氧化-还原低温引发苯乙烯/丙烯酸丁酯细乳液共聚合动力学与成核机理的研究

详细讨论了 (NH4 ) 2 S2 O8/NaHSO3 ]氧化 还原引发体系引发苯乙烯 (St)丙烯酸丁酯 (BuA)体系的细乳液共聚合的动力学特征及其与成核机理的关系 .细乳液的聚合速率比相同条件下的常规乳液聚合速率低 ,引发期长 .随聚合温度、引发剂浓度、乳化剂浓度的增加 ,聚合速率增大 .共乳化剂正十六烷 (HDE)的浓度在一定范围内增大 ,反应的速率增大 ,然后再增加HDE ,反应速率下降 .建立动力学曲线数学模型 ,并深入讨论了细乳液的聚合动力学特征 ,与常规乳液所得结果相比较 ,探讨了细乳液的单体液滴成核机理 .

STUDY ON KINETICS AND NUCLEATION MECHANISM OF St-BA MINIEMULSION POLYMERIZATION WITH REDOX INITIATORS

Miniemulsion of styrene and butyl acrylate with sodium dodecyl sulfate (SDS) as surfactant and hexadecane (HDE) as cosurfactant was prepared under ultrasonification,then the miniemulsion copolymerization was carried out with a redox initiator ((NH\-4)\-2S\-2O\-8/NaHSO\-3) at lower temperature.The effects of temperature and concentrations of surfactant,cosurfactant,and initiator on the polymerization rate and conversion were determined.Under the same conditions,the polymerization rate of miniemulsion was lower than that of conventional emulsion and the initiation period was much longer.Polymerization rate increased with the increase of recreation temperature and the concentration of initiator,and surfactant.In a certain range,the polymerization rate increased with increasing HDE concentration.However,beyond that range,it decreased with increasing HDE concentration.By using computer treatment of the experimental data,a mathematical model was established for miniemulsion kinetics,then studied the kinetics characters in detail.By comparing with the results of conventional emulsion,a “monomer droplet nucleation” mechanism of miniemulsion was proposed.