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Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Melt fracture of entangled polymers
1Institut Curie, Centre de Recherche, 26, rue d'Ulm, 75005 Paris, France.
The European Physical Journal. E, Soft Matter
|June 5, 2007
Summary
A new model explains melt slippage at solid surfaces, driven by chain entanglement and shear forces. This phenomenon, crucial for understanding melt fracture, occurs at critical stresses, aligning with experimental observations.
Area of Science:
- Polymer Physics
- Materials Science
- Rheology
Background:
- Melt fracture is a common phenomenon in polymer processing.
- Understanding the mechanisms of melt slippage is crucial for controlling polymer flow behavior.
- Existing models do not fully capture the conditions leading to slippage.
Purpose of the Study:
- To develop a theoretical model for slippage planes in sheared polymer melts.
- To investigate the role of reptation bridging and shear debonding in melt slippage.
- To identify the conditions and locations where slippage is likely to occur.
Main Methods:
- Constructed a theoretical model balancing reptation bridging and shear debonding.
- Analyzed the stability of the proposed slippage state.
- Proposed slippage occurs at solid/melt interfaces (container walls or particles).
- Estimated the critical stress for slippage.
Main Results:
- The model predicts a locally stable slippage state at low shear rates.
- Nucleation of this state is difficult due to the stability of the entangled state.
- Slippage is proposed to occur at solid/melt interfaces.
- A critical stress (sigma*) for slippage was estimated to be approximately 1/3 of the plateau modulus for strong adsorption.
Conclusions:
- The model provides a framework for understanding melt slippage and its relation to melt fracture.
- Slippage at solid interfaces is a key factor in observed melt fracture phenomena.
- The estimated critical stress aligns with experimental observations of melt fracture at moderate stresses.
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