New developments in the field of synthetic lubricants from natural sources

Oils derivedfrom natural sources like vegetable and animal fats are constituted by a variety of triglycerides. The major drawbacks as compared to petroleum lubricants is poor stability under operating conditions, caused by (1) presence of β-hydrogen in the glyceride radical; (2) unsaturation in acyl radicals, which is linked to hydroxide formation and oxidation stability; (3) linear structure of the fatty acid which has poor resistance to hydrolysis and emulsification. There are several reactions in oleochemistry by which the structure of triglycerides could be modified, and so liquids with good lubrication properties produced. These include hydrogenation, dimerization, alkylation, polyol formation and transesterification. This paper deals with the application of transesterfication for the modification of the glyceride structure into a lubricant. This permits preparation of a semisynthetic lubricant directly from natural glycerides. Molecular structure, molecular weight, polarity, rheological properties, thermal and hydrolytic stability of transesterification products are reported.