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在甲基丙烯酸甲酯(MMA)和丙烯酸正丁酯(BA)的无皂乳液共聚体系中,加入适量反应性乳化剂w-十一烯酸钠(SUA),在用量远低于其CMC时,分别讨论了SUA浓度、引发剂(K_2S_2O_8)浓度以及离子强度对反应动力学的影响,用SA-CP3型粒度分布仪、透射电镜(TEM)等考察了乳液粒子大小(D_w)、浓度(N_p)、形态及其增长过程;用凝胶渗透色谱仪、红外光增、离子交换-电导滴定等手段探讨了反应机理。结果表明:在该反应体系中,“均相沉淀”与“胶束”成核两种机理同时存在,两种成核方式几率的相对大小由SUA浓度、离子强度等所决定。
In the soap-free emulsion copolymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA), the appropriate amount of reactive emulsifier sodium w-undecylenate (SUA) was added. The effect of SUA concentration, initiator (K 2 S 2 O 8) concentration and ionic strength on the reaction kinetics was discussed. The particle size (D_w) and concentration (N_p) of the emulsions were investigated by SA-CP3 particle size distribution analyzer and transmission electron microscope ), Morphology and growth process. The reaction mechanism was discussed by means of gel permeation chromatography, infrared spectroscopy, ion exchange - conductometric titration and so on. The results show that there are two mechanisms of “homogeneous precipitation” and “micellar” nucleation in the reaction system. The relative sizes of the two nucleation modes are determined by SUA concentration and ionic strength.