Paper Number
SM31 

Session
Polymer Solutions and Melts

Title
Simple desktop calculations for slip-link predictions of entangled polymers

Presentation Date and Time
October 8, 2014 (Wednesday) 10:00

Track / Room
Track 3 / Commonwealth C

Authors (Click on name to view author profile)

1. Katzarova, Maria (Illinois Institute of Technology, Chemical and Biological Engineering)
2. Yang, Ling (Illinois Institute of Technology, Chemical and Biological Engineering)
3. Andreev, Marat (Illinois institute of Technology, Physics)
4. Schieber, Jay D. (Illinois Institute of Yechnology, Chemical and Biological Engineering)

Author and Affiliation Lines (in printed abstract book)
Maria Katzarova¹, Ling Yang¹, Marat Andreev², and Jay D. Schieber^1
1Chemical and Biological Engineering, Illinois Institute of Technology, Chicago, IL; ²Physics, Illinois institute of Technology, Chicago, IL 60616

Speaker / Presenter 
Katzarova, Maria

Text of Abstract
The discrete slip-link model (DSM) is a robust mesoscopic theory that has great success predicting the rheology of flexible entangled polymer liquids and gels. With just three parameters--the molecular weight of a Kuhn step M_K; entanglement activity; and Kuhn step friction--the DSM is able to predict simultaneously both nonlinear rheology and the linear viscoelasticity of monodisperse linear, polydisperse linear, branched, and cross-linked systems. Recently, we have proposed a hierarchy of slip-link models connected through successive coarse graining. Since the hierarchy is integrated, knowledge gleaned from a more-detailed level of description can inform a less-detailed one, or vice versa. In the most coarse-grained version of the DSM we exploit heavily the universality observed in the shape of the relaxation modulus of linear, monodisperse, entangled polymers. Furthermore, we present analytic expressions for the relaxation modulus of linear monodisperse melts. The glassy mode dynamics which are coarse-grained out from the DSM are added back into these expressions by using a Rouse chain with fixed ends to represent the fast motion of Kuhn steps between entanglements. We test these expressions against experimental data for a number of chemistries and molecular weights with good agreement. Using these analytic expressions, the polymer density, M_K, and the low-frequency cross-over between G' and G'', it is now very easy to estimate parameter values and obtain predictions over the experimentally accessible frequency range without performing numerical calculations. Additionally, the more coarse-grained version of the DSM has allowed a significant speed-up of the numerical calculations. For instance, a typical shear-flow experiment of say, polyisoprene with 30 entanglements, can now be calculated in seconds using a single graphics card on a desktop. Simultaneously, we have developed a graphical user interface to facilitate running simulations.