Paper Number
SM27 

Session
Polymer Solutions and Melts

Title
Strain hardening in startup shear

Presentation Date and Time
October 7, 2014 (Tuesday) 4:25

Track / Room
Track 3 / Commonwealth C

Authors (Click on name to view author profile)

1. Liu, Gengxin (University of Akron, Polymer Science)
2. Wang, Mengchen (University of Akron, Polymer Science)
3. Wang, Shi-Qing (University of Akron)

Author and Affiliation Lines (in printed abstract book)
Gengxin Liu¹, Mengchen Wang¹, and Shi-Qing Wang^2
1Polymer Science, University of Akron, Akron, OH 44325; ²University of Akron, Akron, OH

Speaker / Presenter 
Liu, Gengxin

Text of Abstract
The idea to treat entangled polymer solutions and melts as transient solids has allowed us to unify shear and extensional rheology that is often worked on by different sub-communities. Yielding of the entanglement network is a common thread because it occurs in both shear and extension, rheometrically manifested as shear stress and engineering stress overshoots respectively. Shear and extension are also sometimes different: at the same rate, shear produces yielding through chain disentanglement, signified a stress overshoot (strain softening); but extension can produce true strain hardening [1]. On the other hand, we already know that it is not true for polymers with long chain branching [2]. This work examines whether it is always true that strain hardening never occurs in startup shear. This work is supported, in part, by NSF (DMR-1105135). [1] Shear and extensional rheology of entangled polymer melts: Similarities and differences, Sci. China – Chem. 55, 779 (2012). [2] Strain hardening in startup shear of long-chain branched polymer solution, Phys. Rev. Lett. 111, 068302 (2013).