流变仪旋转叶片法在自由基聚合反应中的应用研究Ⅲ:有机羧酸对丙烯酰胺自由基聚合的阻聚作用

Study on the Application of Vane Rheometer in the Free-Radical Polymerization Part Ⅲ:the Inhibition of Organic Acid on the Gelation of Acrylamide

使用装备自制的四叶片旋转叶片的应力控制流变仪研究过硫酸铵和四甲基乙二胺氧化还原体系作为引发体系引发丙烯酰胺自由基聚合过程的模量曲线,交联剂为N,N’-亚甲基双丙烯酰胺。测试了添加柠檬酸、聚丙烯酸和乙酸的丙烯酰胺聚合反应的空闲时间(idle time),研究了有机羧酸浓度、体系pH以及缓冲溶液对丙烯酰胺聚合体系的影响,发现在较低pH(小于4.5)的体系中有机羧酸对丙烯酰胺的自由基聚合反应存在阻聚或缓聚作用,并且发现可以调节体系的pH到较高值(10.5)可使被阻聚的自由基被重新激活,激活后的聚合反应的idle time不受有机羧酸浓度和阻聚时间的影响。

A new technique ,rheological method was used to study the cross-linking polymerization of acrylamide and N,N＇- menthylene-bis-acrylamide initiated by ammonium persulfate and N,N,N＇,N＇-tetramethylethylenediamine redox initiator system .The effect of organic acid on idle time of polymerization was investigated by the vane method. The organic acids were found to be inhibition action on the polymerization of AM at lower pH value while this phenomenon was not found at higher pH value. The free radicals or growing chain radicals inhibited at lower pH value could be reactivated by adjusting pH value to higher （10.5）. And the polymerization inhibited for hours with 0.28wt% and 0.56wt% citric acid could be resumed and reacted at almost same time about 27.5 minutes.