Rheological and tribological approaches as a tool for the development of sustainable lubricating greases based on nano-montmorillonite and castor oil

Abstract

This study investigates the development of novel montmorillonite/castor oil blends to formulate sustainable lubricating greases to promote the replacement of petrochemicals industry-derived materials by substances obtained from renewable sources. Specifically, the effect of the thickener concentration on the rheological, chemical, thermal, tribological properties, and atomic force microscopy (AFM) microstructure of these systems were studied. The results showed that the C20A nanoclay content could be used to modulate the viscosity values, the linear viscoelastic functions, and tribological properties of these montmorillonite dispersions. In general, these gel-like dispersions exhibited remarkable lubricant properties; the samples showed values of the friction coefficient and wear scars similar or lower than those obtained with model bentonite grease.

Synthesis of Layered Octadecyltrimethylammonium-Templated Aluminosilicate and its Use as a Thickening Agentfor Lubricating Grease

“…As shown in Figure 3, the values of G' and G'' for the LS gels remained constant over a wide range of strain amplitudes, indicating that both of these gels had a relatively wide LVR. This viscoelastic behavior is similar to that previously reported for gel-like dispersions [28][29][30][31]. Compared with LS(0) gel, the storage modulus (G') of LS(0.20) gel was found to be about 8.2 times higher.…”

Investigation of the Interaction, Rheological and Tribological Properties of Bis(pinacolato)diboron with Lithium Grease

“…Similar behavior was observed for oleogel-like dispersions containing ethylene vinyl acetate copolymer (EVA) and higholeic sunflower (HOSO) vegetable oil [11]. The reason is that oleogels with lower viscosity and viscoelastic moduli are easier to generate a protective lubricating film in comparison with oleogels with higher viscosity and viscoelastic moduli [10]. Thanks to the good friction reduction and anti-wear (AW) properties, oxidation inhibition, and low toxicity, intensive research has been done on using borates as high-performance and eco-friendly lubricant additives [12][13][14], and their results indicated that the good tribological performance of borate is ascribe to the boundary lubrication film formed by borate esters adsorbed on the sliding surfaces and tribochemical reaction between borate esters and steel surfaces [14].…”

“…However, there is room to improve the mechanical stability (rheological parameters) and tribological properties of lubricating grease simultaneously, as increasing the rheological properties of grease usually do not prevent friction and wear reduction. For instance, the lubricating grease based on nano-montmorillonite and castor oil with higher thickener agent (commercial organo-montmorillonite Cloisite 20A) achieved higher friction coefficient at different normal loads (10 N and 30 N) [10]. Similar behavior was observed for oleogel-like dispersions containing ethylene vinyl acetate copolymer (EVA) and higholeic sunflower (HOSO) vegetable oil [11].…”

Impact of Vegetable Oil Type on the Rheological and Tribological Behavior of Montmorillonite-Based Oleogels

“…Since the double bonds in the fatty acid chains in vegetable oils quickly react with oxygen, and a high content of double bonds is found in vegetable oils, such as sunflower, soybean, olive, linseed, and palm. The development of oleogels to formulate eco-friendly semi-solid lubricants based on nanoclay such as sepiolite and organo-montmorillonite with castor and soybean oils have been reported [ 25 , 26 , 27 ]. Particularly, the effect of the thickener concentration on the rheological, chemical, thermal and tribological properties, of these systems have been studied.…”