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Updated: Jul 3, 2026
06:55
Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Molecular physics of a polymer engineering instability: experiments and computation
D G Hassell1, M R Mackley, M Sahin
1Department of Chemical Engineering, University of Cambridge, Cambridge CB2 3RA, United Kingdom.
Summary
Flow instabilities in entangled polymer melts hinder industrial production. This study reveals a viscoelastic disturbance at the slit outlet, driven by chain stretch, offering insights into improving polymer processability.
Area of Science:
- Polymer physics
- Rheology
- Fluid dynamics
Background:
- Entangled polymer melts are prone to flow instabilities, limiting manufacturing efficiency.
- Understanding these instabilities is crucial for optimizing polymer processing.
Purpose of the Study:
- To investigate the formation and development of a specific flow instability in entangled polymer melts.
- To identify the underlying physical mechanisms and key parameters governing this instability.
Main Methods:
- Experimental flow of monodisperse linear polystyrenes in a contraction-expansion geometry.
- Computational linear stability analysis using the Rolie-Poly model.
Main Results:
- Observed a viscoelastic disturbance at the slit outlet, leading to upstream fluid motion.
- Confirmed the instability numerically and identified critical parameters.
- Determined that chain stretch plays a key role in the instability mechanism.
Conclusions:
- Chain stretch is a critical factor in polymer melt flow instabilities.
- This understanding can inform strategies to enhance polymer blend processability, such as incorporating low-molecular weight tails.
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