补加乳化剂提高丁二烯/苯乙烯的聚合速率

以丁二烯/苯乙烯乳液聚合反应10h、转化率达到70%为研究目标,在分析了标准配方条件下提高转化率对反应时间影响的基础上,考察了补加乳化剂对反应后期聚合速率及胶乳黏度、粒径和机械稳定性的影响,与采用增加初始乳化剂法进行了对比,并探讨了补加乳化剂提高反应后期聚合速率的作用机理。结果表明,增加初始乳化剂用量可以显著提高聚合速率,但胶乳黏度明显增大,且机械稳定性降低;补加乳化剂有利于提高反应后期的聚合速率和胶乳的机械稳定性;乳化剂补加量越大,反应后期的聚合速率越快;当乳化剂补加量相同时,在反应时间为2～4h,补加时机越早,反应后期聚合速率越快;补加乳化剂的最佳工艺条件为:乳化剂初始量100%,补加量10%,补加时机为反应2h。

Increasing polymerization rate of butadiene/styrene via addition emulsifier

To reach 70% of conversion within 10 h in butadiene/styrene emulsion polymerization system,the effects of addition emulsifier on polymerization rate in the later stage of polymerization,viscosity,particle diameter and mechanical stability of styrene-butadiene latex were investigated systematically and compared with that of increasing the amount of initial emulsifier,based upon the effect of improving monomer conversion on polymerization time in general recipe condition.The mechanism of addition emulsifier for increasing polymerization rate in the later stage of polymerization was approached in detail.The results showed that polymerization rate increased considerably by increasing the amount of initial emulsifier,but latex viscosity increased notably and latex mechanical stability declined obviously.Addition emulsifier was of benefit to increasing polymerization rate in the later stage of emulsion polymerization and to improving latex mechanical stability.The larger the amount of addition emulsifier at the same addition time,the faster the polymerization rate in the later stage.At the same amount of addition emulsifier,the earlier the addition time during reaction time 2~4 h,the faster the polymerization rate in the later stage.The optimum technological condition was as follows:the amount of initial emulsifier was 100%,the addition amount of emulsifier was 10%,and the addition time was at polymerization time 2 h.