Succinimide Dispersants Research Articles

Process intensification for production of dispersants via integration of reaction and separation in a horizontal thin film evaporator

Process intensification can be achieved in specialty chemicals manufacturing via transition from batch-to-continuous processing. However, the absence of headspace in a continuous tubular reactor limits the ability to remove volatile byproducts from the reacting liquid flow. Previous studies showed that the production of succinimide dispersants follows a two-step amidation-dehydration pathway in which water is formed as a by-product. The inability to remove this water imposed a thermodynamic equilibrium limitation on the dehydration step, and hence necessitated a downstream drying step to obtain a dehydrated dispersant product within commercial specifications. In the present study, the use of an agitated, horizontal thin film evaporator (TFE) was investigated as a continuously operated reactive separator which combines reaction and dehydration into a single operating unit, reducing the overall cost and physical footprint of the process. The continuous TFE unit was first experimentally investigated as a stand-alone, integrated reactor-separator. Using this configuration, the obtained imide yield consistently exceeded the maximum thermodynamic yield at each operating temperature, confirming the efficiency of the integrated reaction and separation steps in the TFE. Next, the unit was modeled by integrating reaction kinetics with mass and energy balance equations, using appropriate correlations for heat and mass transfer from the literature which were verified for the experimental set-up. This model provided insights into the system behavior across different operating conditions, including the role of forward and reverse reactions along the TFE unit length. The model was then used to confirm the feasibility of replacing the two-step tubular reactor-evaporator process with a single TFE unit as an intensified reactive separator, further reducing the physical footprint of the process by enabling compact modular process designs.

Influence of a Succinimide Dispersant on the Tribological Performance of MoS2 Nanoparticles

Influence of a Succinimide Dispersant on the Tribological Performance of MoS2 Nanoparticles

Characterization of Base Oil and Additive Oxidation Products from Formulated Lubricant by Ultra-High Resolution Mass Spectrometry

Automotive formulated lubricants are high value products composed of 80% base oil and 20% various additives. During their life service, lubricants are exposed to several factors that will cause degradation over time, such as high temperature, shear, and oxidation. Base oil is a complex combination of hydrocarbons that are relatively sensitive to oxidation. During the initiation phase of oxidation, free radicals are formed, leading to the production of hydroperoxide ROOH and an alkyl radical R•. These compounds will react with the base oil molecules to form aldehydes, ketones, and carboxylic acids in the termination phase. Owing to the molecular complexity of these mixtures, Fourier transform mass spectrometry seems to be the most appropriate tool to cover their wide range of compounds due to its ultra-high resolving power and mass accuracy. In this study, a native formulated lubricant and its different oxidized states at 140 °C under air flow (3, 5, 7, 8, and 9 days of oxidation) were analyzed by FTICR MS. The combination of atmospheric pressure chemical ionization (APCI) was used to achieve a non-selective ionization of molecules, including base oils, while Electrospray ionization (ESI) was used to selectively ionize acidic molecules. Apparent Kendrick mass defect (aKMD) plots were used to separate homologous series of molecules on different horizontal lines on the basis of the CH2 repetition unit. Aging of lubricants was mainly characterized by a rapid consumption of certain additive families, such as molybdenum dithiocarbamates (MoDTCs) and zinc dithiophosphate (ZnDTPs), but also by the emergence of many oxidation products. Thus, the presence of aldehydes, ketones, and acids was characterized in the early stage of aging while larger products from polymerization were observed in a more advanced stage of aging. Interaction products between peroxy radicals and hindered phenols/alkyl diphenylamines (ADPAs) antioxidations were elucidated toward the high m/z. The formation of such products can be explained by trapping mechanisms of these additives at high temperature (>120 °C). Other types of interaction products were observed with the formation of antioxidant complexes. Additive degradation products were also characterized. For instance, polyisobutenyl succinimide dispersant oxidation products were clearly evidenced on the aKMD plots due to the gaps of 56 Da between each point. Overall, this study demonstrated the efficiency of the aKMD approach, and the use of ESI/APCI to characterize base oil and additive oxidation products.

Effect of Polyisobutylene Succinimide on the Physical Stability of an Environmentally Friendly Pesticide Oil Dispersion Suspension

Oil dispersible suspension concentrates are safe, green, and environmentally friendly formulations. Problems such as layering, pasting, and bottoming are frequently encountered during the production, storage, and transportation process. Polyisobutylene succinimide functions as a dispersant and exhibits great potential to improve the physical stability of the oil dispersible suspension concentrate. From a microscopic perspective, the sorption characteristics of the polyisobutylene succinimide dispersant T151 on penoxsulam particle surfaces were comprehensively evaluated with XPS, FTIR, and SEM. The T151 adsorption procedure complied with a pseudo-second-order kinetic adsorption model, and it was a kind of physical sorption with an Ea of 22.57 kJ⋅mol⁻¹. The T151 sorption model was consistent with the Langmuir isotherm. The adsorption process was spontaneous and followed by an entropy increase. The ΔH^θ of dispersant T151 on the surface of penoxsulam particles was 31.59 kJ⋅mol⁻¹. The adsorption procedure was endothermic, and the primary force was hydrogen bonding. The XPS results showed that the F and S electronic peaks at the penoxsulam interface decreased, and that the C electronic peak increased significantly after the adsorption of dispersant T151, indicating the adsorption on the surface of penoxsulam particles. The results of this study provide a vital theoretical basis for the application of polyisobutylene succinimide dispersants in oil dispersible suspension systems.

Batch-to-Continuous transition in the specialty chemicals Industry: Impact of operational differences on the production of dispersants

Specialty chemicals are typically produced in large-volume batch reactors characterized by straightforward operation but limited efficiency. Process intensification via transition from batch to continuous operation offers the prospect of strong improvements over current state-of-the-art in energy intensity, process safety, capital cost, and physical footprint. The present study investigated the production of two dispersants to demonstrate the viability of batch-to-continuous transition for the specialty chemicals industry: Succinate ester dispersants, formed in a one-step addition reaction, and succinimide dispersants, formed via a two-step reaction with water as by-product. While the ester process showed identical dispersant yields in batch and continuous operation under identical conditions, the succinimide process produced significantly higher yields in the batch compared to the continuous reactor. This could be traced back to an operational difference between these processes: In the batch process, the by-product water is continuously removed from the reactive mixture while purging the reactor head space, rendering the dehydration step effectively irreversible. In contrast, to prevent steam-induced foaming, the continuous reactor is operated at high-enough pressure to maintain water in the liquid phase. This renders the dehydration step incomplete due to thermodynamic equilibrium limitations. However, the full succinimide product yield could be recovered via subsequent continuous drying using a thin film evaporator. This product was indistinguishable from the batch product and fulfilled commercial specifications. Finally, full reversible reaction kinetics were derived based on the continuous reactor operation. Comparison between batch operation results and reactor modeling predictions indicated that the slow apparent kinetics of the industrial batch process is the result of mass transfer limitations due to slow water evaporation, and not caused by limitations in the intrinsic reaction kinetics.

Combination of nano-particles of graphite and PTFE in the right amount for synergism as anti-wear and extreme pressure additive in oil

Solid lubricants (SLs) are known to enhance the tribo-performance of oils significantly. Polytetrafluoroethylene (PTFE) particles have proved as an excellent extreme-pressure additive (EPA) but not as so good anti-wear additive (AWA). In contrast, the graphite nano-particles (NPs) are known as very good AWA but not so promising EPA. In this context, graphite and PTFE particles with different shapes (graphite-laminar and PTFE- spherical) and sizes (graphite- 60–120 nm and PTFE- 11–13 μm) were used in combination in different amounts for exploring possible synergism as AWA and EPA. A series of oils based on Group III (Gr III) with polyisobutylene succinimide (PIBSI) dispersant (1 wt%) along with an increasing amount of graphite NPs (0%–4%) and a simultaneous decrease in PTFE NPs (4%–0%) was prepared. The tribo-performance of oils was evaluated on Four ball tester for EP (weld-load) and anti-wear performance. Formulations were characterized for density, viscosity, and viscosity index. Also, the stability of oils was monitored through visual observation, and it was more than two months. Combo-oils showed improvement in anti-wear (AW) performance up to 54% for the concentration of 2 wt% each. For AW, synergism was observed, while for extreme pressure (EP) property, PTFE particles in isolation proved best, showing almost 350% improvement for group III oil. The inclusion of graphite particles step by step deteriorated the performance. The SEM (Scanning electron microscopy) and EDAX (Energy-dispersive X-ray) were used to analyze worn surfaces of ball and film formation mechanism.

Effect of Dispersant Concentration With Friction Modifiers and Anti-Wear Additives on the Tribofilm Composition and Boundary Friction

Abstract To extend drain intervals and improve efficiency, new engine oils with increased dispersant concentration and reduced viscosity are required. Low viscosity engine oils can increase the prevalence of boundary friction at low temperature and increase its severity at higher temperatures. As a result, combinations of organic and inorganic friction modifiers (FM) will be used to reduce boundary friction across a range of temperatures, also preventing damage to vehicle catalysts. This paper presents an experimental case study of such a new generation of fully formulated engine lubricants with varying concentrations of polyisobutylene succinimide dispersant, organic, and inorganic FM. Representative conditions pertaining to those encountered at the top dead center reversal of the piston compression ring-cylinder liner contact are created, and the generated friction measured through use of a sliding-strip tribometry. Subsequently, X-ray photoelectron spectroscopy (XPS) is used to determine the composition of the formed surface tribofilms in order to explain the observed frictional characteristics. The key interactions and frictional behavior of the dispersant and friction modifiers are highlighted across a range of operating temperatures.

Synthesis and characterization of modified polyisobutylene-based dispersants from polyisobutylene succinimides

In this study, Alkenyl succinimides with different alkyl chain lengths were synthesized using polyisobutylene (PIB) with the molecular weights of 1000 and 1300, which displayed the best functional properties. The secondary amines found in b-Polyisobutylene succinimide (b-PIBSI) dispersants were prepared by attaching PIB chains to a polyamine core via two succinimide moieties. In this work, detergent/dispersant type additives were synthesized based on polyisobutylene succinic anhydride (PIBSA) and its aminated compounds (PIBSI) with tetraethylenepentamine (TEPA). The resulting PIBSA and PIBSI characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and gel permeation chromatography (GPC) spectroscopies were greatly complicated because of the interactions between the carbonyls of the succinimide groups and unreacted secondary amines of the Mb-PIBSI dispersants. The viscoelasticity of obtained PIBSI indicated the increase in storage modulus with time which illustrated the increase in the solid-like properties of PIBSI. Therefore, an alternative procedure was developed based on fluorescence quenching of the succinimides by secondary amines and urethane groups.

Examination of lubricity properties of mineral base oil, containing nanoparticles of hexagonal boron nitride, and evaluation of the influence of surfactants on their sedimentation

The article presents the results of tests on the lubricity properties of SN150 base oil containing hexagonal boron nitride (h-BN) of different granulation. The boron nitride with a particle size below 100 nm and the second one with a particle size below 25 μm were used. The lubricity tests were carried out on a four-ball apparatus. The methodology of these tests was determined on the basis of the normative document PN-EN ISO 20623: 2018-02, which contains the following parameters characterising the lubricity: initial seizure load ISL [N], weld load WL [N], load-wear index LWI [N], mean wear scar diameter MWSD [mm] obtained in a long duration wear test under a specified load; wear-load curve, i.e., the dependence of the mean wear scar diameter on the load, was also performed. Tests were also carried out to check the influence of selected surfactants on the sedimentation process of hexagonal boron nitride in the SN150 mineral base oil. Based on the conducted research and their analysis, it was found that hexagonal boron nitride has a positive effect on the lubricating properties of the base oil; better results were obtained for the boron nano-nitride with a particle size below 100 nm. It was also found that the problem of sedimentation of the solid particles of hexagonal boron nitride was solved by the addition of succinimide dispersant. Keywords: tribology, lubricity, boron nitride, surfactants, sedimentation

Effects of Dispersant and ZDDP Additives on Fretting Wear

This paper examines the effect of dispersant and anti-wear additives on fretting wear in lubricated bearing steel contacts. Reciprocating sliding ball-on-flat fretting tests with a stroke length of 50 μm have been carried out on steel-to-steel contacts in both dry and lubricated conditions. Wear and friction coefficient have been measured, and surface characterisation has been carried out using optical techniques to investigate fretting wear. The presence of base oil reduces fretting wear markedly compared to dry conditions, but fretting damage is still observed at low reciprocation frequencies. As frequency is increased, there is a transition from oxidative to adhesive/scuffing damage. The anti-wear additive ZDDP is effective in forming a tribofilm on the surfaces and reducing visible oxidation and wear. A succinimide dispersant also reduces the accumulation of solid debris but does not alleviate wear damage. The combination of both ZDDP anti-wear additive and dispersant in base oil appears to provide significant protection against fretting wear.

Multifunctional lubricant additive derived from polyisobutylene succinimide dispersant

A new multifunctional lubricant additive (PIBSI-BSb) was synthesized by modifying polyisobutylene succinimide dispersant (PIBSI) with borated Schiff base. The results show that the antiwear and antioxidant properties of PIBSI were improved by modification with borated Schiff base, but the dispersibility was not decreased. Compared with PIBSI, the oxidation induction time (OIT) of PAO containing PIBSI-BSb was prolonged by 6.26 times, and the mean wear volume of steel ball lubricated by the PIBSI-BSb was reduced by 79.1%. The worn scars of steel balls were analyzed by SEM, EDS and XPS. The tribofilm consists of B2O3, FeO, N-containing organic compounds and iron fluoride, which indicates that the B and F atoms of PIBSI-BSb improve the antiwear capabilities.

The Autoxidation of Alkenyl Succinimides—Mimics for Polyisobutenyl Succinimide Dispersants

Short chain alkenyl succinimides (ASIs) were synthesized and used as high purity chemical models to investigate the autoxidative degradation at 170 °C of polyisobutenyl succinimide dispersants (PIBSIs), a significant additive in automotive engine lubricants. Degradation products were characterized by gas chromatography–electron ionization mass spectrometry and quantified by gas chromatography-flame ionization detection. The rate of autoxidation of ASIs in a model lubricant, squalane, was also investigated. Although this is a complex molecule containing many possible sites of radical attack, all of the autoxidation products identified result from attack at the double bond or the adjacent allylic hydrogen atoms, which indicates the controlling influence of the double bond in the degradation of alkenyl succinimides, and therefore of commercial polyisobutenyl succinimide dispersants. The observed site-selective cleavage of the ASI structure, and by analogy PIBSI dispersants, would yield products that both reduce dispersancy and promote the formation of insoluble products that could have a detrimental effect on lubricant performance.

A complex interdependence of dispersant in nano-suspensions with varying amount of graphite particles on its stability and tribological performance

Abstract In the present work, series of nano-oils with and without polyisobutylene succinimide (PIBSI- 1 wt%) dispersant was prepared with 55 nm graphite nano-particles (NPs) (1, 2, 3 and 4 wt%) to highlight the role of dispersant and concentration of NPs on controlling tribological performance and stability of nano-oils. It was concluded that dispersant proved beneficial for the stability of nano-oils (up to 50 days). NPs proved significantly effective to enhance the anti-wear (AW) performance by 60% and maximum improvement was recorded for 3 wt% NPs. Extreme-pressure (EP) performance was also enhanced by 80%. Atomic force microscopy (AFM) on worn ball surfaces showed lowest roughness and highest bearing area in case of most performing oil with dispersant and 3 wt% NPs.

Chemical Modification of Polyisobutylene Succinimide Dispersants and Characterization of Their Associative Properties.

The secondary amines found in b-PIBSI dispersants prepared by attaching two polyisobutylene chains to a polyamine core via two succinimide moieties were reacted with ethylene carbonate (EC). The reaction generated urethane bonds on the polyamine core to yield the modified b-PIBSI dispersants (Mb-PIBSI). Five dispersants were prepared by reacting 2 molar equivalent (meq) of polyisobutylene terminated at one end with a succinic anhydride moiety (PIBSA) with 1 meq of hexamethylenediamine (HMDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), and pentaethylenehexamine (PEHA) to yield the corresponding b-PIBSI dispersants. Characterization of the level of secondary amine modification for the Mb-PIBSI dispersants with traditional techniques such as FTIR and (1)H NMR spectroscopies was greatly complicated by interactions between the carbonyls of the succinimide groups and unreacted secondary amines of the Mb-PIBSI dispersants. Therefore, an alternative procedure was developed based on fluorescence quenching of the succinimides by secondary amines and urethane groups. The procedure took advantage of the fact that the succinimide fluorescence of the Mb-PIBSI dispersants was quenched much more efficiently by secondary amines than by the urethane groups that resulted from the EC modification of the amines. While EC modification did not proceed for b-PIBSI-DETA and b-PIBSI-TETA certainly due to steric hindrance, 60 and 70% of the secondary amines found in the longer polyamine core of b-PIBSI-TEPA and b-PIBSI-PEHA had reacted with EC as determined by the fluorescence quenching analysis. Furthermore, the ability of the Mb-PIBSI dispersants to adsorb at the surface of carbon black particles used as mimic of the carbonaceous particles typically found in engine oils was compared to that of their unmodified analogues.

Characterization of the Chemical Composition of Polyisobutylene-Based Oil-Soluble Dispersants by Fluorescence

A novel methodology based on fluorescence quenching measurements is introduced to determine quantitatively the amine content of polyisobutylene succinimide (PIBSI) dispersants used as engine oil-additives. To this end, a series of five PIBSI dispersants were prepared by reacting 2 mol equiv of polyisobutylene succinic anhydride (PIBSA) with 1 mol equiv of hexamethylenediamine (HMDA), diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine to yield the corresponding b-PIBSI dispersants. After having demonstrated that the presence of hydrogen bonds between the polyamine linker and the succinimide carbonyls of the dispersants prevents the quantitative analysis of the (1)H NMR and FTIR spectra of the dispersants to determine their chemical composition, alternative procedures based on gel permeation chromatography (GPC) and fluorescence quenching were implemented to estimate the amine content of the b-PIBSI dispersants. Taking advantage of the doubling in size that occurs when 2 mol of PIBSA are reacted with 1 mol of HMDA, a combination of GPC and FTIR was employed to follow how the chemical composition and molecular weight distribution of the polymers produced evolved with the reaction of PIBSA and HMDA mixed at different molar ratios. These experiments provided the PIBSA-to-HMDA molar ratio yielding the largest b-PIBSI dispersants and this molar ratio was then selected to prepare the four other dispersants. Having prepared five b-PIBSI dispersants with well-defined secondary amine content, the fluorescence of the succinimide groups was found to decrease with increasing number of secondary amines present in the polyamine linker. This result suggests that fluorescence quenching provides a valid method to determine the chemical composition of b-PIBSI dispersants which is otherwise difficult to characterize by standard (1)H NMR and FTIR spectroscopies.

The Antagonism between Succinimide Dispersants and a Secondary Zinc Dialkyl Dithiophosphate

Recent years have seen an increase in the concentration of dispersant present in formulated engine oils, while the concentration of antiwear additives has been progressively reduced. However, it is known that the presence of dispersant can, in some cases, detract from the performance of antiwear additives in lubricant blends. In this article, the influence of three succinimide dispersants on the film formation and wear-reducing properties of a secondary zinc dialkyldithiophosphate (ZDDP) has been studied. Both posttreated and non-post-treated dispersants reduce steady-state ZDDP tribofilm formation to a certain extent depending on the dispersant concentration. At very high dispersant concentrations, ZDDP film formation is suppressed almost entirely. This can be restored only marginally by increasing ZDDP concentration, which implies that the absolute dispersant concentration rather than the dispersant : ZDDP ratio controls the impact of the dispersant on ZDDP film formation. Addition of dispersant to ZDDP also caused an increase in wear rate for all three dispersants tested. For one succinimide reported in detail in this article, it is has been shown that the wear rate increases approximately linearly with dispersant concentration and is largely independent of ZDDP concentration over the P weight percentage range studied.

Accelerating dissipative particle dynamics with multiple GPUs

Dissipative particle dynamics (DPD) simulation is implemented on multiple GPUs by using NVIDIA’s Compute Unified Device Architecture (CUDA) in this paper. Data communication between each GPU is executed based on the POSIX thread. Compared with the single-GPU implementation, this implementation can provide faster computation speed and more storage space to perform simulations on a significant larger system. In benchmark, the performance of GPUs is compared with that of Material Studio running on a single CPU core. We can achieve more than 90x speedup by using three C2050 GPUs to perform simulations on an 80∗80∗80 system. This implementation is applied to the study on the dispersancy of lubricant succinimide dispersants. A series of simulations are performed on lubricant–soot–dispersant systems to study the impact factors including concentration and interaction with lubricant on the dispersancy, and the simulation results are agreed with the study in our present work.

Frictional Properties of Automatic Transmission Fluids: Part I—Measurement of Friction–Sliding Speed Behavior

For a wet clutch in an automatic transmission to operate efficiently and smoothly, it is essential that the friction in the clutch contact be high over the whole sliding speed range and also increase with sliding speed. This is achieved by careful design, both of the friction disc material and morphology and of the automatic transmission fluid. This article describes the development and use of a new test rig, based on a mini-traction machine (MTM), to measure the impact on wet clutch friction versus sliding speed properties of a range of additive solutions as well as a fully formulated automatic transmission fluid (ATF). It is found that most organic friction modifiers reduce friction at low sliding speed, whereas succinimide dispersants and some sulfonate detergent additives raise friction over the whole speed range. Overbased and neutral detergents give almost identical friction curves, indicating that, although a calcium carbonate film is deposited on the steel ball when overbased detergent is present, this does not influence friction, which is controlled by the alkyl group on the sulfonate. When long- and medium-chain surfactants are blended in proportions likely to result in a mixed adsorbed film, the resultant blends give higher low-speed friction than either individual surfactant, suggesting that the homogeneity of the adsorbed film plays an important role in determining its low-speed friction behavior. In a companion article, Part II, these results are used in combination with other work and analysis to identify the mechanism by which formulated ATFs are able to provide high friction that increases with sliding speed (Ingram, et al. ( 1 )).

Micellization and Adsorption of a Series of Succinimide Dispersants

The efficiency of a series of nonionic dispersants at stabilizing carbon-rich particles in oil was evaluated. The dispersants were synthesized by coupling a polyamine to two polyisobutylenes terminated at one end with a succinic anhydride (PIBSA). Their chemical composition was characterized by FTIR absorption. The associative strength of the dispersants was determined from their ability to self-associate in solution into reverse micelles. Their critical micelle concentration (CMC) and aggregation number (Nagg) were determined by fluorescence in an apolar solvent, namely hexane. The associative strength of the dispersants was found to increase with increasing number of secondary amines in the polyamine core. The adsorption isotherms describing the adsorption of the dispersants onto carbon black particles were determined and showed the existence of two binding regimes for the dispersants having more amines in their polar core. Much stronger binding occurred at dispersant concentration lower than the CMC. The weaker binding observed at dispersant concentrations larger than the CMC is believed to result from the dispersants having to compete between micellization and adsorption at concentrations above the CMC.

Temperature effects on the rheological properties of carbon nanotube-in-oil dispersions

The rheological behaviors of the nanotube-in-oil dispersions stabilized by polyisobutylene succinimide (PIBSI) dispersants are studied at different temperatures. Abnormal viscosity increase happens in the nanotube dispersion containing long chain dispersant (molecular weight 1000) at high temperature due to flocculation of the nanoparticles. Desorption of the dispersant molecules from solid surface is proved not to be the reason by FTIR measurement. Short chain polymer dispersant (molecular weight 550) cannot disperse nanotube well at room temperature which indicates that the shorter dispersant chain lead to the flocculation of nanotubes in the dispersions. Long chain dispersant molecules shrink at high temperature, however, the change of the dispersant conformation at high temperature is not the only reason for the flocculation behaviors. The long chain polymer may also contribute to the creation of the network structure in the dispersion at high temperature. Dispersant concentration and dispersing energy are the important factors to affect the flocculation process of the dispersion at high temperature.