Dynamic behavior of model polymer fluids

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5720689

Rudisill, J W

The goal of this dissertation research is to study kinetic theory models for polymers undergoing planar Couette shear flow using molecular simulation techniques. Non-equilibrium molecular dynamics (NEMD) simulations have been used to study polymer melts. Infinitely dilute solutions have been simulated using non-equilibrium Brownian dynamics (NEBD). In the NEMD study, rigid and elastic dumbbell fluids are simulated to determine the contribution of internal degrees of freedom to strain rate dependent shear viscosity. The model adopted for elastic molecules is a modification of the finitely extensible nonlinear elastic (FENE) dumbbell commonly used in kinetic theories of polymer solutions. The model polymer melts considered are fluids composed of rigid dumbbells and of FENE dumbbells. The rheological properties of the rigid and FENE dumbbells are found to be qualitatively and qantitatively similar. The rheological properties of the two dumbbell fluids are compared to those of a corresponding fluid of spheres which is shown to be the most non-Newtonian of the three fluids considered. The results of NEBD simulations of dilute model polymer solutions in a shear flow are reported. Hydrodynamic interactions (HI) are modeled by the Rotne-Prager-Yamakawa tensor with excluded volume (EV). The rheological properties of Hookean and FENE bead and spring models are compared. Finite extensibility is found to be a more important factor in predicting shear thinning behavior than EV or HI.

• Research Organization: Virginia Univ., Charlottesville, VA (United States)
• OSTI ID: 5720689
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
360606* -- Other Materials-- Physical Properties-- (1992-)
COUETTE FLOW
DEGREES OF FREEDOM
DYNAMICS
FLUID FLOW
FLUIDS
MECHANICS
MELTING
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POLYMERS
SHEAR
THERMODYNAMIC PROPERTIES
VISCOSITY
VISCOUS FLOW