溴化反应条件对溴化丁基橡胶微观结构的影响

The Effects of Bromination Condition on the Microstructure of Brominated Butyl Rubber

通过溶液法制备溴化丁基橡胶,并用核磁共振对溴化丁基橡胶的微观结构进行了分析,其中存在3种主要微观结构,即未溴化的丁基橡胶结构(结构Ⅰ),溴代仲位烯丙基结构(结构Ⅱ)及溴代伯位烯丙基结构(结构Ⅲ)。考察了反应时间、中和后停留时间及中和后pH值对溴化丁基橡胶的微观结构的影响。结果表明,丁基橡胶的溴化过程只在最初的1.5min内,随着反应时间的延长及在碱性条件下反应,发生了分子结构的重排,即由溴代仲位烯丙基结构向更稳定溴代伯位烯丙基结构转移。

Brominated butyl rubber was prepared by solution method,and its microstructures were characterized by 1H-NMR. It has three main microstructures,that is the unbrominated isoprene structure （structureⅠ）,the exomethylene allylic bromide structure （structure Ⅱ） and the bromomethyl olefinic structure （structure Ⅲ）. The effects of contact time,residence time and pH after neutralization on microstructures were investigated. The results show that the brominated reaction is complete in 1.5 initial contact minutes,and prolonging contact time or under alkaline condition can accelerate isomerization of brominated butyl rubber from structure to structure Ⅲ.