A Constitutive Model Describing Molecular Configuration Evolution and Transient Rheological Behavior of Entangled Polymer Solutions

Abstract

The entanglement network is an important structural feature in polymer 10 concentrated solutions and melts, which has a great influence on the transient 11 rheological behavior and molecular configuration evolution. However, the existing 12 constitutive models have limitations in describing the influence of dynamic 13 entanglement behavior on molecular chain motion, resulting in inaccurate descriptions 14 of the transient rheological behavior. Thus, a molecular configuration evolution model 15 for polymer solutions considering the dynamic entanglement effect is proposed by 16 introducing an intermolecular force that changes with the orientation of the molecular 17 chain in this work. The intermolecular force is introduced by considering the friction 18 coefficient as anisotropic, and the orientation effect is considered by introducing an 19 excluded volume dependent anisotropic diffusion. The proposed model can better 20 describe the stress relaxation, stress growth, and dielectric anisotropy of polymer 21 solutions compared with the anisotropy FENE model and FENE model, which means 22 the proposed model can better describe the transient rheological behavior and 23 configuration evolution of polymer solutions. In addition, the influence of different 24 model parameters on the transient and steady shear response of polymer solution is 25 investigated, and the results show that the influence of volume loss on the friction 26 anisotropy factor kσ increases as the solution concentration increases.