乙烯基单体乳液接枝改性氯丁胶乳的制备及接枝机理研究

采用乳液聚合法，使用氧化还原引发剂，将乙烯基单体（甲基丙烯酸甲酯MMA、苯乙烯 St）接枝到氯丁胶乳上。研究了乳化体系、引发体系、单体/聚合物配比（M/P）及单体组成和反应温度对单体转化率、接枝效率等的影响，分析了乳液接枝机理。结果表明， MMA和St接枝改性氯丁胶乳的最佳工艺条件为：聚合温度为50℃，反应时间5.5h，引发剂叔丁基过氧化氢一四乙烯五胺（t-BHP/TEPA）用量占氯丁胶乳干重的0.5 %，M：P =3：5，WMMA：WSt=3:2，单体以滴加方式加入，乳化剂十二烷基苯磺酸钠 （SDBS）用量占单体总重1.5%，此时单体转化率可达99.6%，接枝效率为54.9%。红外光谱和凝胶含量分析证明MMA和St接枝到氯丁胶乳主链上。在最佳条件下合成的接枝共聚物乳液配制成的胶粘剂对PVC人造革、SBS橡胶、海绵等具有良好的粘接性能。接枝反应活性点在氯丁胶乳胶粒的表面，接枝过程是一个表面控制过程。

Preparation and Grafting Mechanism of Chloroprene Latex Modified with Vinyl Monomers by Emulsion Polymerization

Grafting of methyl methacrylate (MMA) and styrene (St) onto chloropren (CR) latex was carried out by emulsion polymerization using tert-butyl hydroperoxide/tetraethylenepentamine (t-BHP/TEPA) as redox initiator. The effects of the emulsifier system, the initiator type and concentration, the monomer to polymer ratio and the reaction temperature on the monomer conversion and the grafting efficiency were investigated, and the emulsion grafting mechanism was also analysed. The results showed that the monomer conversion and the grafting efficiency could be reached 99.6%, 54.9%, respectively, under the condition of mass ratio of monomer to polymer was 3:5, methyl methacrylate to styrene was 3:2, the amount of initiator was 0.5 wt% (based on the weight of dry CR), the amount of emulsifier sodium dodecylbenzenesulfonate was 1.5 wt% (based on the weight of monomers), and the reaction temperature was 50℃. FTIR and gel content analysis confirmed that MMA and St were grafted onto the chloroprene latex particles. The adhesive obtained from graft copolymer had good adhesion to PVC, SBS rubber and sponge. There were reaction locis on the surface of the latex particles, and the surface-controlled process model was proposed to describe the grafting mechanism.