Theoretical and numerical studies on viscoelastic effect in phase separation of polymeric systems

Viscoelastic effects on phase separations in polymeric systems are investigated by a numerical method using a two fluid model. In the viscoelastic phase separation, the Coupling of solvent diffusion and stress stored in polymeric materials strongly influences the dynamics, morphology of phase separated pattern. In our model we take into account the coupling and explain unusual phase separation phenomena observed experimentally in polymer solution systems. In our simulations, we reproduced the network pattern of polymer rich phase which is a minority phase and found that the coarsening of the network pattern is very slow. In order to clarify the origin of slowing down of coarsening dynamics of network pattern of polymer rich phase,we investigated the dynamics of an initially elongated droplet. We found that the flow field induced by the surface tension of droplet is suppressed by the stress produced by the induced flow field.