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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p H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 p H值增大 ,有利于羧基位于胶粒表面 ,表面羧基密度有所增加
A soap-free emulsion batch copolymerization of styrene (St) and methyl methacrylate (MMA) with acrylic acid (AA) as functional monomer was carried out. The distribution of carboxyl groups in latex was determined by conductometric titration. The effects of AA concentration, initiator APS content, system pH value, polymerization temperature and St / MMA ratio on the distribution of - COOH in latex were discussed. The results showed that with the increase of AA concentration, the percentage of carboxyl groups on the surface decreased and the percentage of embedding increased, and the carboxyl group density on the surface of micelles increased. The concentration of initiator APS, the proportion of MMA and the increase of polymerization temperature are not conducive to the distribution of carboxyl groups on the surface of the latex particles, and the carboxyl group density on the surface of the particles decreases. The increase of the value of p H of the system is conducive to the carboxyl group located on the surface of the colloid particles and the increase of the surface carboxyl group density