Rheologically Determined Different Phase Separation Mechanisms in Polymer Blends

Phase separation is one of the most fundamental physical phenomena that creates patterns in nature and in materials. Understanding the phase separation mechanisms and controlling the morphological evolution are very important to design various advanced materials with novel mechanical, optical, electrical and transport properties. In this study we study the time evolution of linear and nonlinear rheological behaviour of different phase separation mechanisms (spinodal decomposition, nucleation and growth, and viscoelastic phase separation), in other words different morphologies (co-continuous, droplet-matrix, network) in PS/PVME blend. To study linear rheology different analyses have been used: dynamic frequency sweep behavior, Cole– Cole plot, van Gurp–Palmen plot, isothermal time sweep of storage modulus. In the nonlinear regime start-up shear flow experiment has been employed. We observed that rheology is a sensitive tool to study different phase separation mechanisms, in other words different morphologies

Keywords:

Rheology , Phase separation , Dynamic asymmetry , co-continuous , droplet-matrix , network