材料期刊网

以苯乙烯(St)、甲基丙烯酸甲酯(MMA)为主单体,丙烯酸(AA)为功能单体进行了无皂乳液批量共聚合。用电导滴定法测定了羧基在胶乳中的分布,讨论了功能单体AA浓度、引发剂APS含量、体系pH值、聚合温度及St／MMA比例对胶乳中-COOH分布的影响。结果表明,随AA浓度增大,表面羧基百分比减小、而包埋百分比增大、胶粒表面羧基密度增大。引发剂APS浓度、MMA比例及聚合温度的提高,不利于羧基分布在乳胶粒表面,胶粒表面羧基密度减小。体系pH值增大,有利于羧基位于胶粒表面,表面羧基密度有所增加。

The emulsifier-free emulsion copolymerization and styrene (St) and methyl methacrylate (MMA) in the presence of functional monomer acrylic acid (AA) was carried out in batch process. The distribution of -COOH in the latex was determined by coductometric titration and the densityof surface -COOH was computed. Effects of concentration of AA and APS, pH value, polymerization temperature (T) and molar ratio of MMA on the distribution of -COOH and density of surface -COOH were investigated. The results show that percent of buried -COOH(Bp) and density of surface -COOH(Dc) increases, percent of surface -COOH(Sp) decreases with increasing［AA］; increasing the pH value will benefit -COOH being located on the surface of latex particle and Dc increases; increasing ［APS］, T and molar ratio of MMA will not benefit -COOH being distributed on the surface of latex and Dc decreases.