title: Effective viscosity of confined hydrocarbons.
abstract: We present molecular dynamics friction calculations for confined hydrocarbon films with molecular lengths from 20 to 1400 carbon atoms. We find that the logarithm of the effective viscosity η(eff) for nanometer-thin films depends linearly on the logarithm of the shear rate: log η(eff)=C-nlog ̇γ, where n varies from 1 (solidlike friction) at very low temperatures to 0 (Newtonian liquid) at very high temperatures, following an inverse sigmoidal curve. Only the shortest chain molecules melt, whereas the longer ones only show a softening in the studied temperature interval 0<T<900 K. The results are important for the frictional properties of very thin (nanometer) films and to estimate their thermal durability.
authors.affiliation: IFF, FZ-Jülich, 52425 Jülich, Germany.
authors.forename: I M
authors.initials: IM
authors.lastname: Sivebaek
authors.forename: V N
authors.initials: VN
authors.lastname: Samoilov
authors.forename: B N J
authors.initials: BN
authors.lastname: Persson