凝胶化反应全过程的激光光散射跟踪研究

在苯乙烯（Ｓｔ） 二乙烯苯（ＤＶＢ）自由基共聚的凝胶化反应过程中定时取样，得到凝胶化点前后及至终点的一系列样品，然后用激光光散射技术，包括研究散射光强及其角度依赖性的静态光散射（ＳＬＳ）和研究散射光频移的动态光散射（ＤＬＳ），表征了这系列样品的重均分子量Ｍｗ、均方旋转半径Ｒｇ、第二维利系数Ａ２及流体力学半径Ｒｈ等静、动态参量及这些参量的变化规律，定量地描述了凝胶化反应全过程

A STUDY OF SPAN PROCESS OF GELATION BY LASER LIGHT SCATTERING

During the copolymerization of styrene with divinylbenzene,a series of samples were taken at different gelation time from the beginning to the end of this reaction.For sol samples before and after gelation point time Tg(=18 15h),the weight average molecular weight (M w), the mean square radius of gyration (R g) of the polymer chain in solution,the second virial coefficient (A 2),hydrodynamic radius (R h),parameter δ(=R g/R h) and the size distribution for these samples were determined by static light scattering and dynamic light scattering.Before T g,both M w and R g increase rapidly,then become divergence near T g and reach the maximum at Tg. R h almost follows the same way except not so rapidly.After T g,all go down.A 2 decrease gradually following the gelation.δ are 278,380 and 187 at 15h,18 25h and 29h,respectively,which agree with the rules of linear and branching polystyrene.The size distribution of these sol samples always were rather wide and before T g and after Tg,their diameters tend to increase and decrease,respectively.Based on these data,the evolution rules of these parameters were withdrawn and the quantitative characterization of span process of gelation was carried out successfully.