Tribological Properties of Vegetable Oils Modified by Reaction with Butanethiol

Abstract

Corn, canola, and castor-lauric estolide oils were chemically modified by photochemical direct reaction of butanethiol with the double bonds on the hydrocarbon chains. The effect of chemical modifications on viscosity, viscosity index (VI), pour point (PP), cloud point (CP), oxidation stability (RPVOT), 4-ball anti-wear (AW), and extreme pressure (EP) were investigated. The sulfide modified (SM) corn and canola oils showed increased viscosity, increased RPVOT time (more than one order of magnitude), reduced PP (9-18°C), and reduced VI. The SM estolide displayed similar trends in VI and RPVOT but showed no change in viscosity or cold flow. The SM oils, along with commercial mono-and polysulfide additives were also investigated as additives, at 0.6% (w/w) S concentration, in corn and polyalphaolefin (PAO) base fluids. In both fluids, the additives resulted in minor changes of PP, CP, coefficient of friction, wear scar diameter (WSD), and weld point (WP). Only the commercial polysulfide EP additive displayed large WP increases in the fluids. The additives resulted in no change of oxidation stability of corn oil, but displayed big improvement in the oxidation stability of PAO (8 to 16-fold increase in RPVOT time). The difference in the effect of the additives on the oxidation stability of PAO versus corn oil was attributed to the difference in the reactive hydrogen contents in the two base fluids relative to those in the additives. An empirical equation, for correlating change in RPVOT time with change in bond dissociation energy of reactive protons before and after chemical modification, is proposed.

Lubricants from renewable energy sources – a review

“…Thioether hydroxy vegetable oil was synthesized using a chemical reaction of epoxidized vegetable oil and common thiols (92) (Figure 9).…”

“…Chemical modification of vegetable oils (corn, canola, and castor-lauric estolide oils) by reaction with butanethiol was reported by Biresaw et al (92). Moreover, the effect of chemical modifications on viscosity, viscosity index, pour point, cloud point, oxidation stability, four-ball antiwear, and extreme pressure was also analyzed.…”

Estudio Comparativo del Poder Lubricante y Estabilidad Oxidativa entre el Aceite de Ajonjolí y Aceite Mineral 360

“…Por acción de la luz, la temperatura y el oxígeno, estos sitios activos son muy susceptibles al ataque de radicales, y forman compuestos oxigenados polares que resultan en depósitos insolubles y en el aumento de la acidez, la corrosión, la viscosidad y la volatilidad del aceite (Bart et al, 2013;Sharma et al, 2007). Sin embargo, el mejoramiento de las propiedades térmicas y lubricantes de los aceites vegetales se puede lograr mediante modificaciones químicas tales como epoxidación, transesterificación o hidrogenación selectiva (Biresaw et al, 2011;Alves et al, 2013) y el uso de aditivos de tipo antioxidante, detergente, dispersante, de extrema presión o anti-desgaste (Guala et al, 2009;Sharma et al, 2007;Minami et al, 1998).…”

Tribological properties of molybdenum disulphide nanoparticles in soybean oil

“…17 Thus, some studies were focused on the tribological properties of vegetable oils and the modification for improving their chemical stability. 18,19 A previous study investigated the effect of MoS 2 morphology on the tribological properties of rapeseed oil. 20 The results showed that the MoS 2 nanoplatelets remarkably increase the wear of friction pairs in rapeseed oil.…”

“…The chemical composition affects the tribological properties of vegetable oils. 19 The present study investigated the lubricating performance of MoS 2 with different morphologies (hollow nanospheres, nanoplatelets, and microplatelets) in soybean oil (SO). MoS 2 hollow nanospheres remarkably improved the lubricating performance of SO at 1?0 wt-% and revealed potential applications in SO.…”