Development of Highly Precise Controlling Methods for Polymer Microspher by Taking Advantage of Nonlinear Dynamics

本研究试图利用连续乳液聚合过程中的非线性动力学来控制乳胶粒子的粒径分布。在CSTR中，当乳化剂的临界胶束浓度低于临界胶束浓度时，在临界反应温度或平均停留时间下，与时间无关的稳态操作所获得的单体转化率从0急剧上升到60%以上。在非稳态操作中，平均停留时间或反应温度在两个值之间交替切换，一个在通常的稳态操作中提供零单体转化率，另一个提供高单体转化率。周期切换操作在时间上引起了单体转化率的振荡。随着切换操作的进行，颗粒大小分布发生同步变化。这项研究表明，通过调整…来控制颗粒尺寸分布是可能的更多的是平均停留时间或反应温度的时间变化的频率和/或幅度。研究发现，即使在保持恒定的单体转化率的情况下，颗粒的粒度分布也会以很大的时间周期振荡。研究表明，这种振荡是通过聚合反应和胶乳粒子聚集之间的竞争相互作用而发生的。为了改变胶乳粒子的胶体稳定性，在某些情况下添加了非离子表面活性剂。研究发现，使用非离子表面活性剂和阴离子表面活性剂的混合物可以非常有效地抑制振荡。为了利用粒径的波动，在串联的两个连续搅拌釜式反应器系统中进行了乙酸乙烯乳液聚合。通过改变叶轮转速和平均停留时间可以控制其振荡行为。串联使用两个CSTR的研究表明，生产各种多分散乳胶粒子的可能性。较少

This research attempted to take advantage of the nonlinear dynamics in continuous emulsion polymerization processes in order to control latex particle size distribution. When the emulsion polymerization of vinyl acetate was conducted in a CSTR under conditions below the critical micelle concentration of the emulsifier, the monomer conversion attained in a time-independent steady-state operation showed a drastic rise from 0 to over 60% at a critical reaction temperature or mean residence time. The mean residence time or the reaction temperature was switched alternately between two values in the non-steady-state operation, one giving zero monomer conversion and the other a high monomer conversion in the usual steady-state operation. The periodic-switching operation induced oscillations in monomer conversion in time. The particle size distribution varied synchronously with the switching operation. This research showed the possibility of controlling the particle size distribution by adjust … More ing the frequency and/or the amplitude of the temporal variation of the mean residence time or reaction temperature. This research found that even while the constant monomer conversion was maintained at the steady state, the particle size distribution oscillated with a very large time period. This research revealed that the oscillations occur by a competitive interaction between polymerization reaction and aggregation of latex particles. In order to vary the colloidal stability of latex particles, a nonionic surfactant was added in some cases. It was found that using a mixture of a nonionic surfactant and an anionic surfactant was very effective for suppressing the oscillations. In order to take advantage of the oscillations of particle size, emulsion polymerization of vinyl acetate was performed in a system of two continuous stirred tank reactors in series. The oscillatory behavior could be controlled by varying the rotational speed of the impeller and the mean residence time. The research using two CSTR in series indicated the possibility of producing various poly-dispersed latex particles. Less