Three-dimensional numerical simulation of viscoelastic phase separation under shear: the roles of bulk and shear relaxation moduli

Abstract

The morphological, dynamic and rheological characteristics in the viscoelastic phase separation (VPS) of sheared polymer solutions are investigated by three-dimensional (3D) numerical simulations of viscoelastic model. The simulations are accelerated by graphic process unit (GPU) to break through the limitation of computation power. Firstly, the morphological and dynamic characteristics of VPS under shear are presented by comparing with those in classic phase separation (CPS). The results show that the phase inversion and phase shrink take place in VPS under shear. Then, the roles of bulk and shear relaxation moduli in VPS are investigated in details. The bulk relaxation modulus slows down the phase separation process under shear, but not affects the dynamic path of VPS. The dynamic path can be divided into three stages: freezing stage, growth stage and stable stage. The second overshoot phenomenon in the shear stress is observed, and explained by the breakdown and reform of string structures. The shear modulus affects morphology evolution in the late stage of VPS under shear.