, ratio of reacting mass and content of catalyst on the reaction rate have been discussed. The results show that the degree of reaction does not correlate directly with the viscosity of the reacting system. The reaction rate increases dramatically with the rising of reaction temperature,and the reactions follow the second-order reaction mechanism. The apparent activation energy achieved is 76.5 kJ/mol. The reaction rate also increases at higher concentration of ETA and catalyst while the side reactions aggravate gradually.