Paper Number
PO95 

Session
Poster Session

Title
Molecular scale simulation of shear, parabolic, and extensional flow: Implementation and findings

Presentation Date and Time
October 8, 2014 (Wednesday) 6:05

Track / Room
Poster Session / Poster

Authors (Click on name to view author profile)

1. Rorrer, Nichoals A. (Colorado School of Mines)
2. Dorgan, John R. (Colorado School of Mines)

Author and Affiliation Lines (in printed abstract book)
Nichoals A. Rorrer and John R. Dorgan
Colorado School of Mines, Golden, CO 80401

Speaker / Presenter 
Rorrer, Nichoals A.

Text of Abstract
The COMOFLO Algorithm is an adaptation of the Cooperative Motion Algorithm which simulates polymers as coarse grained segments on a fully occupied lattice between to athermal walls. The algorithm cooperatively rearranges the segments through small closed loops of cooperative motion, and under quiescent conditions captures the crossover from Rouse to reptation like dynamics. Flow is simulated by biasing the displacement of polymer segments depending on their location on the lattice. By implementing this biasing shear, parabolic, and extensional flow profiles can be obtained. In the case of extensional flow, a hyperbolic flow profile similar to that found in a four roller mill is implemented. The crossover from the unentangled to entangled state is once again captured in the scaling of the zero shear viscosity when the polymer melts are subject to shear flow. In addition, when the polymer melts are subject to extensional flow the extensional viscosity profile can be obtained. At low extension rates, the extensional viscosity is three times (3x) the zero shear viscosity, agreeing with experimental results and theoretical postulates. Polydispersity has been implemented into the simulations and is found to affect the rheological properties of mixtures. Polydisperse melts demonstrate a cross flow migration behavior when subject to parabolic flow. Finally the algorithm proves to be capable of capturing the molecular scale details of slip. When subject to parabolic flow, all polymers exhibit signs of slip and when subject to shear flow the polymer melts exhibit signs of cohesive failure at high shear rates. The COMOFLO algorithm proves to be capable of capturing the correct rheological properties of polymer melts and offers fundamental insight into the molecular scale details of elusive phenomena, such as slip and cross flow migration.