TY  - JOUR
AU  - Tartaglino, U.
AU  - Sivebaek, I. M.
AU  - Persson, B. N. J.
AU  - Tosatti, E.
TI  - Impact of molecular structure on the lubricant squeeze-out between curved surfaces with long range elasticity
JO  - The journal of chemical physics
VL  - 125
SN  - 0021-9606
CY  - Melville, NY
PB  - American Institute of Physics
M1  - PreJuSER-53859
SP  - 014704
PY  - 2006
N1  - Record converted from VDB: 12.11.2012
AB  - The properties of butane (C4H10) lubricants confined between two approaching solids are investigated by a model that accounts for the curvature and elastic properties of the solid surfaces. We consider the linear n-butane and the branched isobutane. For the linear molecule, well defined molecular layers develop in the lubricant film when the width is of the order of a few atomic diameters. The branched isobutane forms more disordered structures which permit it to stay liquidlike at smaller surface separations. During squeezing the solvation forces show oscillations corresponding to the width of a molecule. At low speeds (<0.1 ms) the last layers of isobutane are squeezed out before those of n-butane. Since the (interfacial) squeezing velocity in most practical applications is very low when the lubricant layer has molecular thickness, one expects n-butane to be a better boundary lubricant than isobutane. With n-butane possessing a slightly lower viscosity at high pressures, our result refutes the view that squeeze-out should be harder for higher viscosities; on the other hand our results are consistent with wear experiments in which n-butane were shown to protect steel surfaces better than isobutane.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:16863321
UR  - <Go to ISI:>//WOS:000238849500042
DO  - DOI:10.1063/1.2210008
UR  - https://juser.fz-juelich.de/record/53859
ER  -