Ester-based Oils Research Articles

Synthesis and antioxidant properties of a novel arylamine antioxidant

AbstractA novel oil‐soluble arylamine antioxidant N1,N2‐diphenylethane‐1,2‐diamine (ND) was successfully synthesized, and the potential antioxidant behavior of which had never been reported before. The structure of ND was characterized via nuclear magnetic resonance (1H NMR, 13C NMR) and electron ionization mass spectrometry. The antioxidant performance of ND and its synergistic effect with 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT) in di‐2‐ethylhexyl sebacate were evaluated by pressurized differential scanning calorimetry, thermogravimetry analysis, and hot oil oxidation test. All the results indicated that the synthesized antioxidant ND exhibited outstanding antioxidant performance and showed prominent synergistic effect with BHT in ester base oil. Furthermore, the probable synergistic anti‐oxidative effect between ND and BHT was discussed, which was mainly induced by the formation of a fresh BHT radical and the regeneration of ND antioxidant.

Tribological synergies among chemical-modified graphene oxide nanomaterials and a phosphonium ionic liquid as additives of a biolubricant

In the present work, antifriction and antiwear synergies of two functionalized graphene oxides (reduced graphene oxide, rGO, and reduced graphene oxide modified with octadecylamine, rGO@ODA) with a phosphonium ionic liquid (IL) as additives of a biodegradable ester base oil, BIOE, were investigated. For this aim, four BIOE nanodispersions were formulated: two nanodispersions without IL and two others with IL (hybrid nanolubricants), being the nanodispersions: BIOE + 0.05 wt% rGO, BIOE + 0.05 wt% rGO@ODA, BIOE + 1 wt% IL + 0.05 wt% rGO and BIOE + 1 wt% IL + 0.05 wt% rGO@ODA, and all of them showing good temporal stability (at least 3 weeks), especially those containing the ionic liquid. Tribological tests, under pure sliding conditions, were made with the aforementioned nanolubricants and with neat BIOE under a 20 N working load. All hybrid and non-hybrid nanolubricants resulted in lower friction coefficients compared to BIOE oil, with the largest friction reduction of 34% achieved by the 1 wt% IL + 0.05 wt% rGO nanolubricant. Discs lubricated with the prepared nanolubricants showed less wear than discs lubricated with BIOE, achieving the highest reduction (34%) in wear track width also for the 1 wt% IL + 0.05 wt% rGO nanolubricant. In addition, through confocal Raman microscopy, as well as roughness analysis of tested discs, it can be concluded that surface repairing, synergistic effect and tribofilm formation mechanisms occur.

Tribological properties of hexagonal boron nitride nanoparticles or graphene nanoplatelets blended with an ionic liquid as additives of an ester base oil

AbstractAntifriction synergies between an ionic liquid (IL) and nanopowders as additives of an ester base oil were analysed at rolling conditions. For this aim, two nanodispersions based on hybrid combinations of hexagonal boron nitride nanoparticles (h‐BN) or graphene nanoplatelets (GnP) with tri(butyl) ethylphosphonium diethylphosphate ionic liquid as additives in triisotridecyltrimellitate (TTM) base oil and the mixture of TTM and IL were analysed using two tribometer techniques. Film thickness characterisation and tribological tests were performed at rolling conditions [5% slide‐roll‐ratio (SRR)], under 50N and at operating temperatures of 30, 50 and 80°C. Stribeck curves showed that friction coefficients for the prepared lubricants are lower than those found for the TTM, being the best friction behaviour for the hybrid GnP nanolubricant. Furthermore, friction torque loss tests were performed in rolling ball bearings, observing that for the two hybrid nanolubricants lower friction torque values were obtained.

Measurement of Tan-delta and DC Resistivity of Synthetic Ester Based Oil Filled with Fe2O3, TiO2 and Al2O3 Nanoparticles

ABSTRACT The dielectric properties of insulating liquids are very important for their application as insulation and coolant in electrical devices like transformers. It is important to monitor the health condition of transformers for uninterrupted and economical power supply. For this purpose, the simple insulating materials like pressboard and mineral oils are used. This paper presents an eco-friendly alternative to mineral oil in the form of the synthetic ester oil-based nanofluids. This paper aims to present the effect of nanoparticles on the dielectric dissipation factor and electrical resistivity of ester-based oil. In this paper, we are testing synthetic ester oils for DC resistivity and dielectric dissipation factor (Tan-delta) at different temperatures starting from room temperature up to 80°C by incorporating nanoparticles with 0.02 weight% concentration. Nanoparticles used in this study are Fe2O3, TiO2 and Al2O3. Synthetic ester oil is used as the base oil for testing. These oils are manufactured from raw materials that are basically formed by combining acids and alcohols. The heating chamber is used to heat the oil for different temperatures. Insulation resistance (IR) tester and oil dissipation factor meter are used to determine DC resistivity and dielectric dissipation factor (DDF) of simple synthetic ester oil and nano oil respectively. This paper presents the effect of nanoparticles and temperature on dielectric properties of synthetic ester-based oils.

Investigation of Aviation Lubricant Aging under Engine Representative Conditions

Measurement of the antioxidant additives during lubricant thermal degradation is a useful method for providing a quantitative basis to understand the performance of the lubricant. In this study, a synthetic ester-based aviation oil was thermally exposed for a period of 500 h under gas turbine aero engine representative conditions using a lubricant/system interaction simulator (L/SIS) test rig. Physical and chemical changes including kinematic viscosity, total acid number (TAN), and oil chemical composition were monitored during the experiment. The change in oil chemical composition, with a particular focus on antioxidant additives, was examined using gas chromatography–mass spectroscopy (GC-MS) techniques. The results indicate that the identified antioxidants in the lubricant, dioctyl diphenylamine (DODPA) and phenyl-α-naphthylamine (α-NPA), were consumed during the degradation process of the oil, with DODPA having a slightly higher depletion rate. Posttest analysis of the stressed samples showed an increase in viscosity and TAN of the lubricant oil in the course of the thermal exposure. Furthermore, the reaction of DODPA and α-NPA in an oil thermally degrading environment was compared using density functional theory (DFT). The calculations indicate a lower energy barrier for the reaction of oil with DODPA.

Experimental investigation for the solubilities of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) in polyol ester, polyvinylether, and polyalkylene glycol base oils

• Dimensional synthesis compared four-, six- and eight-bar mechanism gait trainers. • Eight-bar configuration had greater kinematic accuracy with constant input velocity. • Kinematic accuracy was similar for all mechanisms with well-controlled input. Knowledge of the solubility of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) in lubricant oil is an indispensable factor for designing refrigeration system and choosing suitable lubricant oil. In this work, the solubilities of R1234yf in polyol ester (POE) base oil, polyvinylether (PVE) base oil, and polyalkylene glycol (PAG) base oil were measured in the temperatures range from 273 K to 353 K based on the isochoric method. The experimental solubility data were correlated using the Peng-Robinson (PR) equation of state and Wilson activity coefficient model. The absolute average relative deviations of the experimental data and calculated values for the R1234yf + POE base oil system, R1234yf + PVE base oil system, and the R1234yf + PAG base oil system are 2.47%, 1.66%, and 1.29%, respectively.

Silica-Supported Fe(II), Co(II) and Ni(II) Complexes as Efficient Catalysts to Esterification of Levulinic acid with Polyol

Biomass-derived feedstocks were used to synthesize a new polyol-based ester for biolubricant production to overcome the dependence on mineral oil. Although biomass-derived oil is a potential alternative to polyol ester, upgrading is inevitable before using it as a biolubricant. Levulinic acid (model acid), obtained from a bio oil, was used for the esterification of two polyols, for example, neopentyl glycol (NPG) and trimethylolpropane (TMP), in the presence of ligand metal Fe(II), Co(II), and Ni(II) complexes as catalyst. Silica-supported Fe(II), Co(II) and Ni(II) complexes viz. [Fe(Tyr)(Amp)]Cl·SiO2, [Co(Phe)(Bpy)]Cl·SiO2 and [Ni(Leu)(Phen)]Cl·SiO2 were synthesized by the reaction of ligands [L-phenylalanine (Phe), L-tyrosine (Tyr), L-leucine (Leu), 4,4′-bipyridine (Bpy), 2-aminopyridine (Amp) and 1,10-phenanthroline (Phen)] with respective metal(II) chloride salts. All the metal complexes were characterized by elemental analysis, magnetic susceptibility, TGA/DTA, FTIR, powder-XRD and SEM methods. The catalytic activities of the complexes were further investigated via esterification of two polyols (e.g. neopentyl glycol and trimethylolpropane) by biomass-derived levulinic acid (LA). Herein, iron(II) complex was found to be more active, demonstrating its better efficiency as a catalyst towards the esterification of levulinic acid for synthesizing ester-based oils.

Ultralow Friction of a Tetrahedral Amorphous Carbon Film Lubricated with an Environmentally Friendly Ester-Based Oil

Ultralow Friction of a Tetrahedral Amorphous Carbon Film Lubricated with an Environmentally Friendly Ester-Based Oil

Green synthesis of ester base oil with high viscosity — Part II: Reaction kinetics study

As an eco-friendly lubricant base oil, ester base oil is receiving increasing attention. However, studies on synthetic reaction kinetics of high viscosity complex ester have been rarely reported. In this work, based on the principle of equal reactivity of all functional groups and simplified kinetics models, synthetic reaction kinetics for high viscosity complex ester was investigated in two steps. As for the esterification of trimethylolpropane with glutaric acid, the activation energies of the first and second stage were 55.3 and 73.5 kJ/mol, respectively. As for the esterification of the first step products with 2-ethylhexanoic acid, the activation energies of the first and second stage were 60.6 and 98.2 kJ/mol, respectively. As for the esterification of the first step products with n-heptanoic acid, its activation energy was 68.9 kJ/mol. A mutation phenomenon on reaction order from zero to second order was discovered, which could be explained by the strong adsorption of organic acid on catalyst surface. The conversion rate of carboxyl of synthetic reaction for mixed acid ester was estimated by simulation, and average relative error was less than 3.0%. The synthetic process of high viscosity complex ester was considered to consist of a series of parallel–consecutive reactions with addition–elimination mechanism.

Dependence of Tribological Performance and Tribopolymerization on the Surface Binding Strength of Selected Cycloalkane-Carboxylic Acid Additives

We recently reported the use of cyclopropanecarboxylic acid (CPCa) as a model additive that can readily react under the combined effect of flash heating and stress in steel tribocontacts to form tribopolymers, along with marked improvement in tribological performance. In this paper, we present results of how chemical structural modification of CPCa may impact on the formation of tribopolymers and hence friction and wear properties, both by experiments and molecular dynamics simulation. Four lubricant additives, viz., CPCa, cyclobutanecarboxylic acid (CBCa), cyclopropane-1,1-dicarboxylic acid (CPDCa), and cyclobutane-1,1-dicarboxylic acid (CBDCa) consisting of a metastable ring structure and one or two carboxyl groups dissolved in an ester base oil were studied. Friction and wear rate using these additives rank in the order of CPDCa < CBDCa < CPCa < CBCa. Raman spectroscopy analysis reveals that these additive molecules form tribopolymer films at the contact area. Molecular dynamics simulation shows that CPCa with the less stable cyclopropane ring fragments more readily than CBCa. Such fragmentation appears to be essential for subsequent tribopolymerization and formation of protective tribofilms. These simulations further demonstrate that having two carboxyl groups as in the case of CPDCa results in stronger binding of the additive molecules to the surface, thus increasing the residence time and hence facilitating mechanically or thermally induced dissociation and subsequent polymerization. The net result is that CPDCa gives the lowest friction and negligible wear under our testing conditions.

The thermal oxidation mechanism of TMPTO with antioxidants investigated by ReaxFF MD

PurposeThis paper aims to study the thermal oxidation performance of antioxidant additives in ester base oils deeply.Design/methodology/approachReaxFF molecular dynamics was used to simulate the thermal oxidation process of butyl octyl diphenylamine and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate as two antioxidant additives act on the Trimethylolpropane trioleate (TMPTO) base oil. Meanwhile, combining with the infrared spectroscopy characterization results of the thermal oxidation test, this paper provides theoretical support for the development of high-performance synthetic lubricants and their antioxidant additives.FindingsThe results show that butyl octyldiphenylamine easily removes the hydrogen atom on the secondary amine, which promotes the formation of more long carbon chain diene radicals or polyene hydroperoxides from TMPTO. Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate could easily decompose into octadecyl hydroperoxide and 2,6-di-tert-butyl 4-propionylphenol, which could convert into 2-tert-butyl-4-peroxyethyl-6-hydroperoxy-tert-butylphenol in the middle of the thermal oxidation reaction, prompting TMPTO to form more short-chain alkenyl and olefin hydroperoxide or other oxide.Originality/valueThe main change characteristics of base oil molecules are the first thermal decomposition to form oleic acid groups and ethane cyclopropane methyl oleate. Under the action of butyl octyldiphenylamine and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate, the deep oxidation and decomposition reaction are slowed down.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0037/

Investigation of the stability in Pickering emulsions preparation with commercial cosmetic ingredients

In recent years, the use of Pickering emulsions in topical formulation has received growing interest from academics to cosmetic and pharmaceutical industries. Compared to regular emulsions stabilized with synthetic low molecular weight surfactants, Pickering emulsions avoid the use of hazardous surfactants and show improved stability, making them as new targeting systems in cosmetic and pharmaceutical products. However, most of the studies on Pickering emulsions were performed with non-biocompatible model oils such as toluene, n-dodecane or hexadecane. For a cosmetic or pharmaceutical application, the change for a biocompatible oil is necessary, but this often induces dramatic changes or modifications in the emulsion stability. Therefore, in this work, we try to fill the gap by applying the discovered rules drew from previous reported model studies to the Pickering systems of industrial cosmetic ingredients. In particular, we investigate the stability in Pickering emulsions produced from biocompatible oils including, silicone and ester-based oils that are commonly used in personal care products. Our result shows that the resultant emulsions preparation with biocompatible oils and stabilized with commercial fumed silica particles follow a rule that derived from our model study. Wettability of particles are discussed to predict the emulsion type and their stability during storage. The findings in this study will provide a practical guide to researchers to better understand the emulsion properties produced from commercial cosmetic ingredients and advance their possible industrial applications.

Kinetic analysis of urethane formation between castor oil-based ester polyol and 4,4’-diphenyl methane diisocyanate

ABSTRACT Kinetics of urethane formation between castor oil-based ester polyol (COEP) and 4,4′diphenyl methane diisocyanate (MDI) was evaluated using Differential Scanning Calorimeter (DSC) technique. The autocatalytic effect of urethane groups during polyurethane formation was confirmed through this study. DSC runs were made under dynamic heating schedule at various heating rates, viz.: 5, 10, 15 and 20 K/min. Single Heating rates like Chatterjee–Conrad and multiple heating rate method like Ozawa models were used to evaluate the kinetic parameter. Isocyanate index (Eq. of NCO/Eq. of OH) of 1 was used for the reaction between COEP and MDI. DSC thermograms exhibit two isotherms at 70°C and 120°C. Kinetic parameters adopting different models, in terms of activation energy, suggest that the urethane formation occurs grossly in two stages: the first step being standard uncatalysed urethane reaction and the following second step presumably autocatalysed urethane formation. The two exotherms were resolved into two portions. Kinetic analysis was undertaken for the unresolved DSC as well as the resolved ones, treating the resolved thermograms as the outcome of two independent competing reactions.

Preparation and tribological properties of calcium perrhenate as high-performance lubricating additive toward a broad temperature range

In this article, nano-sized calcium perrhenate was prepared using the microemulsion reaction method. By the aid of surfactant, the calcium perrhenate was suspended in pentaerythritol ester base oil to serve as a lubricating additive. The tribological performances of the oil containing calcium perrhenate at elevated temperatures were investigated by four-ball tests and ball-on-disk reciprocating sliding tests. The underlying lubricating mechanism of the calcium perrhenate additive was explored using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry/thermogravimetry, Raman spectroscopy, and X-ray photoelectron spectroscopy. The four-ball test results indicated that the oil containing calcium perrhenate featured lower friction coefficients, smaller wear scar diameters, and lower temperature rising performance than the base oil under an applied load of 392N. The optimum lubricating property was obtained when the additive was at a concentration of 0.05wt%. The tribological performance in a wide temperature range results showed that the friction coefficients of the oil containing calcium perrhenate were slightly lower than those of the base oil at a relatively low temperature range, and decreased as the temperature increased within a high range. The improved tribological performances owed to the formation of a protective layer, which consisted of the shear-susceptible calcium perrhenate additive as well as some native metal oxides that enhanced the layer carrying capacity during rubbing after chemical degradation of base oil. This protective layer acted as a barrier between the rubbing surfaces, preventing them from directly contacting each other at elevated temperatures.

Green synthesis of ester base oil with high viscosity – Part Ⅰ: Catalyst preparation, characterization, evaluation, and mechanism analysis

High viscosity ester base oil, as an eco-friendly lubricant base oil with high performance, can significantly reduce the friction, wear, and energy consumption of large machinery. However, there is less research on the preparation of heterogeneous catalysts for synthesis of high viscosity ester oil. In this work, Sn/Zr mixed oxide catalysts were prepared for the green synthesis of ester base oil with high viscosity. This approach gets rid of additional template, surfactant, organic solvent, sulfur, nitrogen, phosphorus, and halogen, thereby avoiding the potential environmental pollution. A superior powdered catalyst MO-Sn8Zr-9.0-160-18 was developed with optimized Sn/Zr molar ratio, pH, hydrothermal temperature, and hydrothermal time of 8:1, 9.0, 160 °C, and 18 h, respectively. Results of catalyst characterization indicated that the developed catalysts were mesoporous materials with hydrophobic properties, allowing for free diffusion of macromolecules, adsorption of reactants, and desorption of water. Additionally, the specific surface area, pore volume, pore diameter, and surface hydrophobicity of catalyst were enhanced by doping Zr, so the catalysts with higher [Sn/Zr]ICP/[Sn/Zr]XPS exhibited better catalytic activity. Preformed catalyst was prepared by simple mechanical mixing method to achieve better catalyst separation. The specific surface area, acid amount, and acid strength of catalyst were indeed improved significantly after catalyst molding. By programmed heating, the preformed catalyst achieved a maximum carboxyl conversion of 97.2%. Moreover, spent catalyst could be reactivated via solvent washing, drying, calcination, and hydrogen reduction, exhibiting good reusability.

Two fatty acid anion-based ionic liquids - part II: Effectiveness as an additive to a polyol ester

This work is about the use of two ionic liquids obtained from fatty acids (FAILs) as an additive at 0.5 and 2 wt% to a polyol ester (POE) base oil. Tribological tests under two different configurations (reciprocating and sliding/rolling “ball-on-disc”) were performed at different temperatures and loads. Worn surface was measured and analyzed after reciprocating experiments by confocal and scanning electron microscopies and by X-ray photoelectron spectroscopy (XPS). Main results showed that these FAILs at low concentration did not change the viscosity of the POE and hence the tribological behaviors of the mixtures and the POE under elastohydrodynamic lubrication (EHL) in rolling/sliding tests were similar, but using mixtures resulted in lower friction regarding the POE under mixed lubrication regime; the friction behavior in reciprocating tests was similar with the use of all mixtures and the POE at 25 °C for the two loads used, while the mixtures outperformed the antiwear behavior of the POE; the antifriction behavior of the mixtures under both loads at 100 °C was slightly worse than that of the POE and all mixtures had better antiwear performance than the POE.

Analytical, numerical, and experimental investigation of the influence of lubrication on the drawing behavior of copper alloy

Environmentally friendly products are increasing demand and the challenge is to combine them with optimal efficiency in industrial processes. In cold drawing, lubrication improves the surface and dimensional quality of the workpiece, reduce tool wear, work loads, and maintenance intervention. Ester-based, vegetable-derived lubricants have interesting properties, such as biodegradability and low toxicity, but their application in forming processes has not yet been investigated despite their use in machining operations. In this work, we evaluated the drawing strength , surface roughness, and microhardness of electrolytic copper in the dry (non-lubricated) condition and using three different types of lubrication: powdered graphite, molybdenum sulfide grease, and ester-based oil, a possible environmentally friendly lubrication substitute for petroleum-derived lubricants. The drawing strength proved to be 23.4% lower when using grease and ester-based oil compared to the dry process, and the grease and ester-based oil presented the same result regarding process performance and material characteristics. Thus, combined with the fact that the ester-based oil led to the lowest friction coefficient between cooper and tool steel among the tested lubricants, it was possible to demonstrate that it can be used as an alternative to conventional products in cold- drawing operations of the tested cooper alloy.

Study on the Lubrication Performances of Rolling Oil for Cold Rolled Laminated Cu/Al Composite Sheet

Three kinds of ester base oils (D85, D100, D115), dodecyl alcohol, dodecyl acid, butyl stearate as oiliness agents, and thiophosphate, fatty alcohol phosphates and dibutyl phosphate as extreme pressure agents were used to prepare and investigate the tribological properties of rolling oils for cold rolled laminated Cu/Al composite sheet by an orthogonal experiment, and lubrication performances of the rolling oils were studied through rolling experiments. Surface roughness and the interface of Cu/Al composite sheet were analyzed. The results show that the optimum tribological properties of the rolling oil is compose of D100 as basic oil, butyl stearate as oiliness agent and the compound ratio of fatty alcohol phosphates and thiophosphate of 3:1 as extreme pressure antiwar agent. The PB value reaches 1020 N, the coefficient of friction is 0.0795. Basic oil is the main factor of rolling capacity. The rolling oil contented D115, showed the best rolling capacity while the minimum thickness was only 0.045mm. The addition of butyl stearate improved the surface quality of both copper and aluminum side of the rolled stripes and make the sheet surface roughness decreased. After cold rolling, new composite interface, which is clear and tightly bound replaced the brittle mesophase.

Preparation of complex polyol ester base oil for lubricant from cyclohexane oxidation waste water

Oxidation of cyclohexane in air produces cyclohexanone and cyclohexanol in cyclopol-bis process along with waste water stream containing valuable carboxylic acids. Process is devised in this manuscript to prepare complex polyol ester base oil by utilizing the waste water. The waste water stream from the cyclohexane oxidation process of Gujarat state fertilizers and chemicals ltd. has been vacuum distilled with a vacuum of 700 mmHg to remove water followed by filtration to separate the solid and liquid fractions. The liquid fraction is reacted with diethylene glycol to synthesize complex polyol ester base oil for lubricant. The base oil so obtained has a kinematic viscosity of 113 cSt at 40°C, pour point of -33°C and viscosity index of 109.

Tribological behavior of mineral and synthetic ester base oil containing MoS2 nanoparticles

0.2, 1.0, and 2.0 wt.% concentration of molybdenum disulfide (MoS2) nanoparticles were dispersed in mineral and synthetic ester base oil. Their tribological behavior investigated using a tribometer with pin-on-disk and four-ball configuration under different conditions of contact pressures, sliding speeds and oil bath temperatures, respectively. The results demonstrate that nano-MoS2 in mineral oil can reduce wear and friction coefficient characteristics at all concentrations tested, especially at 2.0 wt.%. XPS analysis of the worn surfaces indicated that decomposed MoS2 was adsorbed on worn surface, and S and Mo elements of the compound reacted with the metal and existed in the form of sulfide or molybdenum compounds, both of which contributed to the formation of a mix lubricating film. A wear mechanism of MoS2 as antiwear additive is proposed.