The Effect of Long-chain and Branched Alcohol on Lubricity of Dodecanedioic Acid Based Ester

Thirteen samples of esters based on dodecanedioic acid with different chemical structures were synthesized. Among these were di-2-octyl dodecanedioate, didecyl dodecanedioate, di-2-ethylhexanol dodecanedioate, di-2-ethylbutyl dodecanedioate, dioctyl dodecanedioate, dihexyl dodecanedioate, and dioleyl dodecanedioate. Diesters were synthesized through the esterification of dodecanedioic acid with selected long-chain and branched alcohols with acid catalyst of H2SO4. These esters were tested in terms of their suitability for application as lubricants. The results showed that the lubricity properties, based on their pour point, flash point, and oxidation stability of the esters were significantly affected by the linear and branched alcohols used. An excellent pour point property of di-2-ethylbutyl dodecanedioate and di-2-ethylhexanol dodecanedioate at −55 °C and −50 °C was observed compared to their respective same linear carbon number esters of dihexyl dodecanedioate at 10 °C and dioctyl dodecanedioate at 20 °C. These are due to the presence of the branched group in their molecule vicinity structure. However, the esters flash points were insignificantly affected by the presence of branched structure. The selected esters could be used for biolubricants or engine oil.