嵌段共聚物对不相容聚合物共混体系的增容研究

发布时间：2018-04-30 19:51

本文选题：聚合物共混 + 相容性　；参考：《宁波大学》2017年硕士论文

【摘要】：高分子共混改性已经成为获取新型材料更加便捷经济的方式,然而共混组分间的不相容严重制约着共混材料的性能和应用。使用有效的增容剂来增加体系组分间的相容性对于新材料的制备和应用具有显著的经济价值。嵌段共聚物由于特殊的分子结构常被用于增容不相容的共混聚合物,但是嵌段共聚物在临界胶束浓度之上时,容易在共混物中形成胶束,从而降低了嵌段共聚物的利用率。因此,研究嵌段共聚物的增容机理对提高嵌段共聚物的增容应用具有重要的理论和实际价值。本文采用PS-b-PMMA(SM)为增容剂,通过熔融共混制备了SM/PMMA/PCHMA和SM/PS/PMMA的共混物。系统研究了加工条件、SM的分子结构和含量对共混物形态的影响,探究了SM相容剂形成的胶束结构以及其在共混物界面间的迁移行为。采用透射电子显微镜和旋转流变仪对共混物的微观形态和流变行为进行了表征。主要结论如下:1.研究了剪切强度、共混时间和加料顺序对SM/PMMA/PCHMA共混物中PMMA粒子的粒径和粒径分布的影响。研究发现,当剪切速率为100rpm时,PMMA粒子的尺寸和分布最小。SM嵌段共聚物延长了共混物的形态达到平衡的时间。嵌段共聚物的增容效率与其在共混物中的溶解度有关,将SM优先加入到溶解度高的PCHMA相中,增容剂的利用率最高。2.比较了SM在PCHMA和PMMA中形成的胶束结构,考察了不同分子量的SM在PCHMA/PMMA界面上的迁移行为。采用旋转流变仪表征了不同分子量的SM在PCHMA/PMMA界面上的粘结程度。结果表明,SM在PCHMA和PMMA中都形成“核-壳”结构的胶束。SM在PCHMA中形成以PMMA为核的胶束,在PMMA相中形成以PS为核的胶束。SM只有在PCHMA/PMMA界面上形成“湿刷”时,在PCHMA中形成的胶束才能迁移到PMMA中。SM分子量在50kg/mol时,可以获得最小的PMMA粒子尺寸和分布。3.采用分子构造不同的SM增容PMMA/PCHMA和PS/PMMA共混物,研究了SM的含量和分子结构对共混物形态的影响。结果表明,随着SM含量的增加,共混体系中PMMA分散相尺寸不断减小。共聚物中SM链段越短,达到共混体系界面的时间越短,但不能有效稳定共混物在热退火过程中的相形态。增容剂SM的链段长于共混各组分的链长时,SM不仅能够有效的降低分散相粒子的尺寸,而且能有效稳定共混体系的结构。SM中较长的链段位于稀相时,会抑制分散相粒子稀相纤维的破裂,从而提高分散相的连续度。
[Abstract]:Polymer blending modification has become a more convenient and economical way to obtain new materials. However, the properties and applications of the blends are seriously restricted by the incompatibility between the components of the blends. The use of effective compatibilizers to increase the compatibility between the components of the system has significant economic value for the preparation and application of new materials. Block copolymers are often used to compatibilize incompatible blends because of their special molecular structure, but when the block copolymers are above the critical micelle concentration, micelles are easily formed in the blends, thus reducing the utilization ratio of block copolymers. Therefore, the study of the compatibilization mechanism of block copolymers has important theoretical and practical value in improving the compatibilization and application of block copolymers. The blends of SM/PMMA/PCHMA and SM/PS/PMMA were prepared by melt blending using PS-b-PMMA-SMas as compatibilizer. The effects of the molecular structure and content of SM on the morphology of the blend were studied systematically. The micelle structure of SM compatibilizer and its migration behavior at the interface of the blend were investigated. The microstructure and rheological behavior of the blends were characterized by transmission electron microscopy and rotary rheometer. The main conclusions are as follows: 1. The effects of shear strength, blending time and feeding order on the particle size and distribution of PMMA particles in SM/PMMA/PCHMA blends were studied. It was found that when the shear rate was 100rpm, the size and distribution of PMMA particles were the smallest. SM block copolymers prolonged the equilibrium time for the morphology of the blends. The compatibilization efficiency of block copolymers is related to their solubility in the blends. SM is added to the PCHMA phase with high solubility, and the compatibilizer has the highest utilization ratio. The micelle structure of SM formed in PCHMA and PMMA was compared and the migration behavior of SM with different molecular weight at PCHMA/PMMA interface was investigated. The adhesion of SM with different molecular weight at PCHMA/PMMA interface was measured by rotating rheometer. The results showed that the "core-shell" micelles formed in both PCHMA and PMMA. SM formed micelles with PMMA in PCHMA and micelles with PS as core in PMMA phase. SM only formed "wet brushes" at the interface of PCHMA/PMMA. The micelles formed in PCHMA can be transferred to PMMA. SM molecular weight is in 50kg/mol, and the smallest PMMA particle size and distribution. 3 can be obtained. The effects of SM content and molecular structure on the morphology of PMMA/PCHMA and PS/PMMA blends were studied. The results show that the size of PMMA dispersed phase decreases with the increase of SM content. The shorter the SM segment in the copolymers, the shorter the time to reach the interface of the blends, but the phase morphology of the blends cannot be effectively stabilized during thermal annealing. When the chain length of the compatibilizer SM is longer than that of each component of the blend, SM can not only effectively reduce the size of dispersed particles, but also effectively stabilize the structure of the blend. The longer segment of SM is located in the dilute phase. It can inhibit the breakdown of the dispersed particle rare-phase fiber and increase the continuity of the dispersed phase.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O631

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