Brownian dynamics simulation study on the anisotropic FENE dumbbell model for concentrated polymer solution and the melt

We study the rheological properties of concentrated polymer solution and th e melt under simple shear and elongational flow using Brownian dynamics sim ulation. In order to describe the anisotropic molecular motion, we modified the Giesekus' mobility tensor by incorporating the finitely extensible non -linear elastic (FENE) spring force into dumbbell model. To elucidate the n ature of this model, our simulation results are compared with the data of F ENE-P ("P" stands for the Perterin) dumbbell model and experiments. While i n steady state both original FENE and FENE-P models exhibit a similar visco sity response, the growth of viscosity becomes dissimilar as the anisotropy decreases and the flow rate increases. The steady state viscosity obtained from the simulation well describes the experiments including the shear-thi nning behavior in shear flow and viscosity-thinning behavior in elongationa l flow. But the growth of viscosity of original FENE dumbbell model cannot describe the experimental results in both flow fields.