UV光引发的丙烯酰胺反相乳液聚合

报道了不透明丙烯酰胺反相乳液体系的UV光引发聚合新方法 .使用普通中压汞灯并辅以适当搅拌 ,UV光引发丙烯酰胺 水 煤油 Span80 +OP 10反相乳液聚合可在 2 0min左右完成 ,所得聚合物分子量达千万 ;聚合过程中不存在恒速期 ,扫描电镜未观察到聚合前后乳胶粒径有数量级的变化 ,表明聚合反应以单体液滴成核为主 .此外 ,考察了光引发剂类型及浓度、单体浓度、乳化剂用量、反应温度等对聚合反应的影响 ,结果表明不同光引发剂的引发活性为Irgacure 2 95 9>(ITX +EDAB) >BDK ,引发剂浓度增加 ,反应速度先增加而后降低 ,存在一最大值 ;单体浓度增加 ,反应速度加快 ,聚合物分子量提高 ;乳化剂用量增加 ,反应速度加快而分子量变化不明显 ;聚合表观活化能为 13 34kJ mol.

INVERSE EMULSION POLYMERIZATION OF ACRYLAMIDE INITIATED BY UV RADIATION

A novel method was developed to polymerize acrylamide in an opaque inverse emulsion system by UV light initiation,which was usually used in a transparent system or semi-transparent system,such as solution systems and micro-emulsion systems.Using 2,2-Dimethoxy-2-phenylacetophenone (DMPA) as an initiator,Span80+OP10 as a blend emulsifier,the inverse emulsion polymerization of acrylamide in kerosene could be completed in about 20?min with exposure under a medium pressure mercury lamp and proper mixing,and the molecular weight of the produced polymer was as high as 10 7.No constant polymerization rate period was observed throughout the whole polymerization process,and there was no dramatic difference between the size of the initial monomer droplets and the size of the final inverse latexes according to scanning electron microscope observation,indicating that the polymerization was nucleated inside the monomer droplets.The influences of the type and concentration of photoinitiator,monomer concentration,emulsifier percentage and reaction temperature on polymerization were investigated.The initiating activity of photoinitiators is in an order of Irgacure 2959 > (ITX+EDAB) > BDK.When the concentration of photoinitiator increases,the reaction rate increases at first,then begins to decrease after the reaction rate reaches a maximum value.Both the reaction rate and the molecular weight increase when the monomer concentration increases.With the increase of the emulsifier percent age the reaction rate increases,while no dramatic change displays in the molecular weight.The overall activation energy of polymerization was measured as 13.34 kJ/mol.