MMA-EA-AA无皂乳液聚合中粒径及粒径分布的控制

系统研究了MMA EA AA三元无皂乳液聚合体系中各种因素对乳胶粒大小及分布的影响 ,制得了单分散、粒径在 30 0～ 6 0 0nm可控聚合物乳胶粒 .结果表明 ,在过硫酸铵用量一定的条件下 ,聚合初期加入大量引发剂可同时提高单体转化率和乳胶粒的单分散性 ;随着引发剂和AA用量的增加以及聚合温度的升高 ,胶粒粒径逐渐减小 ,转化率逐渐升高 ;随着NH4 HCO3用量的增加 ,粒径逐渐增大 ,当NH4 HCO3用量达到 0 5g以后 ,转化率逐渐降低 ;搅拌速率为 30 0r min左右时 ,单体转化率最高 ,所得乳胶粒粒径最均一 .

CONTROL OF PARTICLE SIZE AND ITS DISTRIBUTION IN SOAPFREE EMULSION COPOLYMERIZATION OF MMA-EA-AA

The control of particle size and its distribution has become more and more important both in theory and in practice in emulsion polymerization field.In this study,emulsion polymerization of methyl methacrylate (MMA),ethyl acrylate (EA) and acrylic acid (AA) was carried out in the absence of emulsifier,and the influences of ingredients and conditions on polymerization,latex particle size and its distribution were investigated,and latex particles with narrow size distribution as well as with carboxyl groups on their surface were synthesized.The results showed that the high monomer conversion and narrow latex particle size distribution were obtained when large amount of initiator (APS) was introduced into the polymerization system at the beginning in three-step addition process.With the increase of APS and AA,the particle size decreased and the monomer conversion increased,and a similar result was also observed with the temperature increase.It was found that NH 4HCO 3 is a key material for the control of particle diameter (D p). D p increased with the increase of amount of NH 4HCO 3,and the D p of monodispersed P(MMA-EA-AA) latex particles can be well controlled in the range from 300 to 600?nm by adjusting the amount of NH 4HCO 3 used.Moreover,latexes with high monomer conversion and narrow particle size distribution can be obtained when a moderate stirring rate of 300 r/min was selected.