Tribological, rheological, and microstructural characterization of oleogels based on EVA copolymer and vegetables oils for lubricant applications

This work deals with the development of oleogels based on conventional (SO) and high-oleic sunflower (HOSO) vegetable oils and ethylene–vinyl acetate copolymer (EVA) for lubricant applications. Particularly, the influence of EVA concentration on the tribological, rheological properties and microstructure of these oleogels was analyzed. The results showed that the evolution of linear viscoelasticity functions was similar to that found for lithium greases. The different fatty acid profile in vegetable oils tested exerted an important influence on friction and wear in the ball-on-plates contact. The friction coefficient values became lower when EVA content was decreased. The wear marks obtained after the frictional tests for EVA–SO oleogels significantly reduced the wear scars versus EVA–HOSO oleogels and it was similar to commercial grease.