Theory of the effect of external stress on the activated dynamics and transport of dilute penetrants in supercooled liquids and glasses
Journal Article
·
· Journal of Chemical Physics
- University of Illinois at Urbana-Champaign, IL (United States); Univ. of Illinois at Urbana-Champaign, IL (United States)
- University of Illinois at Urbana-Champaign, IL (United States)
We generalize the self-consistent cooperative hopping theory for a dilute spherical penetrant or tracer activated dynamics in dense metastable hard sphere fluids and glasses to address the effect of external stress, the consequences of which are systematically established as a function of matrix packing fraction and penetrant-to-matrix size ratio. All relaxation processes speed up under stress, but the difference between the penetrant and matrix hopping (alpha relaxation) times decreases significantly with stress corresponding to less time scale decoupling. A dynamic crossover occurs at a critical “slaving onset” stress beyond which the matrix activated hopping relaxation time controls the penetrant hopping time. This characteristic stress increases (decreases) exponentially with packing fraction (size ratio) and can be well below the absolute yield stress of the matrix. Below the slaving onset, the penetrant hopping time is predicted to vary exponentially with stress, differing from the power law dependence of the pure matrix alpha time due to system-specificity of the stress-induced changes in the penetrant local cage and elastic barriers. An exponential growth of the penetrant alpha relaxation time with size ratio under stress is predicted, and at a fixed matrix packing fraction, the exponential relation between penetrant hopping time and stress for different size ratios can be collapsed onto a master curve. Direct connections between the short- and long-time activated penetrant dynamics and between the penetrant (or matrix) alpha relaxation time and matrix thermodynamic dimensionless compressibility are also predicted. The presented results should be testable in future experiments and simulations.
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
- Grant/Contract Number:
- SC0020858
- OSTI ID:
- 1853677
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 5 Vol. 155; ISSN 0021-9606
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Activated penetrant dynamics in glass forming liquids: size effects, decoupling, slaving, collective elasticity and correlation with matrix compressibility
Self-consistent hopping theory of activated relaxation and diffusion of dilute penetrants in dense crosslinked polymer networks
Journal Article
·
Mon Feb 01 19:00:00 EST 2021
· Soft Matter
·
OSTI ID:1781783
Self-consistent hopping theory of activated relaxation and diffusion of dilute penetrants in dense crosslinked polymer networks
Journal Article
·
Wed May 10 20:00:00 EDT 2023
· Journal of Chemical Physics
·
OSTI ID:3012317