Brownian dynamics of dilute semirigid chains
Abstract
The purpose of this thesis is to study the rheological and geometric properties of a linear Kirkwood-Riseman freely rotating bead-rod chain using Brownian dynamics. This thesis models the linear polymer as of chains of twenty, fifty and eighty beads at equilibrium and at different steady shear flows. The geometric properties (end-to-end distance, square radius of gyration contour length and inertia tensor) suggest that the chains orient with the direction of the flow and do so more strongly with increasing shear rate. The chains present a maximum extension at an intermediate shear rate around $\lambda\dot\gamma$ = 10, and at higher shear rates they are more contracted. The rheological results--especially the viscosity--show three different regimes: one power law regions between two Newtonian regions. The different motion mechanisms in these regions, not clear till the present, are explained. In particular the second Newtonian region has recently been observed experimentally. Some preliminary structure factor results are presented for future light scattering experiments.
Degree
Ph.D.
Advisors
Wiest, Purdue University.
Subject Area
Chemical engineering
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.