Prediction of the Phase Structure Evolution during Processing of Polymer Blends. Results and Problems

摘要

The paper summarizes state of art in the description of the droplet breakup, coalescence, and competition between them in flowing immiscible polymer blends. It has been shown that, in contrast to the conditions for the start of droplet breakup, knowledge of the dependence of the droplet breakup frequency on system parameters is quite limited. It has been demonstrated that the switch between expressions for thematrix drainage between spherical and highly deformed droplets leads to a reasonable description of the flow induced coalescence. This method makes it possible to include the effect of the matrix elasticity into the calculation of the probability of coalescence. The analysis of the competition between the droplet breakup and coalescence leads to the conclusion that knowledge of the mechanism and frequency of the droplet breakup is essential for at least qualitative prediction of the droplet size dependence on system parameters. The article addresses main features of flowing polymer blends, not adequately reflected in available theories.