无皂乳液制备PMMA动力学及其模型

以甲基丙烯酸甲酯(MMA)为单体、过硫酸钾(KPS)为引发剂进行无皂乳液聚合反应,考察了单体MMA浓度、引发剂KPS用量及聚合温度对其动力学行为的影响。建立了转化率-时间关系曲线的模型函数———Gamm a积分函数,用它拟合了转化率-时间关系曲线,获得了聚合过程的重要特征参数,如平均成核速率,聚合最大速率和平稳期平均聚合速率及成核结束和聚合进入完成期对应的转化率。同时对聚合速率与以上各聚合参数的关系数据进行了非线性拟合,得到了它们之间的关系式。拟合相关系数非常接近于1,平均拟合误差很小,成核结束时转化率在15%以内,聚合速率随以上参数增大而增大,反应温度在聚合过程中起决定作用。

Kinetics and model of free emulsion polymerization of PMMA

The emulsifier-free emulsion polymerization of methyl methacrylate was carried out in batch mode.Effects of concentration of monomer MMA,initiator concentration of KPS and polymerization temperature on the kinetics of the polymerization were investigated.Model function of conversion vs.reaction time-Integrated Gamma Function was built up and was employed to fit the data of conversion versus reaction time.The maximum polymerization rate,average polymerization rate in the steady stage,average nucleation rate and the corresponding conversions at moment of nucleation stage ceasing and at the steady stage were estimated by calculating extremums and inflexions of it's fitted Gamma Function.After the polymerization rate versus each single polymerization parameter was analyzed with non-linear fitting,the related equation was obtained.The results show that the fitting error is small and polymerization rate increase with increasing , and polymerization temperature.Among these reaction parameters,temperature plays a predominant role in the polymerization.The conversion is within 15% when the nucleation stage ends.