Synergistic effect of ionic liquid on additive performance of octyl acrylate-vinyl acetate copolymer and their comparison when added to lube oil

Ionic liquids (ILs) have come out as a promising lubricant additive in base oil during the past few years due to their low volatility, non–flammability, thermal stability, moisture stability and miscibility with organic compounds. In the present work, an investigation was carried out to determine whether the flow improvement property and shear stability of a polymeric additive can be affected when blended with an ionic liquid. We prepared a copolymer of vinyl acetate and octyl acrylate and blended it with imidazolium–based IL. Their performance as pour point depressant (PPD), viscosity index improver (VII) and also their stability against the mechanical shear in terms of permanent shear stability index (PSSI) were determined when added to the base oil as solo additive or as blend. The results revealed that the blend outweighs the polymer and the IL in all respect as a lubricant additive. As PPD, the best result was obtained in case of the blend at 4% concentration in both the base oils i.e. –12.1 °C and –13.7 °C in BO1 and BO2 respectively. Kinematic viscosity loss was least when the base oils were doped with the blend. This was supported by the PSSI data: 24.22 at 1% concentration in BO1 and 11.82 at 3% concentration in BO2.