Study on synthesis of biodegradable polyurea grease using modified vegetable oil

Lubricants have been applied in numerous industrial fields, as they help reduce friction and heat generated when operating machines and also protect metallic parts in corrosive environments. In some applications, especially in marine, these greases need to be biodegradable, or they get accumulated and can be harmful to aquatic life. To address this matter, modified vegetable oil was used instead of persistent mineral oil. Also, in submerged conditions, polyurea grease outperforms traditional lithium grease as the latter is more susceptible to water washout. So, in this paper, the polyurea thickener was synthesized in-situ in biodegradable modified vegetable oil by using methylene diphenyl diisocyanate and amines as precursors. The fabricated grease chemical properties were determined by FTIR, and its tribological characteristics were studied by dropping point, penetration, and four-ball test. Results showed that polyurea grease has high operational temperature (dropping point at 278 oC), excellent pumpability (penetration 275 mm-1), and offers great wear resistance (wear load 233 kg).