بررسي مدلهاي ريولوژيكي صورتبندي براي مذابها و محلولهاي غليظ پليمري

Investigation of Conformational Rheological Models for Polymer Melts and Concentrated Solutions

In this study, some internal microstructural models with different mobility tensors are investigated for polymer melts and concentrated solutions in shear flow. The time evolution equations for conformation and stress tensors in the reviewed models have root in the generalized Poisson Bracket formalism. Two different families of conformational models have been selected for this study. The first family is with the finitely modified extensible non-linear elastic (FENE-P) energy and the other family is with the Hookean Helmholtz free energy function. Several expressions for the mobility tensor with the mentioned energy functions are used to obtain those models. The sensitivity of both models towards the choice of the mobility tensor on the prediction of material functions in transient and steady flows is discussed. Also, the effect of shear rate on the material functions in start-up and relaxation shear flows for both models are studied. The predictions of models are compared to experimental data taken from the literature for some polymer melts. These results show that the families of volume preserving rheological models are able to predict the shear flow material functions in steady and transient regimes in an extended range of deformation rate, where the family of FENE-P models can only predict the behavior of some specified polymer melts.