Thermal-oxidation mechanism of dioctyl adipate base oil

Qian, Xuzheng; Xiang, Yaling; Shang, Hongfei; Cheng, Bingxue; Zhan, Shengpeng; Li, Jian

doi:10.1007/s40544-015-0099-x

Cited by 31 publications

(26 citation statements)

References 32 publications

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“…C 10 -C 18 compounds were detected in S 250 -S 300 , and the RC of BHT derivative 2-(tert-butyl)-4-methylphenol increased from 0.009% in S 230 to 0.646% in S 300 . Therefore, the KV of the aged oils was also significantly reduced [2,13]. Hydrogen atoms were quickly abstracted by the free radicals of the lubricating oils to improve the thermal oxidation stability.…”

Section: Molecular Structure: Changes With Temperaturementioning

confidence: 99%

Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

et al. 2020

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Synthetic hydrocarbon aviation lubricating oils (SHALOs) gradually degrade over time when subjected to high temperatures, resulting in their composition and properties varying over the operation lifetime. Therefore, understanding the SHALO degradation properties by elucidating the mechanism on a molecular level, as a function of high temperature, is of interest. A SHALO was subjected to thermal treatment (TT) at 180, 200, 230, 250, 270, or 300 °C for 2 h. The chemical compositions of six TT samples and one fresh oil were analyzed by fourier transform infrared F spectroscopy, advanced polymer chromatography, and gas chromatography/mass spectrometry. Furthermore, the physicochemical properties, such as kinematic viscosity, pour point, and acid number, of seven samples were determined. The oil samples were grouped by cluster analysis (CA) using a statistical method. The SHALO was identified to comprise 20 functional groups, including comb-like alkanes, long-chain diesters, amines, phenols, and other compounds. TT at <230 °C caused partial cracking of the SHALO base oils, with a concomitant change in the antioxidant content and type, and the polycondensation reactions were dominant. The observed antioxidant changes were not obvious from TT at >230 °C. A large number of small-molecule compounds were detected, including n-alkanes and olefins. TT at 250 °C was shown to be an important threshold for the kinematic viscosity, pour point, and acid number of the samples. Below 250 °C, the sample properties were relatively stable; but at elevated TT temperatures (>250 °C), the properties were observed to dramatically degrade. As the sample color was highly sensitive to temperature, the TT temperature induced rapid and significant color changes. The CA analysis results for the oil compounds at the molecular level were in good agreement with observed changes in the physicochemical properties at the macro level.

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Section: Molecular Structure: Changes With Temperaturementioning

confidence: 99%

Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

et al. 2020

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“…21,22 The ReaxFF force field, developed by the integration of quantum calculations and experimental study, 23,24 is frequently used in molecular dynamics simulations to provide an in-depth understanding of the process and mechanism of chemical reactions of multiatomic systems. 14,25,26 The reliability of ReaxFF has been demonstrated in many published reports. 27,28 In this study, comparative experimental analysis of the oxidation behavior of DOA and TDTM base oils was performed using pressure differential scanning calorimetry (PDSC) tests and oven accelerated oxidation tests.…”

Section: Introductionmentioning

confidence: 97%

“…Subsequently, a dynamic simulation is performed to calculate the molecular motion using the appropriate classical equation, eventually obtaining a series of important data such as the atomic configuration and fundamental physical properties . The ReaxFF force field, developed by the integration of quantum calculations and experimental study, is frequently used in molecular dynamics simulations to provide an in‐depth understanding of the process and mechanism of chemical reactions of multiatomic systems . The reliability of ReaxFF has been demonstrated in many published reports …”

Section: Introductionmentioning

confidence: 99%

“…6,7 Many studies have investigated the oxidation of hydrocarbon oils, and the free-radical chain oxidation mechanism has been proposed. [8][9][10][11][12] However, the oxidation process of ester linkages is different to that of hydrocarbons due to their unique characteristics, [13][14][15] and the oxidation mechanism of hydrocarbon oils does not satisfactorily explain the oxidation of synthetic ester oils. Several studies have reported structures of degradative products of diesters, whereas the structural details of polymerized products resulting from oxidation, as well as the polymerization mechanism, remain unclear.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the oxidation resistance of synthetic ester oils DOA and TDTM: Experimental evaluation and theoretical calculation

Jin

Duan

Wei

et al. 2019

Lubrication Science

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The oxidation behavior of the synthetic ester oils di‐isooctyl adipate (DOA) and tri‐isodecyl trimellitate (TDTM) was investigated by analysing the oxidation induction time and oxidation onset temperature via pressure differential scanning calorimetry tests, and the variation in viscosity after oven accelerated oxidation tests. Moreover, theoretical calculations of the fractional free volumes and oxygen diffusion coefficients of DOA and TDTM were performed, and atomistic‐scale insights into the oxidative mechanisms of both oils were proposed based on reactive molecular dynamic (RMD) simulations. Better oxidation resistance for TDTM was confirmed with experimental observations. RMD results indicated that the C―O bonds of the alcohol chain and ester group of DOA were susceptible to oxidation. However, only the dissociation of the C―O bond of the alcohol chain initiated the oxidation of TDTM. Additionally, more degradation fragments for DOA were identified, along with the formation of a polymerized product, while no large molecules formed for TDTM.

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“…In such machine systems, temperatures T higher than 1,000 °C can develop between the components. In these scenarios, traditional oil-based lubricant is not appropriate for use, because of its disadvantages such as unfavorable viscosity-temperature μ-T characteristics and flammability [3,4]. Thus, new lubricants suitable for such applications should be found and studied.…”

Section: Introductionmentioning

confidence: 99%

Thermocapillary migration mechanism of molten silicon droplets on horizontal solid surfaces

et al. 2017

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Abstract:Effective lubrication under extreme conditions such as high temperature is of considerable importance to ensure the reliability of a mechanical system. New lubricants that can endure high temperatures should be studied and employed as alternatives to traditional oil-based lubricant. In this paper, a thermocapillary model of a silicone-oil droplet is developed by solving the Navier-Stokes and energy equations to obtain the flow, pressure, and temperature fields. This is accomplished using a conservative microfluidic two-phase flow level set method designed to track the interface between two immiscible fluids. The numerical simulation accuracy is examined by comparing the numerical results with experimental results obtained for a silicone-oil droplet. Hence, the movement and deformation of molten silicon droplets on graphite and corundum are numerically simulated. The results show that a temperature gradient causes a tension gradient on the droplet surface, which in turn creates a thermocapillary vortex. As the vortex develops, the droplet migrates to the low-temperature zone. In the initial stage, the molten silicon droplet on the corundum substrate forms two opposite vortex cells, whereas two pairs of opposite vortices are formed in the silicone fluid on the graphite substrate. Multiple vortex cells gradually develop into a single vortex cell, and the migration velocity tends to be stable. The greater the basal temperature gradient, the stronger the internal thermocapillary convection of the molten silicon droplet has, which yields higher speeds.

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Thermal-oxidation mechanism of dioctyl adipate base oil

Cited by 31 publications

References 32 publications

Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

Comparison of the oxidation resistance of synthetic ester oils DOA and TDTM: Experimental evaluation and theoretical calculation

Thermocapillary migration mechanism of molten silicon droplets on horizontal solid surfaces

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