Increase In Kinematic Viscosity Research Articles

Thermal aging performance of soybean insulating oil mixed with glyceryl triacetate

A method of delaying the aging of natural ester oil-paper insulation systems by adding glyceryl triacetate is proposed in this work. A study was conducted on the thermal aging performance of soybean insulating oil mixed with glyceryl triacetate at a volume fraction of 7.5%. Through a 42-day accelerated thermal aging experiment, it was found that the addition of glyceryl triacetate effectively delayed the increase in kinematic viscosity of the insulating oil and reduced the generation of aging products such as moisture and acid. However, the polar compounds in glyceryl triacetate reduced the breakdown voltage of the mixed oil and made the dielectric loss factor higher than that of pure oil. In addition, tests were conducted on the insulating paper immersed in two types of oil, and it was found that the addition of glyceryl triacetate helps to distribute mixed oil molecules on the surface of insulating paper, which effectively helped absorb moisture from the paper, weakening the hydrolysis reaction of cellulose and delaying the aging of insulating paper. In addition, the insulating paper immersed in the mixed oil maintains good power frequency breakdown voltage and dielectric properties throughout the thermal aging experiment.

On the evolution of turbulent boundary layers during flame–wall interaction investigated by highly resolved laser diagnostics

The turbulent boundary layer behavior in the presence of flame–wall interactions (FWI) has an important role on the mass and energy transfer at the gas/solid interface. Detailed experiments resolving the turbulent boundary layer evolution in the presence of FWI are lacking, which impedes knowledge. This work presents a combination of particle image velocimetry (flow field), dual-pump coherent anti-Stokes Raman spectroscopy (gas temperature), and OH laser induced fluorescence (flame topology) measurements to study the evolution of the boundary layer structure in the presence of FWI. Experiments are conducted in a side-wall quenching (SWQ) burner. Findings reveal that the reacting boundary layer flow adheres to the linear scaling law u+=y+ in the viscous sublayer until y+ = 5. Beyond y+ = 5, the flame modifies the velocity and temperature field such that the uz+ streamwise velocity deviates from the viscous sublayer and the law-of-the-wall scaling in the log-layer with uz+ being smaller than that of the non-reacting flow (the subscript z refers to the streamwise coordinate and is used throughout this manuscript). As the fluid approaches the flame impingement location at the wall, the gas temperature increases significantly, causing a threefold increase in kinematic viscosity, ν. Although the near-wall streamwise velocity gradient d〈Uz〉/dy|y=0mm decreases, the larger increase in ν reduces uz+ and leads to the deviation from the law-of-the-wall. Downstream the flame impingement location, ν is relatively constant and uz+ values begin to approach those of the law-of-the-wall. Trends are presented for SWQ and head-on quenching flame topologies, and are intended to help development of more accurate wall models.

Synthesis and characterization of synthetic lubricants based on dibasic acid

AbstractSynthetic esters have long been used in a variety of applications due to their excellent thermal stability, excellent cleanliness, natural lubricity, and polarity. In the present work, we aimed to prepare some synthetic base oils through preparation of different dibasic esters by esterification of dicarboxylic acids (adipic acid and azelaic acid) with different linear alcohols (hexanol, octanol, and decanol) and branched alcohol (2‐ethyl hexanol) at 120°C. The reaction yield ranges between 85% and 94%. Fourier‐transform infrared spectroscopy (FT‐IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy were used to analyze the structures of the produced compounds. Using thermo gravimetric analysis (TGA), the heat stability of the produced esters was determined, and it was found that the prepared esters have high thermal stability. The degradation of the prepared esters takes place in the range between 300 and 600°C. The rheological behaviour of prepared esters shows Newtonian behaviours, which means that Newtonian fluids obey viscosity Newton's law. The viscosity is independent of the shear rate. The results showed that the lubricity properties, based on their pour point, flash point, and oxidation stability of the esters, were significantly affected by the linear and branched alcohols used. There is a slight increase in kinematic viscosity and viscosity index values with decreasing the internal chain length of the dibasic acid. The esters which were based on adipic acid such as C1 exhibited maximum values of VI: 187 compared to those which were based on azelaic acid such as F1 with VI: 182. Viscosity and viscosity index increases with increasing the number of carbon atoms of the used mono‐ol alcohols. Using branched alcohols gave almost the same viscosity results compared to using linear alcohol with the same number of carbons. Almost all prepared esters give pour point results ≤ −30°C.

Contamination of engine oils during winter vehicle operation

Introduction. The reliability and service life of an engine is largely dependent on the quality of the engine oil. Without oil at the proper level of performance, an internal combustion engine can suffer from wear and tear, which in many cases can lead to engine failure. One of the factors in the loss of the quality level of engine oil is its contamination. For example, kinematic viscosity will gradually increase as the engine oil becomes contaminated with soot, dirt and sludge; or it may be oxidized. If the viscosity of the engine oil is too high, the engine must do extra work to overcome the increased viscosity resistance.Fuel and water dilution is one of the most common contaminants in diesel engines.Materials and Methods. The paper presents the results of a study of the combined effect of water and diesel fuel on synthetic engine oil at their various concentrations. The influence evaluation of contaminants on changes in the performance characteristics of the lubricant, such as: kinematic viscosity at 40° C (measurement was carried out on an automatic Stabinger SVM 3000 viscometer), base and acid numbers (values obtained using an automatic Titroline Alpha 20 Plus titrator), as well as concentration measurement elements - indicators of engine oil on an optical emission spectrometer with inductively coupled plasma of the iCAP 7000 series.Conclusions. The presence of contaminants in the engine oil leads to an increase in kinematic viscosity, during the operation of the engine oil, the value of its base number becomes less, and the value of the acid, on the contrary, increases. It is necessary to replace engine oils when the base number decreases by 50% or according to the balance of base and acid numbers.Scope of Study/Opportunity. This type of low temperature performance modelling provides insight into how the oil deteriorates and evaluates the change in oil performance during use.Originality/value. The study can be the basis for developing recommendations for improving the maintenance of internal combustion engines for enterprises that have cars with diesel engines at their disposal in order to increase the resource of power units and reduce operating costs.

Study on the thickening behavior and mechanism of supercritical CO2 by modified polysiloxane

Supercritical CO2 has been widely concerned because of its clean environmental protection and excellent performance. However, the low viscosity limits its wide application. To this issue, researchers usually use thickeners to improve its viscosity. The siloxane-type polymer is regarded as clean and cheap thickener. In this work, we screened potential supercritical CO2 thickeners by comparing the thickening properties of vinyl polysiloxane, hydroxyl polysiloxane and polydimethylsiloxane. The results show that vinyl polysiloxane has the best thickening performance. The dissolution and thickening behavior of vinyl polysiloxane are further studied. The results indicate that the dissolution pressure and thickening capacity of vinyl polysiloxane in supercritical CO2 increase with the increase of kinematic viscosity and concentration. At the experimental conditions, the maximum viscosity of supercritical CO2 can be increased to 14.87 mPa·s. In addition, the dissolution pressure of vinyl polysiloxane in supercritical CO2 decreases with the increase of cosolvent concentration, while the viscosity slightly decreases. Finally, the thickening mechanism of these thickeners was studied by molecular dynamics simulation. Based on the molecular simulation results, the roles of functional groups of thickeners in the dissolution and thickening process are discussed. It can provide theoretical support for the synthesis and screening of CO2 thickeners in the future.

Vortex breakdown in variable-density gaseous swirling jets

Theoretical predictions and numerical simulations are used to determine the transition to bubble and conical vortex breakdown in low-Mach-number laminar axisymmetric variable-density swirling jets. A critical value of the swirl number $S$ for the onset of the bubble ( $S^*_B$ ) and the cone ( $S^*_C$ ) is determined as the jet-to-ambient density ratio $\varLambda$ is varied, with the temperature dependence of the gas density and viscosity appropriate to that of air. The criterion of failure of the slender quasi-cylindrical approximation predicts $S^*_B$ that decreases with increasing values of $\varLambda$ for a jet in solid-body rotation emerging sharply into a quiescent atmosphere. In addition, a new criterion for the onset of conical breakdown is derived from divergence of the initial value of the radial spreading rate of the jet occurring at $S^*_C$ , found to be independent of $\varLambda$ , in an asymptotic analysis for small distances from the inlet plane. To maintain stable flow in the unsteady numerical simulations, an effective Reynolds number $Re_{eff}$ , defined employing the geometric mean of the viscosity in the jet and ambient atmosphere, is fixed at $Re_{eff}=200$ for all $\varLambda$ . Similar to the theoretical predictions, numerical calculations of $S^*_B$ decrease monotonically as $\varLambda$ is increased. The critical swirl numbers for the cone, $S^*_C$ , are found to depend strongly on viscous effects; for $\varLambda =1/5$ , the low jet Reynolds number (51) at $Re_{eff}=200$ delays the transition to the cone, while for $\varLambda =5$ at $Re_{eff}=200$ , the large increase in kinematic viscosity in the external fluid produces a similar trend, significantly increasing $S^*_C$ .

E-Axle用潤滑油下における軸受鋼の転がり摩擦挙動

To extend the cruising range of electric vehicles (EV), it is necessary to improve the power consumption rate. By rotating the motor at high speed, it is possible to reduce the size and the weight of E-Axle, which improves the power consumption rate. However, high-speed rotation increases the number of contacts between gear tooth flanks in E-Axle reduction gears. This promotes the fatigue of the bearings and gears. Additionally, the lubricant has been newly developed for E-Axle, will be used instead of existing automatic transmission fluid. However, the effects of E-Axle lubricants on the fatigue of tooth surfaces have not been elucidated. In addition, on the contact surface of gears, sliding and rolling contact cause stress at the same moment. To evaluate the occurrence factors of fatigue in detail, it is necessary to divide the contact types into sliding and rolling contact and investigate the fatigue on contact surfaces. In this study, we focus on occurrence of pitting by only rolling contact to investigate fatigue factors. In this experiment, ball-on-disk type fatigue tests are conducted to evaluate performances of five different E-Axle lubricants for the occurrence of pitting under pure rolling condition. The results showed that pitting was reduced effectively with the lubricant that has the lowest kinematic viscosity. In addition, the pitting rates increase as the increase of kinematic viscosity. Therefore, the kinematic viscosity is considered to influence the occurrence of pitting fatigue.

ИССЛЕДОВАНИЕ ВЯЗКОСТИ БРОМСОДЕРЖАЩЕГО ПЛАСТИФИКАТОРА ИЗ ОТХОДОВ ПРОИЗВОДСТВА

The importance of studying the viscosity parameters of liquid ingredients of plastics and elastomers for solving a number of technological issues related to taking into account the energy costs required to perform basic and auxiliary production operations in the processing of polymer materials is noted. The influence of the degree of halogenation of unsaturated mixed plasticizer obtained from industrial waste on its viscosity in the temperature range corresponding to the technological parameters of processing polymer materials 273-393 K. It is shown, that with an increase in the degree of bromination at a constant temperature the viscosity of the bromine-containing plasticizer increases by 63.3%, 52.0% and 46.8%, respectively. With an increase in temperature to 353-393 K, a decrease in the maximum viscosity values for samples with a mass fraction of bromine of 14.4% by 26% was found. It is shown that in the studied range of the degree of bromination, the viscosity drop with an increase in temperature to 393 K is 96%. An equation is proposed to evaluate the effect of the degree of bromination and temperature on the viscosity of a mixed bromine-containing plasticizer of the phthalate type, obtained from production waste. The values of its coefficients in a given temperature range are established, which characterize the change in the intensity of intermolecular interaction with an increase in the bromine content in the plasticizer. It is shown that the activation energy of the viscous flow decreases by 12% with an increase in temperature and an increase in bromine content. The heat of evaporation of the plasticizer components within 100 kJ/mol was determined. The value of a complex indicator is obtained, taking into account the combined effect of bromine content and temperature on viscosity in the range of 25-26 kJ/mol, which confirms the provisions of the activation theory for linear low-molecular hydrocarbons. It was found that the degree of influence of the bromine content in the plasticizer on its viscosity in the established temperature range is 3.3 – 4.1%. It is shown that an increase in the degree of bromination of a phthalate-type plasticizer contributes to an additional intermolecular interaction that contributes to an increase in kinematic viscosity.

The Effect of Nickel on the Viscosity of Iron-Based Multicomponent Melts

In this work, we investigated the temperature dependence of the kinematic viscosity of multicomponent Fe72.5−xNixCu1Nb2Mo1.5Si14B9 melts with a Ni content of up to 12.7 at. %. The peculiarities of the temperature dependence of Ni-containing melts were explained by the tendency of Ni atoms to surface segregation. Ni atoms are concentrated near the interfaces of the liquid and solid phases in the mushy zone at the stage of melting and restrain the melting of the solid phase. With increasing Ni content, the Arrhenius type of viscous flow begins at a higher temperature. Ni atoms are concentrated at the periphery of clusters, increasing their size and decreasing their mobility. The movement of Ni-containing clusters increases the activation energy and decreases the kinematic viscosity. The change in the activation energy at a temperature of about 1700 K was associated with a liquid-liquid structure transition (LLST). This structural transition is reversible since it is observed both at the heating and cooling stages. The increase in kinematic viscosity at temperatures above 1900 K was associated with the decomposition of high-temperature clusters based on cementite and silicon oxides.

Hydromagnetic Instability of Two Viscoelastic Dusty-Fluids in Porous Medium

An attempt has been made to investigate the instability of the plane interface between two viscoelastic superposed conducting fluids in the presence of suspended particles and variable horizontal magnetic field through porous medium is studied. The cases of two fluids of uniform densities, viscosities, magnetic fields, and suspended particles number densities separated by a horizontal boundary; and of exponentially varying density, viscosity, suspended particles number density, and magnetic field are considered. It is found that the stability criterion is independent of the effects of viscoelasticity, medium porosity, and suspended particles but is dependent on the orientation and magnitude of the magnetic field. The magnetic field succeeds in stabilizing a certain range of wavenumbers which were unstable in the absence of the magnetic field. The system is found to be stable for potentially stable configuration/stratification. The growth rates are found to increase (for certain wavenumbers) and decrease (for other wavenumbers) with the increase in kinematic viscosity, suspended particles number density, magnetic field, medium permeability and stress relaxation time.

Parametric studies on the storage stability and aging effect of biodiesel treated with Eucalyptus oil as a cost‐effective green‐antioxidant additive

Oxidation stability is one of the most significant fuel quality standards for biodiesel and mainly distresses the stability of biodiesel. Therefore, the present work aims to report the Eucalyptus oil (EO) as a natural green antioxidant additive to evaluate the oxidation stability of biodiesel produced from dairy waste scum, Bauhinia variegata and Butea monosperma oil. The obtained results have also been compared with the conventional synthetic antioxidant, butylated hydroxy toluene (BHT). The oxidation stability of the biodiesel treated with these additives was evaluated using the professional biodiesel Rancimat instrument. Further, the fuel properties kinematic viscosity and acid value were measured during the storage period. The obtained results showed an increase in the induction period in the biodiesel sample treated with EO, indicating a protective effect and inhibiting the oxidation initiation step. As a result, the oxidation stability of dairy waste scum methyl ester (DWSME), B variegata methyl ester (BVME) and B monosperma methyl ester (BMME) was found to be ~10, ~8 and ~8 hours, respectively, during 90 days storage when the natural antioxidant EO with a concentration of 4000 ppm was used and these obtained values were in the limit of EN 14214 standard. Interestingly, these values were found to be on par with the oxidation stability of DWSME (~11 hours), BVME (~9 hours) and BMME (~9 hours), when the synthetic antioxidant BHT was used with a concentration of 3000 ppm during the 90 days storage. Although the addition of EO as antioxidant resulted in increase in kinematic viscosity and acid value of the biodiesel samples, those values well-fall in the ASTM 6751 standard limit. On the other hand, synthetic antioxidant BHT showed enhanced results as compared to the EO. However, the effectiveness of the proposed natural antioxidant additive (EO) is on par with the synthetic antioxidant (BHT), which can be replaced for cost-effectiveness, non-toxic and safer consumption of biodiesel as compared to synthetic antioxidant-treated biodiesel.

Investigation of changes in the properties of engine oil depending on the sulfur content in gasoline

In exploitation of modern cars, there are cases of power unit failure due to a sharp deterioration in the properties of engine oil and loss of performance of the lubricant. The article describes the causes of failures of the engines of modern cars associated with the loss of the resource of oil in the engine and the processes occurring in the lubricant. They are increase of kinematic viscosity, decrease of Total Base Number, increase of the acid number, decrease of flash point, increase of water content, decrease of additives content, increase of wear products. Decrease in properties and motor oils lifetime was caused primarily by the deviation of the physicochemical parameters of applied motor gasoline beside regulatory petrol. The process and chemical reaction of sulfurous acid formation during engine operation are described. We have established a pattern of changes in physico-chemical parameters of motor oils in automotive gasoline sulfur compounds. Made quantification is produced by the combustion of 1 kg of gasoline sulfur acid. The low values of the loss of the alkaline number of motor oil, caused by the low sulfur content of the ecological class 5 gasoline, are a prerequisite for an increase periodicity of oil change in the operation of modern cars.

Effects of Nanoparticles Materials on Heat Transfer in Electro-Insulating Liquids

This paper discusses the effect of doping of electro-insulating liquids with nanoparticle materials on the thermal properties of the obtained nanoliquids and heat transport in the transformer. Mineral oil, synthetic ester, and natural ester were used as base liquids. The effectiveness of doping base liquids with nanoparticles was supported by ultraviolet-visible (UV/VIS) measurements. In turn, Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) confirmed the absence of intermolecular interactions (i.e., hydrogen bonding). The influence of modification of electro-insulating liquids with fullerene C60 and titanium dioxide TiO2 nanoparticles on such thermal properties as thermal conductivity, specific heat, kinematic viscosity, density, and thermal expansion was investigated. Based on these properties and the theory of similarity, the cooling efficiency of the transformer filled with the analyzed nanofluids was determined. Nanofluids’ cooling effectiveness was compared with the cooling effectiveness of the base liquids. This comparison was supported by an analysis of Grashof, Prandtl, and Nusselt numbers. It has been shown that the modification of electro-insulating liquids with nanoparticles widely used in order to improve their dielectric properties, such as C60 and TiO2, does not have a significant influence on their thermal properties. The addition of fullerene C60 caused an increase in kinematic viscosity, which was compensated by the increase in specific heat. In the case of TiO2, the addition of this nanoparticle resulted in an increase in kinematic viscosity and a decrease in specific heat, which were balanced out by the increase in thermal conductivity. In summary, the heat exchange-capacity of liquids did not change due to doping with nanoparticles.

Solubilities of CO2 in, densities and kinematic viscosities of poly(propylene glycol) diglycidyl ether and poly(ethylene glycol) monooleate

Densities and kinematic viscosities of polymer absorbents such as poly(propylene glycol) diglycidyl ether(PPDE) with molecular weights of 380 and 640, and poly(ethylene glycol) monooleate(PEGM) with molecular weight of 460 were respectively measured at atmosphere and temperatures ranging from 273.15 K to 333.15 K, and correlated with linear equation and Vogel-Fulcher-Tamman equation respectively. The density declines slightly while the kinematic viscosity decreases greatly with the increase of temperature. The result also showed that increasing the molecular weight is beneficial for the decrease of density and the increase of kinematic viscosity. In addition, CO2 solubilities in the selected polymer absorbents were determined by using an isothermal synthetic method, under pressures up to 1.2 MPa and at temperatures ranging from 273.15 K to 303.15 K. The four-parameter nonrandom two-liquid (NRTL) model was used to fit the experimental data, and model parameters were obtained. According to the absorbents as PPDE380, PEGM460, and PPDE640, the mean relative deviations of the pressure between the experimental and fitted data were 1.03%, 1.15%, and 1.31%, and the maximum deviations of that were 2.73%, 2.57%, and 2.55%. The result showed that decreasing the absorption temperature has a large effect on improving absorption capacity. Henry’s constants were calculated from NRTL model and compared with those of experimental data. Relatively good correspondence was obtained with the experimental and calculated data. To assess the selected absorbents for CO2 capture preliminarily, densities and kinematic viscosities of, CO2 solubilities in selected absorbents were compared with common solvents used in industrial plants, other polymer absorbents, and some ionic liquids. The result showed the selected absorbent as PPDE640 has moderate density and kinematic viscosity, the highest CO2 absorption capacities of all the compared absorbents, which showed that PPDE640 has potential research value for CO2 capture.

Treatment and restoration of used Mineral-Oil-Based hydraulic fluids from different machines. Part 1: Dewatering, filtration and effect of viscosity modifier

ABSTRACTIn this work, characterization and treatment of used hydraulic oil samples were performed in three steps. In the first step, the physical and the chemical properties of fresh and used hydraulic mineral oil samples from various centrifugal casting and pipe drawing machines were investigated according to ASTM D 6158. Results show that water content, solid particles count and depletion of additives have considerably affected most of the oil properties. Used oil samples failed in the appearance, thermal stability, oxidation stability, foaming tendency, water content and particles count.In the second step, a simple methodology for dewatering and filtration was adopted. This methodology involved settling, followed by dry-air bubbling for oil dehydration and finally vacuum filtration. Such process successfully removed considerable portion of solid particles and water in used oil samples. Appearance, pour point, water content, particles count, and acid number were restored to the allowable limits. While water separability, oxidation stability, thermal stability and foaming tendency still failed the limits after treatment. It is obvious that additives will be needed to restore the latter properties.In the third step, viscosity modifier additive was added to the oil samples to enhance viscous properties. A linear increase in kinematic viscosity was witnessed at 100°C, while at 40°C, an initial linear increase at low viscosities was followed by lower slopes at higher viscosities.

Problems in designing fuel installation for small turboprop aircraft

This paper discusses the problems of designing a fuel installation for the I-31T, four seat, fully composite aircraft designed in accordance with FAR 23/CS 23. The project was carried out under the European Union project entitled ESPOSA (7th Frame Programme)—“Efficient Systems and Propulsion for Small Aircraft”. I-31 Turbo has been created on the base frame of the I-23 “Manager” aircraft, through replacement of its original piston engine, the Lycoming O-360 A1A, with a TP-100 turbo shaft engine. Moreover, the front of the plane, from the bulkhead 1, was altered, while the old navigation and piloting equipment was substituted with a modern “glass cockpit”. These modifications required designing of a new fuel system within the engine chamber. The existing fuel system in the fuselage and wings was adapted for the new JET-A fuel. In order to confirm whether the installation in the wings and the fuselage would provide the consumption rate required by the TP-100 engine (a tripling of the fuel flow and a ten-fold increase in kinematic viscosity of fuel), calculations and simulations were carried out. The calculations were verified using the second I-23 aircraft, designated for static campaign tests. The ground tests studied the flow of the fuel from the auxiliary tank and were carried out under two different fuel temperatures (−20 ℃ and 20 ℃) and two different fuselage angles (0 and −10.7°). The project was documented in 3D in CATIA V5 program and in project documentation. To sum up, the main innovative element of the fuel system in the engine chamber is the module containing the pumps, filters, one-way valves, flow meter, among others. This concentration of parts allows a significant reduction in plane servicing time in between flights.

Thermal-oxidation mechanism of dioctyl adipate base oil

Abstract The ester base oil of dioctyl adipate (DOA) was oxidized in an oven at 200 °C for 30 h, and variations in the physicochemical and tribological properties were studied. To investigate the thermal-oxidation mechanism, the thermal-oxidation products were analyzed by gas chromatography–mass spectrometry (GC−MS), and the thermal-oxidation process was simulated using visual reactive force field molecular dynamics (ReaxFF MD). The results indicated that the total acid number (TAN) increased significantly because of the presence of 14% carboxylic acids and low molecular weight monoesters. The tribological properties were improved by the formation of the strongly polar carboxylic acids. Additionally, the increase in kinematic viscosity was limited due to the formation of high molecular weight polymerization products and low molecular weight degradation products. Thermal-oxidative degradation and polymerization mechanisms were proposed by combining ReaxFF MD simulations and GC−MS results.

Viscosimetric Study of Andiroba Oil-based Polyols (Carapa Guianensis Aubl)

Natural bases and alternative easy degradability have been employed in the petrochemical industry for polymer formulation, paints, foams, detergents, lubricating oils and especially, due to its viscous characteristics. The great advantage of renewable raw materials to replace fossil products prompted the study of viscosity of andiroba oil ( Carapa guianensis Aubl.) after chemical modifications. The oil was characterized by the acid number, kinematic viscosity, saponification value, moisture content, iodine index, peroxide index, oxidative stability, hydroxyl number and density, and then subjected to chemical modifications (alkaline ethyl transesterification and hydroxylation in situ). The production of andiroba polyols was optimized using factorial design, based on the reduction in the degree of unsaturation, monitored mainly by the increase in kinematic viscosity. The study of the conversion process was effective for the synthesis of polyols in different viscosity ranges, indicating the best conditions for obtaining polyols having flow characteristics compatible with commercial lubricants. DOI: 10.5935/1984-6835.20160067

Stability of Stratified Rivlin-Ericksen Fluid in the Presence of Horizontal Magnetic Field and Uniform Horizontal Rotation in Porous Medium

The influence of viscosity, viscoelasticity and medium permeability on the stability of stratified Rivlin-Ericksen viscoelastic fluid is examined for viscoelastic polymeric solutions in the simultaneous presence of a uniform horizontal magnetic field (H, 0, 0) and uniform horizontal rotation (Ω,0,0). These solutions are known as Rivlin-Ericksen fluids and their rheology is approximated by the Rivlin-Ericksen constitutive relations, proposed by Rivlin and Ericksen [13]. The effects of Coriolis forces on the stability is chosen along the direction of the magnetic field and transverse to that of the gravitational field (o,o,-g). The system is found to be stable for all wave numbers for stable stratifications and unstable for unstable stratifications for the stratifications in density, viscosity, viscoelasticity, medium permeability and medium porosity. The system can be completely stabilized by large enough magnetic field, which was unstable in the absence of magnetic field; provided the initial configuration is top-heavy density wise. The kinematic viscosity and kinematic viscoelasticity have damping effects on the growth rates with the increase in kinematic viscosity and kinematic viscoelasticity, respectively, for a fixed wave number. The medium permeability has enhancing effects on the growth rates with its increase for a fixed wave number. The above results have also been shown graphically.

Performance Evaluation of Polymer Modified Asphalt Mixtures

Attention has been increasing towards the use of polymer modified asphalt, because conventional asphalt mixtures cannot resist the high axle loads and tire pressures. Several classes of modified binders have been used in asphalt pavements. The main objective of this research was to evaluate the effect of adding several types of polymers on asphalt cement and asphalt mixtures. Experimental program involved two phases. The first phase was modifying the asphalt using six types of polymers then evaluating the properties of the modified asphalt. The second phase was evaluating the effect of binder modification on Marshall mix design and indirect tensile strength of the asphalt concrete mixtures. It was found that the optimum percentage of PVC, plastic bags and novolac was 4%, and the optimum percentage of HDPE was 5% by weight of asphalt. These percentages caused increase in kinematic viscosity, stability, and indirect tensile strength and caused reduction in penetration.