Oil Lubricant Tribological Behaviour Improvement Through Dispersion of Few Layer Graphene Oxide

Sarno, Maria; Senatore, Adolfo; Cirillo, Claudia; Petrone, Vincenzo; Ciambelli, Paolo

doi:10.1166/jnn.2014.8673

Cited by 53 publications

(30 citation statements)

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“…Several remarkable properties of graphene-oxide/reduced graphene-oxide (GO/rGO) make it an effective solid additive for liquid lubricants12345. These include low shear strength, high yield strength, chemical compatibility for dispersion in polar lubricants, and high thermal conductivity and an ecofriendly composition56.…”

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confidence: 99%

“…Optimization of oxygen functionality in GO/rGO is an important aspect for preserving the chemical stability of the structure while providing sustainable covalent/noncovalent interactions with the lubricant. Lubrication enhancement by GO/rGO additives was described by the formation of low-shear-strength graphene tribofilm by adsorption to metal surfaces1210. However, the lubrication mechanism was effective also without forming mechanically stable graphene tribofilms within the sliding interfaces11.…”

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confidence: 99%

“…The dispersion of GO/rGO additives in the blends can assist in such optimization. For example, GO was also used as additive to enhance the antiwear properties of a mineral oil using a dispersant2. The dispersion of GO/rGO depends on the polarity of the lubricant and the functional groups of the GO/rGO.…”

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Role of oxygen functional groups in reduced graphene oxide for lubrication

Gupta

Kumar

Panda

et al. 2017

Sci Rep

472

195

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Functionalized and fully characterized graphene-based lubricant additives are potential 2D materials for energy-efficient tribological applications in machine elements, especially at macroscopic contacts. Two different reduced graphene oxide (rGO) derivatives, terminated by hydroxyl and epoxy-hydroxyl groups, were prepared and blended with two different molecular weights of polyethylene glycol (PEG) for tribological investigation. Epoxy-hydroxyl-terminated rGO dispersed in PEG showed significantly smaller values of the friction coefficient. In this condition, PEG chains intercalate between the functionalized graphene sheets, and shear can take place between the PEG and rGO sheets. However, the friction coefficient was unaffected when hydroxyl-terminated rGO was coupled with PEG. This can be explained by the strong coupling between graphene sheets through hydroxyl units, causing the interaction of PEG with the rGO to be non- effective for lubrication. On the other hand, antiwear properties of hydroxyl-terminated rGO were significantly enhanced compared to epoxy-hydroxyl functionalized rGO due to the integrity of graphene sheet clusters.

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Role of oxygen functional groups in reduced graphene oxide for lubrication

Gupta

Kumar

Panda

et al. 2017

Sci Rep

472

195

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“…For this reason, several techniques have been implemented to increase the GO exfoliation degree. In particular, solvent-based exfoliation and thermal exfoliation techniques emerged as two preferred routes for this step [16][17][18][19] . [30][31][32][33] .…”

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confidence: 99%

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Baldino

Sarno

Cardea

et al. 2015

Ind. Eng. Chem. Res.

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(Stefano Cardea) Phone Number: +39089969365; msarno@unisa.it (Maria Sarno) Phone Number: +39089964057.KEYWORDS: Graphene oxide, Cellulose acetate, Nanocomposite, Supercritical CO 2 . ABSTRACTCellulose acetate (CA)/graphene oxide (GO) nanocomposite membranes were generated by an assisted phase inversion process, based on the use of SC-CO 2 as non-solvent, operating at 200 bar and 40 °C; loadings of GO up to 9% w/w were tested. The structures maintained the cellular morphology, characteristics of CA membranes, also at the highest GO loadings used, with a porosity of about 80%, but the presence of GO influenced the pore sizes, that ranged between about 9 and 16 µm. The starting GO and the nanocomposite structures were characterized by the combination of various techniques that evidences as Sulphur and Chlorinated impurities, that were present in the starting GO material, were completely eliminated by the interaction with SC-CO 2 during structures formation; moreover, a partial reduction of GO to graphene was also observed. . Compared to graphene, GO is heavily oxygenated and its basal plane carbon atoms are decorated with epoxide and hydroxyl groups and its edge atoms with carbonyl and carboxyl groups. Hence, GO is highly hydrophilic and the presence of these functional groups reduces interplanar forces, which can improve the interfacial interaction between GO and some polymers and, thus, the dispersion of GO in polymer matrices 2,3 . Many factors can affect the final properties and applications of GO/polymer nanocomposites 4 , among these: kind of GO used, its dispersion state in the polymeric matrix and interfacial interactions, the amount of wrinkling, its network structure in the matrix and its purity.Various attempts have been proposed in the literature to realize GO/polymers composite structures [5][6][7][8][9][10][11][12][13][14][15] . The processes proposed until now (i.e., phase inversion, casting, electrospinning) present several limitations; for example, residues of organic solvents of GO synthesis are typically found at the end of these processes, causing problems, in particular, for biomedical applications. Moreover, a homogeneous distribution of GO in the polymeric matrix is difficult to obtain, since the cohesive forces among GO layers tend to produce restacking. GO composites performance is strongly related to its level of exfoliation (i.e., separation of the layers). Exfoliated GO allows the largest interfacial contact with the polymer matrix, improving the properties of the composites. For this reason, several techniques have been implemented to increase the GO exfoliation degree. In particular, solvent-based exfoliation and thermal exfoliation techniques emerged as two preferred routes for this step [16][17][18][19] . [30][31][32][33] . Due to molecular size of CO 2 and its polarizability, it has the potential to pass through the solid porous layers 34 and, when supercritical conditions are reached, CO 2 diffusivity can favor layers expansion and exfoliation [31][32][33] . It is also possible to...

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“…However, 2D materials must be stably dispersed when utilized in lubricating oil [66,67,68]. The fully structured 2D materials exhibit high chemical stability and van der Waals forces between layers and are thus prone to irreversible agglomeration.…”

Section: Field Of Lubricating Oilmentioning

confidence: 99%

Research Progress in Application of 2D Materials in Liquid-Phase Lubrication System

Liu

Zhou

Xiao³

et al. 2018

Materials

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Two-dimensional (2D) materials are ultra-thin crystals with layered structures that have a monolayer and multiple layers of atomic thickness. Due to excellent performance, 2D materials represented by graphene have caused great interest from researchers in various fields, such as nano-electronics, sensors, solar cells, composite materials, and so on. In recent years, when graphite was used for liquid phase lubrication, there have been many disadvantages limiting its lubrication properties, such as stable dispersion, fluidity and so on. Therefore, 2D materials have been used as high-performance liquid-phase lubricant additives, which become a perfect entry point for high-performance nano-lubricants and lubrication applications. This review describes the application of 2D materials as additives in the field of liquid-phase lubrication (such as lubricating oil and water lubrication) in terms of experimental content, lubrication performance, and lubrication mechanism. Finally, the challenges and prospects of 2D materials in the lubrication field were also proposed.

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Oil Lubricant Tribological Behaviour Improvement Through Dispersion of Few Layer Graphene Oxide

Cited by 53 publications

References 0 publications

Role of oxygen functional groups in reduced graphene oxide for lubrication

Role of oxygen functional groups in reduced graphene oxide for lubrication

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Research Progress in Application of 2D Materials in Liquid-Phase Lubrication System

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Oil Lubricant Tribological Behaviour Improvement Through Dispersion of Few Layer Graphene Oxide

Cited by 53 publications

References 0 publications

Role of oxygen functional groups in reduced graphene oxide for lubrication

Role of oxygen functional groups in reduced graphene oxide for lubrication

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO2 Assisted Phase Inversion

Research Progress in Application of 2D Materials in Liquid-Phase Lubrication System

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Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion