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Nucleation mechanisms in the emulsion polymerization of styrene at different surfactant concentrations

XU Bingwen1,WANG Hong2,HE Yanping1,XIAO Xiaoqin1,SUN Yanlin1   

  1. 1Faculty of Chemical Engineering,Kunming University of Science and Technology,Kunming 650500,Yunnan,China;2Faculty of Science,Kunming University of Science and Technology,Kunming 650093,Yunnan,China
  • Online:2014-11-01 Published:2014-11-05

乳化剂浓度对苯乙烯乳液聚合成核机理的影响

许冰文1,王红2,何艳萍1,肖小琴1,孙彦琳1   

  1. 1昆明理工大学化学工程学院,云南 昆明 650500;2昆明理工大学理学院,云南 昆明 650500

Abstract: Formulation of latex with styrene (St),potassium persulfate (KPS) and sodium dodecyl sulfate (SDS) was investigated as a function of SDS surfactant concentration [S] to explore its nucleation mechanism. The results showed that micellar nucleation dominated the nucleation process when the concentration of SDS was ≥ 8 mmol/L; while,precipitation nucleation dominated the process at 2mmol/L. From 2mmol/L to 8mmol/L,both micellar nucleation and precipitation worked; and the contribution of micellar nucleation increased with the increase of the concentration of SDS. Additionally,the particle number of latex was calculated:Np∝[S]0.9 when [S] was ≥8mmol/L; Np∝[S]0.8 when 8mmol/L≥[S]≥2mmol/L.

Key words: emulsions, nucleation mechanism, surfactant concentration, particle size distribution

摘要: 以苯乙烯(St)为单体、十二烷基硫酸钠(SDS)为乳化剂、过硫酸钾(KPS)为引发剂,重点研究了该乳液聚合体系中乳化剂浓度([S])对胶束成核和沉淀成核的影响规律。结果表明,当SDS浓度高于CMC时([S]≥ 8mmol/L),体系的成核以胶束成核为主;当[S]=2mmol/L时,体系的成核以沉淀成核为主;当2mmol/L<[S]< 8mmol/L时,体系同时以沉淀成核和胶束成核两种方式成核,且胶束成核所占的比例随着SDS浓度的增加而增大。研究了聚合反应过程中SDS浓度对单位体积水中乳胶粒个数(Np)的影响规律:当[S]≥8mmol/L时,Np∝[S]0.9;当[S]<8mmol/L时,Np∝[S]0.8。

关键词: 乳液, 成核机理, 乳化剂浓度, 粒度分布