History-Dependent Stress Relaxation of Liquids under High-Confinement: A Molecular Dynamics Study

When liquids are confined into a nanometer-scale slit, the induced layering-like film structure allows liquid to sustain non-isotropic stresses and thus be load-bearing. Such anisotropic characteristics of under confinement arise naturally from liquids’ wavenumber dependent compressibility, which does not need solidification take place as prerequisite. In other words, can still retain fluidity with molecules being (sub-)diffusive. However, extensively prolonged structural relaxation times cause hysteresis stress in response motions confining walls thereby rendering quasi-static tensors history-dependent. this work, by means molecular dynamics, highly key base-oil component, i.e., 1-decene trimer, calculated after its compressed decompressed. A maximum 77.1 MPa normal discrepancy has been detected within triple-layer boundary film. Analyses respect morphology indicate that among effects (e.g., confinement, structure, density) potentially affect stresses, ordering status plays predominant role.