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Molecular Entanglement and Electrospinnability of Biopolymers
Published on: September 3, 2014
Molecular dynamics simulations of polymer welding: strength from interfacial entanglements
Ting Ge1, Flint Pierce, Dvora Perahia
1Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Physical Review Letters
|March 19, 2013
Summary
Polymer welding simulations reveal interfacial strength reaches bulk levels before full diffusion. Sufficient entanglements, not diffusion, drive strength and change failure modes from pullout to scission.
Area of Science:
- Materials Science
- Polymer Science
- Computational Materials Science
Background:
- Thermal welding is crucial for polymer integration and self-healing.
- Developing interfacial strength equal to bulk properties is essential for applications.
- Understanding the mechanisms of strength development is key.
Purpose of the Study:
- To investigate the development of mechanical strength at polymer-polymer interfaces during thermal welding.
- To determine the relationship between welding time, polymer diffusion, and interfacial strength.
- To identify the role of chain entanglements in interfacial strength and failure modes.
Main Methods:
- Large-scale simulations of polymer thermal welding.
- Tracking polymer diffusion by radius of gyration.
- Analyzing interfacial entanglements using primitive path analysis.
Main Results:
- Interfacial strength saturates at bulk shear strength before polymers reach their radius of gyration.
- The dominant failure mode shifts from chain pullout to chain scission with increasing strength.
- Interfacial strength increase is proportional to the number of interfacial entanglements.
- Bulk mechanical response is recovered when interfacial entanglement density matches the bulk value.
Conclusions:
- Sufficient interfacial entanglements, not polymer diffusion, are critical for achieving bulk-like mechanical strength.
- Entanglements arrest catastrophic chain pullout, enabling strength comparable to the bulk material.
- The density of entanglements across the interface dictates the recovery of bulk properties.
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