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Analysis of local properties during a scratch test on a polymeric surface using molecular dynamics simulations
1Institut Charles Sadron (UPR22-CNRS), University of Strasbourg, 23 rue du Loess, BP 84047, F-67034, Strasbourg, France. mathieu6707@sfr.fr
The European Physical Journal. E, Soft Matter
|March 26, 2013
Summary
This study links particle-based polymer behavior to continuum contact mechanics using molecular dynamics simulations. It reveals how polymer chain orientation and conformation influence friction during scratch tests.
Area of Science:
- Materials Science
- Polymer Physics
- Computational Mechanics
Background:
- Bridging particle-based (molecular) and continuum mechanics is crucial for understanding complex material behaviors.
- Polymer friction and contact mechanics are critical for applications ranging from lubrication to microelectronics.
- Molecular dynamics (MD) simulations offer a powerful tool to investigate phenomena at the nanoscale.
Purpose of the Study:
- To establish a connection between particle-level polymer dynamics and continuum mechanical theories of contact.
- To analyze polymer film behavior, including bond orientation, chain conformation, and stress fields, during simulated scratch tests.
- To investigate the influence of temperature, tip roughness, and tip-polymer interactions on scratch test outcomes.
Main Methods:
- Utilized molecular dynamics (MD) simulations to model scratch tests on linear amorphous polymer surfaces.
- Employed the second Legendre polynomial to quantify bond orientation and the gyration tensor to analyze chain conformation.
- Measured stress fields using the virial stress tensor within defined sub-boxes of the simulation cell.
Main Results:
- The second Legendre polynomial effectively captured bond orientation changes during sliding.
- Layer-resolved gyration tensor analysis provided insights into polymer chain conformation across the film thickness.
- Virial stress tensor measurements indicated a complex interplay of compressive hydrostatic pressure and shear stress at the interface.
- Results support Briscoe's hypothesis regarding thin film shearing versus bulk compressive behavior in polymer friction.
Conclusions:
- MD simulations can successfully link particle-level polymer behavior to continuum contact mechanics.
- Polymer chain conformation and orientation significantly influence frictional properties during tangential contact.
- The observed stress field suggests a complex sheared domain formation at the polymer-tip interface, validating theoretical hypotheses.
