High pressure rheology of lubricants is important to know the lubricating states of metalworking and bearings/gears in Elasto-Hydrodynamic Lubrication (EHL) region. In the previous report, I have derived the van der Waals liquid state equation, and applied it to estimate high pressure density. In addition, for three material-specific constants of lubricants included in this equation, which are absolute zero volume Vt=0, liquid constant RL, and compensation pressure PR for pressure drop by liquid intermolecular force, the data of various lubricants were collected. In this report, a multiple linear regression analysis was performed with above three material-specific constants as the objective variables and the physical properties /chemical-structures of lubricants as explanatory variables, and then a multiple regression equation was created. As a result, it was clarified that for unknown lubricants, three material-specific constants (Vt=0 mr-eq, RL mr-eq and PR mr-eq) in the van der Waals liquid state equation and the high pressure density ρmr-eq can be estimated only by analyzing the physical properties and chemical structures using this multiple linear regression equation, without measuring high pressure densities by experiments using a high-pressure density measuring device. The details of the results will be reported.
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