Capacity of thiourea Schiff base esters as multifunctional additives: synthesis, characterization and performance evaluation in polyol

A novel thiourea Schiff base ester TSBE was synthesized following a two step reaction. At first, thiourea and salicylaldehyde were reacted in ethanol to obtain thiourea Schiff base TSB. In the second step, esterification of TSB was done with lauroyl chloride catalyzed by 4-(dimethylamino)pyridine (DMAP) in N,N-dimethylacetamide (DMAc) solvent to obtain the final product TSBE. The synthesized compounds were characterized using CHN analysis, FT-IR and NMR. The antioxidant properties of this additive were assessed via the universal oxidation test (IP-306) and rotary bomb oxidation test (ASTM D2272) while antifriction and antiwear properties were evaluated in terms of the average friction coefficient and average wear scar diameter respectively by doing the four ball test (ASTM D4172). Studies revealed that TSBE had good antioxidant properties. Tests carried out by a four ball test machine indicated that the additive TSBE could reduce the friction to 45.6% and wear to ∼20% when compared with the pure polyol base oil.

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