机械活化淀粉反相乳液五元体系的接枝共聚反应动力学

Kinetics of Graft Co-Polymerization of Acrylamide onto Mechanically-Activated Starch in Five-Component Inverse Emulsion

以机械活化淀粉为接枝母体,研究了在机械活化淀粉/单体(AM)/乳化剂/油/水五元反相乳液体系中引发机械活化淀粉接枝丙烯酰胺共聚反应的动力学。分别考察了引发剂浓度、单体浓度、淀粉乳浓度和乳化剂浓度等对接枝量和接枝共聚速率(R g)的影响。结果表明,在本实验考察范围内的动力学关系式为R g∞[mSt]1.24[I]0.76[M]1.54[E]0.33,淀粉与丙烯酰胺的接枝共聚速率随体系温度升高而加快,淀粉乳浓度和单体浓度对接枝共聚速率影响显著,在45℃～60℃范围内,接枝共聚反应链增长步骤的活化能为34.85 kJ/mol。

The kinetics of graft co-polymerization in the five-component inverse em41sion system, mechanicallyactivated starch/monomer/emulsifier/oil/water, were investigated using ammonium persulfate as the initiator and the mixture of Span 80/Tween 80 as the emulsifier. The effects of concentrations of initiator, monomer, starch and emulsifier on Gm and the rate orders of graft co-polymerization were determined. The results show that the dependence of the graft co-polymerization rate Rg on the components concentration in the polymerization system can be expressed for all four components by the following equation RT∞ [mSt]^1.24[I]^0.76[M]^1.54[E]^0.33. The graft copolymerization rate of acrylamide onto starch increases with the increasing of temperature. The influences of concentrations of starch and monomer on the rate orders of graft co-polymerization are predominant. The activation energy of chain propagation for the polymerization process is 34.85 kJ/mol within 45℃～60℃.