Article
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History-dependent Stress Relaxation of Liquids Under High-confinement: A Molecular Dynamics Study
Version 1
: Received: 1 November 2021 / Approved: 3 November 2021 / Online: 3 November 2021 (14:56:25 CET)
A peer-reviewed article of this Preprint also exists.
Gao, H. History-Dependent Stress Relaxation of Liquids under High-Confinement: A Molecular Dynamics Study. Lubricants 2022, 10, 15. Gao, H. History-Dependent Stress Relaxation of Liquids under High-Confinement: A Molecular Dynamics Study. Lubricants 2022, 10, 15.
Abstract
When liquids are confined into nanometer-scale slit, the induced layering-like film structure allows the liquid to sustain non-isotropic stresses and thus being load-bearing. Such anisotropic characteristics of liquid under confinement arise naturally from the liquids’ wave number dependent compressibility that does not need solidification to take place as a prerequisite. In other words, liquids under confinement can still remain fluidity with molecules being (sub-)diffusive. However, the extensively prolonged structural relaxation time can cause hysteresis of stress relaxation of confined molecules in response to the motions of confining walls and thereby yield the quasi-static stress tensor history-dependent. In this work, by means of molecule dynamics, the discrepancy of stress tensor of a highly confined key base-oil component, i.e. 1-decene trimer, is captured after its relaxation from being compressed and decompressed. The results indicate that among the effects (e.g. confinement, molecular structure, and film density) that can potentially affect confined stress tensor, the ordering status of the confined molecules plays a predominant role.
Keywords
Liquids; Confinement; Stress Relaxation; Molecular Dynamics; Hysteresis
Subject
Chemistry and Materials Science, Surfaces, Coatings and Films
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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