丁苯乳液共聚合动力学的研究

Kinetics of Copolymerization of Butadiene and Styrene in Emulsion

本文详细考察了高转化率下各种因素对丁苯乳液共聚合速率的影响。以过硫酸钾为引发剂,岐化松香皂和硬脂酸钾的混合物为乳化剂,正十二硫醇为链转移剂,在5升不锈钢高压釜中进行了丁苯乳液共聚合实验。随着乳化剂和引发剂浓度的增大、乳化剂中硬脂酸钾相对量的增加以及温度的升高,聚合速率均加快;加入少量电解质可以提高聚合速率;加入少量硫醇与完全不加硫醇相比,聚合速率有很大提高。另外,还发现氧对聚合有明显的阻聚作用、水油比对单体转化速率影响不大。同时理论推导了乳胶粒数随时间的变化关系,并在自由基聚合机理,乳胶粒中单体浓度连续下降等假设的基础上推导了高转化率下乳液聚合的数学模型,对于丁二烯、苯乙烯共聚体系,模型计算值与实验值能较好的吻合。

The rate of emulsion copolymerization of butadiene and styrene was studied in this work. It shows that the rate of copolymerization increases with the increase of the temperature, the concentration of emulsifier, the initiator, and the amount of potassium stearate in emulsifier. With small amount of electrolyte, such as potassium chloride, the rate of copolymerization can be aoceralated, and small amount of n-dodecanethiol can acceralate the copolymerization reaction even greater. But oxygen in air is a kind of retarder for copolymerization reaction.A theoretical model was derived to correlate the relationship between the number of latex particles and reaction time for the emulsion copolymerization. Based on the assumptions that the concentration of monomers in latex particles decreases continuously and the formation of latex particles happens when copolymerization reaction progresses, a mathematical model was developed to predict the convarsion rate of monomers. The model prediction is in good agreement with experimental results.