Synergy of two fatty acids as additives on lubricity of a nematic liquid crystal 5CB

Tadokoro, Chiharu; Araya, Shoki; Watanabe, Megumi; Ōkubo, H.; Nakano, Ken; Sasaki, Shinya

doi:10.1002/ls.1406

Cited by 6 publications

(3 citation statements)

References 34 publications

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“…As both conventional neutral thermotropic LCs and fatty acid have shown their potential as lubricants or lubricant additives, very recently Tadokoro et al [28] have shown the synergistic effect that takes place when fatty acids are used as additives of a nematic cyanobiphenyl LC. The mixture affords lower friction coefficients than any of the lubricants when they are used separately.…”

Section: Fatty Acids and Other Combinations And Synergistic Effectsmentioning

confidence: 99%

Ionic Liquid Crystals in Tribology

et al. 2019

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The present work intends to provide a brief account of the most recent advances in the use of ionic liquid crystals (ILCs) in the field of tribology, that is, the development of new lubricants with the ability to reduce the coefficients of friction and the wear rates of materials under sliding conditions. After a definition of ILCs and their relationship with neutral liquid crystals (LCs) and ionic liquids (ILs), the review will be focused on the influence of molecular structure and composition on the tribological performance, the combination with base oils, surfactants or water, and the different sliding configuration and potential applications. The main mechanisms proposed in order to justify the lubricating ability of ILCs will be analyzed. Special emphasis will be made for recent results obtained for fatty acid derivatives due to their renewable and environmentally friendly nature.

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Section: Fatty Acids and Other Combinations And Synergistic Effectsmentioning

confidence: 99%

Ionic Liquid Crystals in Tribology

et al. 2019

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“…Fatty acids have been used as additives of neutral liquid crystals [30]. A synergistic effect was found, with friction coefficients lower than those of the separate lubricants.…”

Section: Introductionmentioning

confidence: 99%

Fatty Acid-Derived Ionic Liquid Lubricant. Protic Ionic Liquid Crystals as Protic Ionic Liquid Additives

Avilés¹,

Pamies²,

Sanes³

et al. 2019

Coatings

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Fatty acids are natural products which have been studied as green lubricants. Ionic liquids are considered efficient friction reducing and wear preventing lubricants and lubricant additives. Fatty acid-derived ionic liquids have shown potential as neat lubricant and additives. Protic ionic liquid crystals (PILCs) are protic ionic liquids (PILs) where cations and anions form ordered mesophases that show liquid crystalline behavior. The adsorption of carboxylate units on sliding surfaces can enhance the lubricant performance. Ionic liquid crystal lubricants with longer alkyl chains can separate sliding surfaces more efficiently. However, they are usually solid at room temperature and, when used as additives in water, transitions to high friction coefficients and wear rates, with tribocorrosion processes occur when water evaporation takes place at the interface. In order to avoid these inconveniences, in the present work, a protic ammonium palmitate (DPA) ionic liquid crystal has been added in 1 wt.% proportion to a short chain citrate ionic liquid (DCi) with the same protic ammonium cation. A spin coated layer of (DCi + DPA) was deposited on AISI316L steel surface before the sliding test against sapphire ball. Synergy between DCi PIL and DPA PILC additive reduces friction coefficient and wear rate, without tribocorrosion processes, as shown by scanning electron microscopy (SEM)/energy dispersive X-ray microanalysis (EDX) and X-ray photoelectron spectroscopy (XPS) results.

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“…1 They exhibit fluidity as liquid and elasticity of crystalline solid body in direction perpendicular to the flow. 2,3 The remarkable rheological properties of these materials are due to the flow-induced evolution of molecular configurations. 1 It was also established that liquid crystals can change their orientation state in the vicinity of a solid surface.…”

Section: Introductionmentioning

confidence: 99%

Tribological capabilities of chiral nematic liquid crystal additives in mineral motor oil

Mokšin

2014

Advances in Mechanical Engineering

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This article presents the results of experimental investigation of tribological properties of commercial mineral motor oil with chiral nematic (also known as twisted nematic or cholesteric) liquid crystal additives. Cholesteryl stearate and valerate (fatty acid cholesterol esters) liquid crystals were used as oil additives in investigation. Tribological experiments were performed using a block-on-disc-type tribo-test machine at constant experiment time and sliding velocity conditions. The load (contact pressure), concentration of liquid crystalline additive in oil and Rz roughness of steel–steel friction surfaces were taken as variable parameters. The mean coefficient of friction of steel–steel friction pair lubricated by oil with and without liquid crystal additives and near-contact temperature were taken as dependent variables. Regression equations were then derived for each lubricant and tribological efficiency of liquid crystals as oil additives was evaluated. It was established that coefficient of friction of steel–steel friction pair and near-contact temperature are reduced to about a half in the presence of liquid crystal additives. Results of tribological experiments show that tribological efficiency of liquid crystals as oil additives increases with increase in their molecular mass.

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Synergy of two fatty acids as additives on lubricity of a nematic liquid crystal 5CB

Cited by 6 publications

References 34 publications

Ionic Liquid Crystals in Tribology

Ionic Liquid Crystals in Tribology

Fatty Acid-Derived Ionic Liquid Lubricant. Protic Ionic Liquid Crystals as Protic Ionic Liquid Additives

Tribological capabilities of chiral nematic liquid crystal additives in mineral motor oil

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