反相乳液五元体系淀粉接枝共聚反应动力学

Kinetics of graft copolymerization of acrylamide onto cassava starch in a five-component system of inverse emulsion

研究了在淀粉/单体/乳化剂/油/水五元反相乳液体系中引发淀粉和丙烯酰胺接枝共聚反应的动力学,考察了引发剂和乳化剂浓度、单体和淀粉浓度、反应温度等因素对表观聚合速率的影响.结果表明:在本实验考察范围内单体浓度和淀粉浓度对聚合速率影响明显,聚合过程中快速链终止和慢速链终止反应同时存在,动力学关系式为:Rp∝[I]0.93[M]1.28[St]1.47[E]0.61,聚合速率随体系温度的升高而加快,在35～55℃范围内,聚合反应的表观活化能为82.01kJ·mol-1.

The kinetics of graft copolymerization in a five component system of inverse emulsion, starch/ monomer/emulsifier/water/oil, was investigated with cassava starch and acrylamide （AM） as the raw material, ammonium persulfate as the initiator and a mixture of two kinds of surfactants （Span-80 and OP-4） as the emulsifier. The rate orders of graft copolymerization with respect to the concentration of initiator, monomer, starch and emulsifier were determined. In the polymerization process, termination of fast chain and termination of slow chain existed at the same time. The effect of the concentration of the individual components in the polymerization system on conversion were investigated. The results showed that the dependence of the polymerization rate Rp on the concentration of components in the polymerization system could be expressed for all four components by the following equation. Rp∝[I]^0.93[M]^1.28[St]^1.47[E]^0.61~. The overall activation energy for the polymerization process was 82.01 kJ·mol^-1 at 35-55℃. Based on the experimental results, some aspects of the polymerization mechanism were discussed.