Evaluation of renewable feedstock-derived copolymers of stearyl methacrylate-co-triglyceride as multifunctional green additives in lubricant

Abstract

The greener additives synthesized from bio-sources with low-cost and multifunctional applications have attracted considerable attention in the field of lubricant industry. In this study, the synthesis of novel multifunctional green additives of stearyl methacrylate-co-triglyceride polymeric architectures MGA-1 and MGA-2 has been reported by incorporating the stearyl methacrylate on the sunflower oil and soybean oil, respectively. Direct polymerization through the double bonds of the fatty acid chain in the presence of a free radical initiator leads to the formation of ecofriendly copolymeric additive. The synthesized copolymers have been characterized by routine spectroscopic analysis, and the molecular weight and thermal decomposition of copolymers were determined by gel permeation chromatography and thermogravimetric analysis, respectively. The rheological behavior and performance evaluation of the formulated base oil were examined in different concentrations of additive viz. 1%, 1.5%, and 2% (w/v). Both MGA-1 and MGA-2 additives act as pour point depressant, viscosity modifier, viscosity index (VI) improver, and rheology modifier to the base oil. However, MGA-1 additive acts as an excellent viscosity modifier and VI improvers, whereas MGA-2 copolymer acts as better pour point depressant (PPD). The rheological study established the shear-thickening behavior for both the additive. The significance of this study lies in the fact that the increment in viscosity occurs with shear rate which make the formulated lubricant feasible at extreme conditions. Along with this, these vegetable oils derived additives MGA-1 and MGA-2 can be considered as good alternative to conventional synthetic homo- and copolymeric lubricant additives for environmentally benign lubricant formulations.