Phosphonitrogenated methyl epoxyoleate as sustainable bio-based lubricating additive for paraffin oil and vegetable oil

Phosphonation and nitrogenation of methyl epoxyoleate (MEO) were done to prepare phosphonitrogenated methyl epoxyoleate (PNMEO). The structural characteristics of PNMEO were characterized. The tribological properties of PNMEO and MEO as additives in a paraffin oil and a rapeseed oil were evaluated, and the morphologies, element compositions and tribochemical species of worn surfaces were analyzed. Results showed that PNMEO was more efficient in enhancing tribological properties of oils than MEO. Results also showed that PNMEO and MEO were more powerful in paraffin oil than in rapeseed oil in improving load-carrying, friction-reducing and anti-wear performances, but in rapeseed oil than in paraffin oil in improving extreme pressure property. The tribological mechanisms of PNMEO in reducing friction and wear were attributed to PNMEO-involved tribo-adsorptions and tribo-reactions to produce a composite boundary lubrication film which consisted of a matrix of PNMEO with inclusions of iron oxide, polyphosphates, aminic compounds, and the base oil molecules.