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 im portance in industrial applications as they are important constituents of s ynthetic 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 si mulations for 9-octylheptadecane, a starlike isomer of C-25 Both equilibriu m (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 relaxat ion times, while the NEMD simulations reveal the dependence of the viscosit y on strain rate. Additionally, we calculate the viscosity number and press ure-viscosity coefficient for 9-octylheptadecane and compare the results wi th those obtained experimentally. (C) 2001 American Institute of Physics.