The Effect of Concentration, Solvent, and Temperature on Aggregation of a Commercial Calcium Sulfonate Additive as Studied by FTIR and Light Scattering Techniques

Sun, Jianxia; Hu, Zu-Shao; Hsu, Stephen M.

doi:10.1080/10402009708983702

Cited by 10 publications

(8 citation statements)

References 24 publications

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“…The recent development of in situ analyzers for solid–liquid interfaces is noteworthy and their application to tribological study is rapidly increasing in fact. Infrared (IR) spectroscopy had been commonly used since the early 1990s, − and attenuated total reflection infrared spectroscopy (ATR-IR) in particular has been used to obtain chemical information about adsorbed additive layers on substrate surfaces soaked in lubricant. − Infrared light can penetrate crystals made from silicon or germanium, so in situ analysis of the metal surface/lubricant interface is possible if thin metal film is first deposited onto the crystal surface. Another method that is increasingly being applied is sum frequency generation (SFG) spectroscopy, which also uses light, and its use has clarified the interfacial structure and molecular orientations of adsorbed additive layers. − Neutron reflectometry (NR) − and quartz crystal microbalance with dissipation monitoring (QCM-D) − are also useful for in situ evaluation of the thickness and density of adsorbed additive layers, and the combined use of these methods has led to further understanding of the boundary lubrication mechanism.…”

Section: Introductionmentioning

confidence: 99%

Cross-Sectional Imaging of Boundary Lubrication Layer Formed by Fatty Acid by Means of Frequency-Modulation Atomic Force Microscopy

Hirayama

Kawamura²,

Fujino³

et al. 2017

Langmuir

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To observe in situ the adsorption of fatty acid onto metal surfaces, cross-sectional images of the adsorption layer were acquired by frequency-modulation atomic force microscopy (FM-AFM). Hexadecane and palmitic acid were used as the base oil and typical fatty acid, respectively. A Cu-coated silicon wafer was prepared as the target substrate. The solvation structure formed by hexadecane molecules at the interface between the Cu substrate and the hexadecane was observed, and the layer pitch was found to be about 0.6 nm, which corresponds to the height of hexadecane molecules. This demonstrates that hexadecane molecules physically adsorbed onto the surface due to van der Waals forces with lying orientation because hexadecane is a nonpolar hydrocarbon. When hexadecane with palmitic acid was put on the Cu substrate instead of pure hexadecane, an adsorption layer of palmitic acid was observed at the interface. The layer pitch was about 2.5-2.8 nm, which matches the chain length of palmitic acid molecules well. This indicates that the original adsorption layer was monolayer or single bilayer in the local area. In addition, a cross-sectional image captured 1 h after observation started to reveal that the adsorbed additive layer gradually grew up to be thicker than about 20 nm due to an external stimulus, such as cantilever oscillation. This is the first report of in situ observation of an adsorbed layer by FM-AFM in the tribology field and demonstrates that FM-AFM is useful for clarifying the actual boundary lubrication mechanism.

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Section: Introductionmentioning

confidence: 99%

Cross-Sectional Imaging of Boundary Lubrication Layer Formed by Fatty Acid by Means of Frequency-Modulation Atomic Force Microscopy

Hirayama

Kawamura²,

Fujino³

et al. 2017

Langmuir

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“…The interfacial structure of this adsorption layer has been investigated in various studies over the past 30 or so years, and its state and behaviour have been gradually clarified, especially with the recent development of physical and chemical analyzers. For examples, infrared spectroscopy has been commonly used since the early 1990s, and attenuated total reflection infrared spectroscopy in particular has been used to obtain chemical information about adsorbed additive layers on substrate surfaces soaked in lubricant . Neutron reflectometry, quartz crystal microbalance with dissipation monitoring, and frequency‐modulation atomic force microscopy (FM‐AFM) have been applied to tribological surfaces and have been effectively utilised to facilitate understanding of the mechanisms of adsorption layers formed by oiliness additives.…”

Section: Introductionmentioning

confidence: 99%

Shear property of oil film containing oiliness additive in narrow gap measured with newly‐developed parallel‐disk viscometer supported by aerostatic bearing

Hirayama

Shibata

Harada

et al. 2019

Lubrication Science

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The shear force of oil film containing an oiliness additive in a narrow gap was measured with a newly developed parallel-disk viscometer supported by an aerostatic thrust bearing. To evaluate viscometer performance, the shear force of pure base oil was first measured using an oleophobic coated disk. Using the coated disk resulted in interfacial slip between the disk surface and oil, which significantly reduced the shear force compared with that when a noncoated disk was used. Next, the shear force of base oil containing an oiliness additive was measured without using the coated disk. Again it was significantly reduced, especially when the gap was less than 1 μm. The degree of reduction depended on the oiliness additive used. These results demonstrate that an oiliness additive can cause interfacial slip, resulting in friction reduction even in a hydrodynamic lubrication regime with a submicrometer gap. KEYWORDSinterfacial slip, narrow gap, oiliness additive, parallel-disk viscometer, shear property, thin oil film | INTRODUCTIONWith the strong demand for energy-conserving machines, usage of ultralow viscosity oil is rapidly becoming more common especially as engine oil for automobiles. The formed oil film is then thinner than that when high viscosity oil is used, reaching boundary lubricated state more easily. Then the additives mixed into the base oil have come to play a key role in achieving lower friction coefficients and higher wear durability for sliding surfaces. Particularly, oiliness additives generally form an adsorption layer on metal surfaces and thereby reduce friction, especially under lower pressure conditions in the boundary lubrication regime.Nomenclature: a, contact radius; c r0 , gap between the flat face of the outer ring area on the upper specimen and the lower disk; f 0 , shear force converted from f rot ; f b , pushing force by the air cylinder; f s , axial force generated in the aerostatic bearing; f rot , circumferential force measured by the load cell (6); h eq , equivalent gap in area 2 of the aerostatic bearing; h l , gap in area 3 of the aerostatic bearing; l, distance from the rotation centre to the pushing point of the load cell (6); p a , atmospheric pressure; p g , pressure at r g of the aerostatic bearing; p i (i=2,3), pressure in areas 2 and 3 of the aerostatic bearing; p s , inlet pressure for the aerostatic bearing; p ′ s , pressure at r s of the aerostatic bearing; r 0 , inner radius of the outer ring area on the upper specimen; r 1 , outer radius of the outer ring area on the upper specimen; r a , outer radius of area 3 of the aerostatic bearing; r g , outer radius of area 2 of the aerostatic bearing; r s , outer radius of inlet port of the aerostatic bearing; C, airflow contraction coefficient; E′, equivalent Young modulus; P max , maximum Hertz pressure; R, gas constant; T, temperature; δ, groove depth; γ, circumferential area ratio of the grooves; η, sample oil viscosity; η ap , apparent viscosity calculated from the measured shear force; κ, heat capacity ratio; μ, air visco...

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“…For NRHMS(10), the phase separation caused significant changes in the textural properties, providing a high surface area, but lower unit cell and pore wall thickness as less NR phase was incorporated within the silicate framework. In addition, its pore size was smaller than in the other NRHMS samples because the addition of the low H 2 SO 4 concentration led to an increased polarity of the synthesis mixture, which decreased the size of micelles due to a weakened interaction between the micelles themselves [44].…”

Section: Resultsmentioning

confidence: 99%

Facile fabrication of mesostructured natural rubber/silica nanocomposites with enhanced thermal stability and hydrophobicity

Chaowamalee

Ngamcharussrivichai

2019

Nanoscale Res Lett

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Natural rubber (NR)/hexagonal mesoporous silica (HMS) nanocomposites (NRHMS) with enhanced thermal and hydrophobic properties were facilely prepared via in situ sol–gel formation with pH adjustment using a low sulphuric acid (H2SO4) acid concentration. The effect of the amount of 0.5 M H2SO4 (2.5–10 g) added into the pre-synthesis mixture on the physicochemical properties of the obtained NRHMS nanocomposites was investigated. With a small addition of H2SO4 solution, the fabricated NRHMS nanocomposite possessed an improved wormhole-like mesostructure arrangement with a thicker silica wall, which retarded the thermal decomposition of the NR phase, as deduced from the auto-oxidation of NR by thermogravimetric analysis. The H2O adsorption–desorption measurement revealed an increased hydrophobicity of the NRHMS composites, explained by the acid-catalyzed bridging of free silanol groups to siloxane bonds, which was supported by the X-ray photoelectron spectroscopy analysis. Scanning transmission electron microscopy with energy dispersive X-ray spectroscopy elemental mapping revealed a good dispersion of the NR phase within the mesostructured silica. However, a high amount of added H2SO4 solution led to silica–NR phase separation due to the decreased hydrophobic interaction between the silica precursor and rubber chain, as well as an agglomeration of the NR phase itself. The mechanism of NRHMS nanocomposite formation under pH-controlled conditions was proposed to proceed via a cooperative self-assembly route.

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The Effect of Concentration, Solvent, and Temperature on Aggregation of a Commercial Calcium Sulfonate Additive as Studied by FTIR and Light Scattering Techniques

Cited by 10 publications

References 24 publications

Cross-Sectional Imaging of Boundary Lubrication Layer Formed by Fatty Acid by Means of Frequency-Modulation Atomic Force Microscopy

Cross-Sectional Imaging of Boundary Lubrication Layer Formed by Fatty Acid by Means of Frequency-Modulation Atomic Force Microscopy

Shear property of oil film containing oiliness additive in narrow gap measured with newly‐developed parallel‐disk viscometer supported by aerostatic bearing

Facile fabrication of mesostructured natural rubber/silica nanocomposites with enhanced thermal stability and hydrophobicity

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