2014 年 59 巻 8 号 p. 507-514
Tribological performances of the oils containing polylaurylacrylates with and without hydroxyethyl group were studied under elastohydrodynamic lubrication (EHL), partial EHL and the boundary lubrication conditions. The base oil was polyalphaolefin and the viscosity of polymer solutions and the concentration of polymer was adjusted at the same level. Under the partial elastohydrodynamic contacts using a ball-on-disk type tribometer, polylaurylacrylatehydroxyethylacrylate (PLA/HEA) showed a greater oil film thickness while lower traction coefficient at low rolling speeds than polylaurylacrylate (PLA). This can be interpreted that adsorption of hydroxyethyl group of PLA/HEA reduced traction under the partial EHL condition. Under the boundary lubrication conditions using a pin-on-disk type tribometer, PLA/HEA exhibited the flat friction-velocity relation while PLA showed a large negative gradient of friction-velocity relation. Finally, PLA/HEA was superior to PLA in terms of the antiwear properties with a reciprocating friction tester. It is inferred that these better performances of PLA/HEA under the boundary lubrication conditions were brought about by formation of a tribofilm based on reaction of hydroxyethyl group and the sliding surface.
