Viscosity Index Improvers Research Articles

Film Forming Capability of Polymer-Base Oil Lubricants in Elastohydrodynamic and Very Thin Film Regimes

The development of high-performance lubricants to insure the separation of mechanical parts, to reduce engine friction and consequently fuel consumption remains a major challenge for oil manufacturers. Polymer additives called viscosity index improvers (VII) have been extensively used to reduce the dependency of the lubricant’s viscosity on temperature, to maintain an acceptable hydrodynamic lubrication in extreme conditions. This work focuses on understanding the role of VII in engine lubricants to bridge their tribological response with their rheological behavior. Simplified lubricants are studied, composed of polymers of different chemistries, molecular weights and conformations added to a mineral base oil. Film thickness measurements are carried out in pure rolling and isothermal conditions to quantify and clarify the effect of polymer addition on the lubricants behavior in the elastohydrodynamic (EHD) and very thin film (VTF) regimes. They are compared with accurate analytical predictions based on rheological models which lead to a good agreement with measured film thicknesses in the EHD regime, whereas some polymer solutions present a significant deviation to EHD predictions at lower thickness, i.e. in the VTF regime. Several explanations are considered, among them the non-Newtonian behavior of the lubricants and the adsorption of some polymers on the surface of the solid bodies.

Probing the Interactions between Mimics of Pour Point Depressants (PPDs) and Viscosity Index Improvers (VIIs) in Engine Oil Using Fluorescently Labeled PPDs

The level of interpolymeric interactions experienced by a pyrene-labeled poly(octadecyl methacrylate) labeled with 6.7 mol % of 1-pyrenebutanol (Py(6.7)-PC18MA) was characterized by fluorescence in...

Epoxidized Oleic Acid‐Based Polymethacrylates as Viscosity Index Improvers

AbstractThis study reports two routes for the synthesis of epoxidized oleic acid (OLA)‐based polymethacrylates. The first one consisted of the synthesis followed by epoxidation of the OLA‐based methacrylate, 2‐(methacryloyloxy)ethyl oleate (MAEO), prior to its radical polymerization. In the second pathway, MAEO was first homopolymerized to afford poly(2‐(methacryloyloxy)ethyl oleate) (PMAEO) and, then, the internal double bonds of the oleate were epoxidized at different yields ranging from 20% to 100%. All polymeric structures were confirmed using 1H nuclear magnetic resonance (NMR), and characterized through size‐exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) analyses. The resulting polymers were then blended at 5 wt.% in a mineral paraffinic oil (MPO) and in a biobased organic triacylglycerol oil (OTO) to be evaluated as viscosity index improvers (VII). The partially epoxidized polymers up to 40% were soluble in MPO. According to a rheological study, the oil‐soluble epoxidized polymers resulting from the epoxidation of PMAEO exhibited a much higher influence on oil viscosities at high temperatures than at low temperatures compared to the low‐epoxidized PMAEO molecular weight obtained by the first strategy. Additionally, the viscosity indices of both lubricating oils were significantly improved with the addition of the epoxidized OLA‐based polymers resulting from the epoxidation of PMAEO, which confirmed their efficiency as VII.

Influence of Polyvinyl Palmitate Copolymer As Viscosity Index Improvers For Lube

Polyvinyl palmitates were synthesized by condensing Polyvinyl alcohol with palmitic acid in different ratios and characterized. Intrinsic viscosity and their Molecular weights were found using Mark-Houwnik equation. Viscosity index of diesel oil doped with the prepared polymers were determined and compared. From the results it was observed that there will be slight increase in the viscosity index of the diesel oil at different ratios of additives. From these results it was confirmed that these additives can be used as viscosity index improvers.

Synthesis of plant oil-based amide copolymethacrylates and their use as viscosity index improvers

Polymeric materials derived from fatty acids (FA)s were synthesized through free radical polymerization and evaluated as viscosity index improvers (VII) in an organic triglyceride lube oil (OTO). For this purpose, various FA-based copolymers were designed to own a reduced solubility at low temperature in OTO which can be gradually improved by increasing temperature. Different fatty amide methacrylates were chosen for their poorly oil-miscible repeating units while fatty ester methacrylates, 2-(methacryloyloxy)ethyl oleate (MAEO) and 2-(methacryloyloxy)ethyl 4-(dodecylthio)oleate (MAEOSC12), were used as oil-miscible comonomers for providing copolymers with a minimum of solubility in the lube oil. All copolymers were synthesized with a 50:50 M feed ratio and were fully characterized through 1H NMR, SEC, DSC, and TGA analyses. Then, rheological study of oil-copolymer blends revealed that copolymers containing –NH function were able to have a higher impact on oil viscosity at high than at low temperatures suggesting the coil copolymer expansion. This improvement of thickening power with temperature in OTO was further optimized by increasing the copolymer molecular weight, dispersity, concentration, pendant aliphatic chain length or by adding an additional aliphatic chain in the copolymer backbone. Moreover, copolymer additions in OTO did not disturb the initial Newtonian behavior of OTO at −30 °C which corresponds to the lube oil pour point.

Lipophilic polymethacrylate ionic liquids as lubricant additives

Despite the growing research field of polymeric ionic liquids used as materials for electrolytes and energy materials, catalysts, separation aides, and carbon materials, reports of lipophilic polymeric ionic liquids for lubricants are essentially nonexistent. Oil-miscible single molecule ionic liquids (ILs) are reported to perform well as neat lubricants and as additives in lubricating base oils. In this work, methacrylate type ionic liquid monomers containing ammonium or imidazolium cations and two different counter-anions were synthesized and used as co-monomers to obtain functional poly(alkyl methacrylates) (PAMAs) as viscosity index improvers (VII) additives for lubricants. The structure of the IL, including the cation, the anion, and the spacer’s length separating the IL from the methacrylate group, plays an important role in the resulting polymer solubility in PAO (poly-alpha olefin), solution rheology, friction, and wear behavior. Depending on the IL structure, VIIs containing up to 20% mol IL are soluble in PAO (grade 4), and demonstrate frictionandwear reduction, compared to a conventional oil-soluble PAMA. Notably, wear volume reduction of up to 80% compared to the oil-soluble control poly(dodecyl methacrylate) is observed.

Improving engine oil lubrication in light-duty vehicles by using of dispersing MWCNT and ZnO nanoparticles in 5W50 as viscosity index improvers (VII)

The objective of this study is to offer a suitable nano-lubricant (engine oils containing nanoparticles) to use in light-duty automotive industries in order to reach a higher ability and efficient oil in comparison to ordinary engine oils, in order to reduce cold start engine damages. Therefore, in present study a feasibility study of using a new nano-engine oil containing a combination of MWCNT (multi wall carbon nanotubes)-ZnO nanoparticles with the ratio of 30–70% has been arranged. Results of experimental study show a considerable decrease in viscosity of nano-engine oil (in comparison to viscosity of pure 5W50 oil) after adding 0.05% and 0.1% nanoparticles to 5W50. This viscosity reduction, reduces the damage caused by starting up the engine in cold start condition. In order to predict the viscosity of this applied nano-engine oil (obtained from experimental studies), the efficiency of using a mathematical correlation using response surface methods (RSM) was investigated for viscosity prediction. For the proposed correlation, R2 is equal to 0.9715 that shows its acceptable accuracy. An artificial neural network has also been used as the second method to predict viscosity in the range of 5 °C–55 °C and in solid volume fractions of 0.05%–1%. Selected structure of Artificial Neural Network with R = 9.999e−01 is the most optimal and precise structure among 100 studied structures.

(Invited) Polymer Simulations Under External Fields

In order to design next generation functional polymers, not only the structure but the dynamics under external field should be understood. In this paper we report our simulation approach to investigate the structure and dynamics. Polymer brush is used for the model system of very low friction such as synovial joints. Recently, polymer brush is focused as a functional binder of sodium ion secondary battery. Since sodium ions are hard to make passive film, or SEI (solid electrolyte interphase) layer on the negative electrode, functional polymer binder help to stabilize the atmosphere around the electrode. We simulate the ionic conductivity of polyelectrolyte binder system under external electric field. The conductivity depend on the polymer structure, such as hardness and linear charge density of the polymer chain. The other important function of polymers are the fluid dynamics effect of polymers under external fluid field. As a model system of VII (viscosity index improver) polymers, we simulate the dynamics under shear filed. The dynamics of polymers are studied for bulk system and the confined system. We made simulation algorithm. The Brownian motion of polymer segments are treated by Langevin Dynamics, and the solvent flow is treated by Lattice Boltzmann Method, in order to obtain both high computational efficiency and precise dynamics. We succeed to reproduce the flow dynamics of polymers under shear. Moreover, the model is extended to include long-range interactions of functional groups. In low dielectric constant medium such as lubricant oils, the functional groups interact as ionic groups in high dielectric constant medium such as waters. The specific results shows that the colloidal science in oils have many problems to be solved.

Role of dispersant on soot-induced wear in Cummins ISB engine test

Wear performance of two fully formulated engine oils was evaluated using the Cummins ISB engine test. One of the oil formulations used a multifunctional DVII (Dispersant Viscosity Index Improver) component with enhanced antiwear characteristics to improve durability of engine components while the other formulation comprised of a conventional additive package. After the completion of engine-dynamometer tests, valvetrain components operating primarily in boundary lubrication regime were inspected for wear and weight loss in order to understand soot induced wear effects. In addition, soot was extracted and characterized using temperature resolved XRD, TEM, XANES, BET, Raman and EDS. XRD phase analysis of residue left behind after soot oxidation showed presence of crystalline compounds embedded in the soot structure (CaSO4, Ca3(PO4)2, Zn3(PO4)2 and ZnO). These species form ash pre-cursors which get trapped in the DPF (Diesel Particulate Filter) placed in the engine exhaust stream. The turbostratic structure of both soot samples remains the same prior to oxidation; however, the embedded crystalline and amorphous species in the soot structure slightly change with oil formulation. Surface area of the soot measured using BET was found to be inversely proportional to the weight of residue. Additionally, used oil analysis was performed to understand variation in viscosity, wear elements and soot content before and after the test. Findings in this study provide deeper insights into the mechanism for improved wear protection provided by DVII.

Pour Point Depressants and Viscosity Index Improvers for Lubricating Oil: A Mini-Review

This work briefly describes the composition of the lubricating oiland the types of flow improvers, pointing out the advantages of nano-hybrid pour point depressant and some common types of nano-hybrid pour point depressant. The author summarizes the experimental instruments and methods which were commonly used in the study of the mechanism of pour point, pointing out the factors that affect its effect on the lubricating oil. The mechanism of the action of the pour point depressant and the viscosity index improvers in lubricating oil are described. The author describes the preparation, design and application of the environment-friendly pour point depressant, which helps researchers to study the lubricating oil pour point depressants. Keywords: Base lubricating oil, flow improvers, mechanism and method, environment-friendly, fuel combustion, pour point depressants.

Shear Dynamics of Viscosity Index Improver in Confined Geometry

Shear Dynamics of Viscosity Index Improver in Confined Geometry

Dodecylmethacrylate – olive oil copolymers as potential biodegradable pour point depressant for lubricating oil

ABSTRACTThe application of greener additives based on vegetable oils has attracted considerable interest due to their biocompatibility and enhanced additive performances compared to conventional additives. Keeping this view in mind and in continuation of our explorative studies on lube oil additives, copolymer of dodecylmethacrylate with olive oil have been synthesized in a focused mono-mode microwave oven using BZP (benzoyl peroxide) as radical initiator. Characterization of the prepared polymers has been performed by spectral (NMR, IR), and SEC-GPC analysis. Performance evaluation of the polymers as pour point depressant (PPD), and viscosity modifier (VM) / viscosity index improver (VII) in different base oils (mineral) have been performed by standard ASTM methods. Biodegradability of the prepared additives was tested against fungal pathogens and microorganisms by disc diffusion (DD) method and by soil burial test (SBT) method respectively. Thermal stability of each of them has been evaluated and included. The multifunctional performances have been compared and reported. The copolymers showed excellent PPD performance along with VM properties and potential biodegradability.

Polymers additive for improving the flow properties of lubricating oil

An investigation was conducted for the improvement of the physical properties of Lubricating oil. The copolymer used is ethylene propylene diene monomer (EPDM). The oil viscosity index (VI) and viscosity/temperature characteristics were improved at different concentrations 2468 and 10% by weight solutions. The efficiency of the additive as viscosity index and flow improvers was investigated. FT-IR analysis determines the change in the carbonyl group. Thermo gravimetric analysis (TGA), is used to study the degradation and thermal stability of the studied base stock samples.

Almond Oil as Potential Biodegradable Lube Oil Additive: A Green Alternative

Growing environmental concerns over the use of mineral oil based lubricants in various fields have led to an increased attention towards the use of environmentally benign bio-lubricants. Working in this direction, the present report describes the synthesis of a homopolymer of almond oil and its copolymers with decyl acrylate. The structures of the prepared polymers were confirmed using FT-IR, NMR, and GPC analysis. Additive performances of each of the prepared polymers as viscosity index improvers and pour point depressants were evaluated by standard ASTM methods. The thermal stability of each of the polymers was investigated. Biodegradability of all the polymers was also tested as per ISO 846:1997 against fungal pathogens. A comparison of their multifunctional performances was also studied and is reported. The copolymers showed better performances as viscosity index improvers and pour point depressants. The thermal stability of the copolymers was also found to be higher than the homopolymer. As expected, the homopolymer showed better biodegradability among the other polymers.

Chemically Modifying Vegetable Oils to Prepare Green Lubricants

Chemically modifying vegetable oils to produce an alternative to petroleum-based materials is one of the most important emerging industrial research areas today because of the adverse effects of petroleum products on the environment and the shortage of petroleum resources. Biolubricants, bioplasticizers, non-isocyanate polyurethanes, biofuel, coating materials, biocomposites, and other value-added chemicals can easily be produced by chemically modifying vegetable oils. This short review discusses using vegetable oils or their derivatives to prepare lubricants that are environmentally safe. Chemically modified vegetable oils are generally used as base fluids to formulate environmentally friendly lubricants. Reports of their application as sustainable additives have attracted special attention recently because of their enhanced multifunctional performances (single additives perform several functions, i.e., viscosity index improver, pour point depressant, antiwear products) and biodegradability compared with commercial additives. Here, we have reviewed the use of chemically modified vegetable oils as base fluids and additives to prepare a cost-effective and environmentally friendly lubricant composition.

Castor Oil Based Multifunctional Greener Additives for Lubricating Oil

Objective: The article investigates the performance of homopolymer of castor oil and its four copolymers with methyl methacrylate (MMA), dodecyl acrylate (DDA), 1- decene (1-D) and styrene (ST) as biodegradable multifunctional additive in the formulation of eco-friendly lubricant. Method: Homopolymer of castor oil (CO) and its copolymers with 10% (w/w) of each of the comonomers were synthesized using azobisisobutyronitrile (AIBN) as initiator. The polymers were characterized by spectral techniques (FT-IR and NMR spectroscopy). The molecular weight of all the prepared polymers was determined by Gel Permeation Chromatography (GPC). Result: The thermal stability of the polymers was determined by thermo gravimetric analysis (TGA). Performance evaluation of all the prepared polymers in two different of mineral base oils as viscosity index improver (VII), pour point depressant (PPD) and antiwear was carried out according to standard ASTM methods. Biodegradability of all the samples was tested through soil burial test (SBT) method. Keywords: Castor oil, homopolymer, copolymer, viscosity index improver, pour point depressant, antiwear, biodegradability.

Correlating Molecular Structure to the Behavior of Linear Styrene–Butadiene Viscosity Modifiers

The effect of linear styrene–butadiene polymer structure on the temperature–viscosity behavior of model polymer-base oil solutions is investigated using molecular dynamics simulations. Simulations of alternating, random, and block styrene–butadiene polymers in a dodecane solvent are used to calculate viscosity at 40 and 100 °C, reference temperatures for characterizing their function as viscosity modifiers. Mechanisms underlying this function are explored by quantifying the radius of gyration and intramolecular interactions of the polymers at the same reference temperatures. The block styrene–butadiene configuration exhibits the least change in viscosity with temperature, characteristic of a good viscosity modifier or viscosity index improver, and the behavior is correlated to the ability of this structure to form smaller coils with more intramolecular interactions at lower temperatures and then expand as temperature is increased. The results indicate that there is a correlation between styrene–butadiene polymer structure, additive function, and the mechanisms underlying that function.

Rheological Considerations on Polymer-Based Engine Lubricants: Viscosity Index Improvers versus Thickeners—Generalized Newtonian Models

ABSTRACTThe development of high-performance lubricants to decrease engine friction and then reduce fuel consumption remains a major challenge for oil manufacturers. Viscosity index improvers (VIIs) are additives used for decades to reduce the dependency of the lubricant's viscosity on temperature to maintain an acceptable lubrication in harsh conditions. Distinction between VIIs and thickeners in realistic engine conditions is of primary interest for oil manufacturers in order to optimize the formulation process. In this context, rheological studies can provide clear insights into the actual effect of such polymeric additives. The behavior of a simplified automotive lubricant is investigated at different temperatures and high pressure and high shear stress and modeling of the properties is proposed. Various polymers of different molecular weights and conformations were mixed in a hydrocracked mineral base oil. The viscosity variations with temperature, pressure, and shear stress, obtained from specific rheometers, were then represented by different models, namely, a Vogel-Fulcher-Tamman expression, a modified Williams-Landel-Ferry correlation, and a Carreau-Yasuda equation. Different rheological responses were observed and allowed the distinction between VIIs and thickeners under different temperature and pressure conditions. The hydrodynamic radii analysis provided an explanation of the rheological responses but also highlighted the limits of the Carreau-Yasuda equation when applied to VIIs. Therefore, the Zhang expression, based on the Maxwell model and applied here to low viscoelastic solutions, is proposed as an appropriate alternative.

Viscosity Index Improver for Engine Oils: An Experimental Study

Engine oils are widely used for lubrication purposes in automobile and related industries. Viscosity Index (VI) improver has found its largest commercial applications as additives to engine oils. Examples are power steering fluid, aircraft piston engine oils, modern internal-combustion engines, turbine engine oils (stationary and aircraft), and industrial gear oils. Viscosity Index improvers are added in the lube oils to reach the desired Viscosity Index (VI). The enhancement of VI of lube oils (Servoneum 100, Servopress 68, Servomesh SP 220, and Servocut 335) by the addition of viscosity index improvers (Methylmethacrylate (MMA), Polybutadiene rubber (PBR), and Polyisoprene-cis) has been studied. VI of blended oils, made from the lube oils (Servoneum 100, Servopress 68, Servomesh SP 220, and Servocut 335) by the addition of MMA, PBR, and Polyisoprene-cis, has shown the potential to reach the maximum value. It has been found that the occurrence of maximum VI depends on the lube oil used and the type and concentration of viscosity index improver.

Castor oil as potential multifunctional additive in the formulation of eco-friendly lubricant

The article investigates the performance of polymers prepared from castor oil and dodecyl acrylate as biodegradable multifunctional additive in the formulation of eco-friendly lubricant. Homopolymer of castor oil and its copolymers with dodecyl acrylate (DA) at different percentage ratios (w/w) were synthesized using azobisisobutyronitrile (AIBN) as initiator without any solvent. The polymers were characterized by spectral techniques (FT-IR and NMR spectroscopy). The molecular weight of all the prepared polymers was determined by gel permeation chromatography (GPC). The thermal stability of the polymers was determined by thermogravimetric analysis (TGA). Performance evaluation of all the prepared polymers in SN150 mineral oil as viscosity index improver (VII), pour point depressant (PPD) and antiwear were carried out according to standard ASTM methods. The action mechanism of the additives as PPD was studied by photo micrographic image. Biodegradability of all the samples was tested through soil burial test (SBT).