Self-diffusion in the compressed, highly viscous liquid 2-ethylhexyl benzoate

Abstract

The self-diffusion coefficients, densities, and viscosities of liquid 2-ethylhexyl benzoate are reported as a function of pressure from 1 to 4500 bar within the temperature range from -20 to +100/sup 0/C. The rough hard sphere (RHS) model and the Stokes-Einstein equation are used to analyze the data. The RHS model indicates a high degree of rotational-translational coupling which increases as density increases. The nonspherical shape and conformational flexibility of the molecule are proposed as the cause of this behavior. The Stokes-Einstein equation is found to hold over 5 order or magnitude changes in self-diffusion and viscosity.