Elastohydrodynamic properties of seed oils

The film-forming properties of canola (CAN), soybean (SBO), and jojoba (JO) seed oils under elastohydrodynamic (EHD) conditions were investigated to determine whether differences in their chemical and physical properties affect their EHD properties. Polyalphaolefin (PAO), whose EHD properties have been reported before, was used as the reference synthetic oil. The effect of measurement variables (speed, load, and temperature) on the film thickness of seed oils was consistent with that predicted by EHD theory. Pressure-viscosity coefficients (pvc) calculated from film thickness data at 40 degrees C showed a steady-state value until about 50 nm film thickness, from which the following mean and SD values for CAN, SBO, and JO were obtained (GPa(-1)): 10.0 +/- 0.9, 7.6 +/- 0.7, and 7.3 +/- 0.5, respectively. However, further reduction of film thickness below about 50 nm resulted in an increase of pvc for CAN, but a decrease of pvc for SBO and JO.