| Abstract: | Esters for lubrication can be classified into two major groups. One is the neopentyl type or the so‐called hindered type. The other is the triglyceride type, which includes vegetable oils. The improvement of the antiwear properties of carboxylic esters by additive technology under boundary lubrication conditions is studied in this paper. Two strategies are considered, based on the structure of the esters. Triglyceride‐type esters are mainly used as rapidly biodegradable fluids. They have carbon‐carbon unsaturated bonds in their molecules, which are susceptible to auto‐oxidation, and this auto‐oxidation has deleterious effects on the antiwear properties. A synergistic effect of antioxidants and antiwear additives on wear reduction was observed. The mechanism is discussed and practical solutions proposed. Neopentyl‐type esters have thermal and oxidative stability. For these oils, the antiwear properties depend on the polarity of the additive and base oil. The effect of molecular structure on the antiwear properties is discussed. Computer simulation is used to understand the mechanism of action. Examples of molecular design of antiwear additives for neopentyl‐type esters are also proposed. |
