Paper Number
PO98 

Session
Poster Session

Title
Coil-stretch hysteresis in planar mixed flows of polymer solutions at finite concentrations

Presentation Date and Time
October 14, 2015 (Wednesday) 6:05

Track / Room
Poster Session / Atrium/Harborview

Authors (Click on name to view author profile)

1. Sasmal, Chandi (Monash University, Chemical Engineering)
2. Prakash, J. Ravi (Monash University, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Chandi Sasmal and J. Ravi Prakash
Chemical Engineering, Monash University, Melbourne, Victoria 3150, Australia

Speaker / Presenter 
Sasmal, Chandi

Text of Abstract
In 1974, de Gennes conjectured that in extension-dominated flows, depending on the deformation history, it is possible for a dilute polymer solution to manifest multiple values of stress at a single strain rate, and consequently exhibit hysteretic behaviour. The importance of de Gennes contention has paradigm changing implications for the modelling of polymer solution rheology. Experimental proof for de Gennes hypothesis was established 30 years later by showing individual DNA molecules in ultra-dilute solutions subjected to planar elongational flow can be either coiled or highly stretched depending on the history of deformation. While de Gennes arguments and the experimental validation were restricted to dilute solutions, recent scaling arguments and experiments carried out at Monash University suggest that the concentration of polymers has a significant non-monotonic influence on the extent of coil-stretch hysteresis. Additionally, it has been known since de Gennes early theory, that increasing the fraction of shear in a mixed flow of planar shear and extension dramatically decreases the magnitude of coil-stretch hysteresis. We discuss the development of a mesoscopic Brownian dynamics simulation algorithm that is capable of accurately describing polymer solutions undergoing planar mixed flows at finite polymer concentrations. The simulations permit the examination of the competing roles of polymer concentration and flow mixedness on the extent of coil-stretch hysteresis, and provide a fascinating insight into the influence of non-linear phenomena on the molecular scale on macroscopic solution properties.