Paper Number
SM33 

Session
Polymer Solutions & Melts

Title
Melt extensional rheology: SER vs. FSR and internal energy buildup

Presentation Date and Time
February 15, 2017 (Wednesday) 1:30

Track / Room
Track 5 / Snowy Egret

Authors (Click on name to view author profile)

1. Lin, Panpan (University of Akorn)
2. Zhao, Z.C. (University of Akorn)
3. Liu, Jianning (University of Akron)
4. Wang, Zhen-Gang (Caltech)
5. Wang, Shi-Qing (University of Akorn)

Author and Affiliation Lines (in printed abstract book)
Panpan Lin¹, Z.C. Zhao¹, Jianning Liu¹, Zhen-Gang Wang², and Shi-Qing Wang^1
1University of Akorn, Akron, OH; ²Caltech, Pasadena, CA

Speaker / Presenter 
Wang, Shi-Qing

Text of Abstract
In this presentation, we discuss extensional rheological behavior of various polymer melts using either SER (Sentmanat Extensional Rheometer) or Instron. After discussing the physics behind the emergence of tensile strain localization, we provide evidence for lack of fully developed flow state in such a global extensional test. While SER ensures homogeneous extension until the onset of extensional failure, FSR (filament stretching rheometer) does the opposite by applying non-uniform extension. Thus, SER is to simple shear achieved in small gap approximation of parallel-plate displacement as FSR is to capillary extrusion that merely supplies a constant throughput. By monitoring the temperature of the specimens in melt extension, we detected a sizable level of internal energy that can be as high as a significant fraction of the total mechanical work. Moreover, the internal energy build-up continues monotonically until the onset of specimen breakup. We conclude that well-entangled melts cannot transform from the initial state of rubbery-like elastic deformation to a flow state in uniaxial extension, contrary to the claims based on the FSR measurements that a steady extensional flow state is accessible in uniaxial melt extension. Finally, we disclose additional evidence concerning the origin of the internal energy storage.