The surface forces apparatus (SFA) was used to study the lubricating properties of an 8CB liquid crystal
film confined between mica surfaces. After displacement of most of the liquid crystal by compression, a
10.2 Å thick layer of 8CB was found between mica surfaces in the range of applied pressures from 1 to
20 MPa. Under these conditions, we found that friction depends linearly on contact area in the 1−1.5 MPa
range. We found that the critical shear stress was anisotropic, with values of 0.28 MPa for shear along
the 8CB molecular axis and 0.42 MPa for shear in the perpendicular direction. This anisotropy was observed
through all the ranges of load where slip occurred. At higher loads (1.5−2.7 MPa), the critical shear
stresses increase to 0.6 and 1.2 MPa for parallel and perpendicular shear, respectively.
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