Terpolymers based on sunflower oil/alkyl acrylate/styrene as sustainable lubricant additive

Abstract

Five terpolymers consisting of an alkyl acrylate (octyl acrylate/decyl acrylate/dodecyl acrylate), sunflower oil and styrene in different ratios (w/w) viz. 1:1:1, 2:1:1 and 3:1:1 were synthesized by free radical polymerization method using azobisisobutyronitrile (AIBN) initiator in toluene solvent. The polymers were characterized by FT-IR and NMR spectroscopy. Molecular weight of the prepared polymers was determined by gel permeation chromatography (GPC) method. Thermal stability of the polymers was determined by thermogravimetric analysis (TGA). Performance of the prepared polymers as viscosity modifier (VM), also known as viscosity index improver (VII), pour point depressant (PPD) and antiwear in different base oils were evaluated according to standard ASTM methods. Photo micrographic image were used to study the action mechanism of the additives as PPD. Biodegradability of all the polymers was tested through disc diffusion method. From the experimental results, it was observed that the ratio 2:1:1 is most effective for the preparation of terpolymers based on acrylate, sunflower oil and styrene. Moreover, it is also observed that efficiencies as VII and antiwear increase but PPD decrease with increasing the alkyl chain length of the prepared polymers.