Lubricant basestocks from vegetable oils

Compared to the lubricants made of petroleum, vegetable-based lubricants ar e much more biodegradable but inferior in many other technical characterist ics. The basestock typically contributes to more than 80% of lubricant and must meet performance criteria in such aspects as cleanliness, viscometric properties, volatility, oxidative and hydrolytic stability, deposit forming tendencies, solvency, miscibility or compatibility with system elastomers and other. For vegetable-based lubricants, oxidative stability and low temp erature problems are considered the most critical. Thin film oxidation test was used to compare oxidative stabilities. Vegetable oils appear an order of magnitude less stable than mineral oils or synthetic biodegradable bases tocks, such as isoalkyl adipates or poly alphaolefins. Low temperature perf ormance of vegetable oils, namely pour points and cold storage, was also pr oblematic. These problems can only partially be relieved by lubricant addit ives, thus vegetable oils have to be modified chemically to eliminate sites susceptible to oxidation and to disrupt formation of crystals at low tempe ratures. Published by Elsevier Science B.V.