Examining the rheology of 9-octylheptadecane to giga-pascal pressures

The properties of alkanes in the C-20-C-40 mass range are of fundamental importance in industrial applications as they are important constituents of synthetic lubricant base stocks. In an extension to earlier work on alkanes in the C-20-C-40 carbon number range we present the results of molecular simulations for 9-octylheptadecane, a starlike isomer of C-25 Both equilibrium (EMD) and nonequilibrium molecular dynamics (NEMD) simulations have been performed under ambient state conditions and to pressures in the gigapascal range. The EMD simulations focus on calculations of the rotational relaxation times, while the NEMD simulations reveal the dependence of the viscosity on strain rate. Additionally, we calculate the viscosity number and pressure-viscosity coefficient for 9-octylheptadecane and compare the results with those obtained experimentally. (C) 2001 American Institute of Physics.