Showing papers on "Viscometer published in 2016"

Experimental study of nanoparticle-surfactant-stabilized CO2 foam: Stability and mobility control

Abstract: CO 2 injection has proved to be the most common and efficient enhanced oil recovery techniques which leads to more residual oil recovery. Unfavorable sweep efficiency which results in fingering propagation and causes early gas breakthrough is the most challenging issue of gas flooding process. The aim of this work is to study foam stability and analyze the mobility of CO 2 foam stabilized by mixture of raw silica nanoparticles and ethyl hexadecyl dimethyl ammonium bromide (cationic surfactant). The result is obtained through both dynamic and static techniques using a new adsorption index. NPS-stabilized foams are generated using Ross-Miles method. A novel index for the adsorption of surfactant molecules on the nanoparticles is proposed using electrical conductivity measurement. Analyzing the foam decay behavior based on this adsorption index, it is found that the foam life can be divided into two general regions. First, low adsorption region that the foam stability is initially dominated by surfactant concentration and after a while it is controlled by nanoparticles. Second, high adsorption region, that the foam stability, is mostly affected by both nanoparticles and surfactant concentrations as well. The pressure behavior and morphology of the foam are investigated using dynamic characterization apparatus. By using a capillary viscometer in this apparatus, foam apparent viscosity is measured for different phase ratios, and nanoparticle and surfactant concentrations. It is observed that NPS solutions produce uniformly smaller foams with higher apparent viscosity compared to those with surfactant solutions. The results reveal that in different surfactant concentrations, the apparent viscosity of NPS-stabilized foam experiences a maximum value of 6.03 cp which is about 9 times larger than that of CO 2 /water dispersion flood. This maximum is coincided with the maximum adsorption index and the maximum hydrophobicity.

Density and Viscosity Measurements for Binary Mixtures of 1-Ethyl-3-methylimidazolium Tetrafluoroborate ([Emim][BF4]) with Dimethylacetamide, Dimethylformamide, and Dimethyl Sulfoxide

Abstract: The density and viscosity data of three binary liquid mixtures containing the ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate and organic solvents, dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) were obtained under atmospheric pressure, at temperatures of 303.15 to 333.15 K over the entire composition range. A vibrating-tube digital density meter and a capillary viscometer were used for density and viscosity measurements, respectively. Excess molar volumes (VE) and viscosity deviations (Δη) for the binary mixture system were calculated from the experimental data and were satisfactorily fitted with the Redlich–Kister equation. Adding DMAC, DMF, and DMSO led to negative values of VE and Δη. This finding revealed that the packing of the constituents was more efficient, and the anion–cation interaction of IL was decreased in the binary liquid mixtures. The sequences of VE and Δη for the three binary liquid mixtures in this study are also discussed using interm...

A thermoresponsive fluorescent rotor based on a hinged naphthalimide for a viscometer and a viscosity-related thermometer

Abstract: A new fluorescent smart unit (BNAP) based on bisnaphthalimide was designed and synthesized, in which two naphthalimide segments were conjugated through a twisted single bond at the 4-site. With the dual naphthalimide planes, BNAP can act as a double-channel rotor, which can output the shorter emission in the twisted state and the longer emission in the planar state. Because of the restriction of intramolecular rotation (RIR) effects, BNAP showed strong emission character in high viscosity circumstances. The longer and moderate emission in aggregates is attributed to the synergetic effects of RIR and intramolecular planarization. As a molecular rotor with dramatic changes in both emission wavelength and intensity, BNAP could be developed for the rapid detection of viscosity. The probe generates a logarithmic response to the viscosity of a glycerol/water system with different ratios. Furthermore, the probe exhibits high sensitivity to viscosity-related temperature variations. This property is very important because temperature always changes the surrounding viscosity in many biological systems and mechanical systems.

Rheological investigations of water based drilling fluid system developed using synthesized nanocomposite

Abstract: In the present study, polyacrylamide grafted xanthan gum/multiwalled carbon nanotubes (PA-g-XG/MWCNT) nanocomposite was synthesized by free radical polymerization technique using potassium persulfate as an initiator. The polyacrylamide was grafted on xanthan gum backbone in the presence of MWCNT. The synthesized nanocomposite was characterized by X-ray diffraction technique (XRD), and Fourier transform infrared spectroscopy analysis (FT-IR). The morphological characteristics of the nanocomposite were analyzed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) analyses. Also, its temperature resistance property was observed with Thermogravimetric analysis (TGA). The effect of nanocomposite on the rheological properties of the developed drilling fluid system was analyzed with a strain controlled rheometer and Fann viscometer. Flow curves were drawn for the developed water based drilling fluid system at elevated temperatures. The experimental data were fitted to Bingham, power-law, and Herschel Bulkley flow models. It was observed that the Herschel Bulkley flow model predict the flow behavior of the developed system more accurately. Further, nanocomposite exhibited non-Newtonian shear thinning flow behavior in the developed drilling fluid system. Nanocomposite showed high temperature stability and had a significant effect on the rheological properties of the developed drilling fluid system as compared to conventionally used partially hydrolyzed polyacrylamide (PHPA) polymer.

Viscosity of liquid Ag-In-Sb-Te: Evidence of a fragile-to-strong crossover

Abstract: The temperature-dependent viscosity η(T) is measured for the equilibrium liquid of the chalcogenide Ag-In-Sb-Te (AIST), the first time this has been reported for a material of actual interest for phase-change memory. The measurements, in the range 829-1254 K, are made using an oscillating-crucible viscometer, and show a liquid with high fragility and low viscosity, similar to liquid pure metals. Combining the high-temperature viscosity measurements with values inferred from crystal growth rates in the supercooled liquid allows the form of η(T) to be estimated over the entire temperature range from above the melting point down to the glass transition. It is then clear that η(T) for liquid AIST cannot be described with a single fragility value, unlike other phase-change chalcogenides such as liquid Ge-Sb-Te. There is clear evidence for a fragile-to-strong crossover on cooling liquid AIST, similar to that analyzed in Te85Ge15. The change in fragility associated with the crossover in both these cases is rather weak, giving a broad temperature range over which η(T) is near-Arrhenius. We discuss how such behavior may be beneficial for the performance of phase-change memory. Consideration of the fragile-to-strong crossover in liquid chalcogenides may be important in tuning compositions to optimize the device performance.

Influence of MgO/Al2O3 Ratio on Viscosity of Blast Furnace Slag With High Al2O3 Content

Abstract: The viscosity of SiO2−CaO−MgO−Al2O3−TiO2−FeO blast furnace (BF) slag system with high Al2O3 content is studied by using a rotating cylinder viscometer. The effect of the MgO/Al2O3 ratio on the viscosity, the stability, and break point temperature of BF slag are investigated. As a result, an increase in the Al2O3 content and a decrease of temperature tended to make the stability of slag become worse gradually due to an increase in the degree of the polymerization of the slag. In addition, increasing Al2O3 content results in an increase in viscosity at a fixed temperature. The MgO/Al2O3 ratio of the slag have obvious effect on the influence of the temperature of the BF slag on viscosity of the slag; the proper use of the MgO/Al2O3 ratio can obviously improve the stability and the fluidity of the slag, and the suitable value of the MgO/Al2O3 ratio decrease with increasing the Al2O3 content in the BF slag. In order to maintain a good stability and fluidity of the slag, the Al2O3 content in the slag should be 18% not exceed 19% and the ration of MgO/Al2O3 in a range of 0.6–0.7.

A stress-controlled microfluidic shear viscometer based on smartphone imaging

Abstract: We report a stress-controlled microfluidic shear viscometer with flow visualization aided by smartphone technology. The method involves driving the fluid into a microchannel at constant pressure and using the smartphone camera to track the fluid front in a glass capillary attached to the microchannel. We find that videos of interface propagation from the smartphone are of sufficient resolution that accurate pressure drop-flow rate relations can be determined to quantify the viscosity curves for complex fluids. We demonstrate that this simple ‘iCapillary’ device measures the shear viscosity of Newtonian and polymeric fluids over a broad range of shear rates (10–10,000 s−1) that is in quantitative agreement with rotational rheometry. We further show that the simplicity of the iCapillary device allows for parallel analysis of viscosity of several samples. We performed multiplexed measurements of concentration dependence of high shear rate viscosity of globular protein solutions, and the results are in good agreement with models of suspension rheology as well as prior experimental data. Our approach is unique, since no on-chip sensing element is required other than the smartphone camera. This sensor-less approach offers the potential to create inexpensive and disposable devices for point-of-care rheology of complex fluids and biological samples.

Thermophysical properties of ethylene glycol-water mixture containing silver nanoparticles

Abstract: In the present work, we report the thermophysical properties of ethylene glycol and water mixture based silver nanofluids. The thermo physical properties such as thermal conductivity, viscosity, density and specific heat are measured using KD2 Pro thermal properties analyser, capillary viscometer, electronic weighing balance and differential scanning calorimeter respectively. The thermal conductivity increases with the increase in particle concentration and temperature. The maximum enhancement of thermal conductivity observed is approximately ~12% for 0.15 vol% at 50°C. The higher thermal conductivity of the particle, Brownian motion and clustering of the particles could be the possible reason for the improvement in thermal conductivity of the nanofluid which is consistent with the published literature. The viscosity and density increases with increase in particle concentration and decreases with increase in temperature. The specific heat decreases with increase in particle concentration and increases with increase in temperature.

Self-assembly properties of a temperature- and salt-tolerant amphoteric hydrophobically associating polyacrylamide

Abstract: We prepared amphoteric hydrophobically associating polyacrylamides (AHAPAM) consisting mostly of hydrophilic polyacrylamide backbones, but also including the ionic hydrophobic monomer N,N-dimethyl octadeyl allyl ammonium chloride (DOAC) and the anionic monomer sodium 4-styrenesulfonate (SSS). The AHAPAM copolymer was prepared by carrying out aqueous solution polymerization. Macroscopic and microscopic self-assembly properties of AHAPAM in solution, as well as the effects of salt, temperature, and shearing on its association behavior were studied by carrying out viscosimetry, rheology, fluorescence spectroscopy (FS), and environmental scanning electron microscopy (ESEM) analyses. The results show that the association of the aqueous copolymer solutions were greatly affected by the concentration of the copolymer. The critical association concentration (CAC) of the AHAPAM solution was found to be 0.165 wt%, which was determined by carrying out viscometry and fluorescence spectroscopy experiments. Adding sodium chloride resulted in an increase in the apparent viscosity, which corresponded to the anti-polyelectrolyte solution behavior of AHAPAM. Meanwhile, intermolecular hydrophobic associations helped AHAPAM form a dynamic physically crosslinked network in its structure, conferring on AHAPAM strong heat- and shearing-resistance properties. The apparent viscosity of the 0.5 wt% copolymer solution was maintained at 92 mPa s at 140 °C and 170 s−1 shearing for 1 h. FTIR and 1H NMR spectra indicated the structure of the hydrophobically associating copolymers. And using the dilution extrapolation method, the intrinsic viscosity [η] of AHAPAM was shown to be 858.5 mL g−1.

Viscosities of Fatty Acid Methyl and Ethyl Esters under High Pressure: Methyl Myristate and Ethyl Myristate

Abstract: Viscosity have been measured in ethyl myristate (C16H32O2) and methyl myristate (C15H30O2) at pressures up to 100 MPa along isotherms ranging from 293.15 to 403.15 K. The measurements were carried out by using a falling-body viscometer as well as a quartz crystal resonator viscometer. A comparison made between both sets of data reveals a good agreement with the different viscometers. Based on the data provided, high pressure correlations are proposed to represent viscosity in terms of density and temperature within the expanded experimental uncertainty. In addition a scaling method is given to relate the viscosity to a single thermodynamic quantity.

Microfluidic Diffusion Viscometer for Rapid Analysis of Complex Solutions

Abstract: The viscosity of complex solutions is a physical property of central relevance for a large number of applications in material, biological, and biotechnological sciences. Here we demonstrate a microfluidic technology to measure the viscosity of solutions by following the advection and diffusion of tracer particles under steady-state flow. We validate our method with standard water-glycerol mixtures, and then we apply this microfluidic diffusion viscometer to measure the viscosity of protein solutions at high concentrations as well as of a crude cell lysate. Our approach exhibits a series of attractive features, including analysis time on the order of seconds and the consumption of a few μL of sample, as well as the possibility to readily integrate the microfluidic viscometer in other instrument platforms or modular microfluidic devices. These characteristics make microfluidic diffusion viscometry an attractive approach in automated processes in biotechnology and health-care sciences where fast measurements with limited amount of sample consumption are required.

Rheology of Water-in-Oil Emulsions with Different Drop Sizes

Abstract: Systemic experiments have been conducted to investigate the effect of drop sizes on the rheology of water-in-oil (W/O) emulsions. Three sets of emulsions with different average drop sizes were first prepared and then the corresponding rheologies were determined using a concentric viscometer. Results indicated that the flow behavior of concentrated emulsions changes qualitatively from Newtonian flow to non-Newtonian flow with shear rates. In Newtonian flow regime, a smaller drop size leads to a higher viscosity, and the increments are more pronounced at high dispersed phase volume fractions. Two local remarkable increases of the emulsion viscosity with dispersed phase volume fractions correspond to the percolation and glass-transition, respectively. In non-Newtonian flow regime, emulsions show shear-thinning behavior and can be fitted well by the power law model. For emulsions with volume fractions between 0.132 and 0.325, the flow index and consistency constant show power law relationship with the water c...

Rheology of an Ionic Liquid with Variable Carreau Exponent: A Full Picture by Molecular Simulation with Experimental Contribution

Abstract: The rheological behavior of an ionic liquid was investigated by means of molecular dynamics simulations with experimental contribution, under conditions close to those found in the elastohydrodynamic and the very-thin film lubrication regimes. The molecular model was applied to nearly 200 temperature–pressure–shear rate cases, without any parameter adjustment. Experiments were conducted on a rheometer and a high-pressure falling-body viscometer. This unique combination of numerical and experimental tools has enabled the full description of the ionic liquid rheological response to extreme conditions of temperature, pressure and shear rate. In the linear domain, a very good consistency between the two computational approaches (nonequilibrium molecular dynamics, equilibrium molecular dynamics via the Green–Kubo formalism) and the experiments was obtained on the Newtonian viscosity. Reliable values of the pressure–viscosity coefficient, another rheological characteristic necessary for predicting film thickness in the regimes of interest in this work, were inferred. Compared with a conventional lubricant of almost identical Newtonian viscosity, the pressure–viscosity coefficient of the ionic fluid is much lower, its variations with temperature remaining, however, very similar. The application of the time–temperature–pressure superposition principle and the regression to the Carreau equation for describing the nonlinear domain have revealed, for the first time, significant variations in the exponent of the Carreau model which have been correlated with the changes in temperature and pressure.

Rheological characteristics of foamed gel for mine fire control

Abstract: SUMMARY Foamed gel as a new type of fire extinguishing material is used to prevent the spontaneous combustion of coal. In order to make a comprehensive study on rheological characteristics of foamed gel for mine fire control, by using type NDJ-5s digital viscometer, the factors such as mass concentration of the mixture mixed by thickener and crosslinker, foaming multiple, added salts (NaCl, CaCl2, AlCl3), pH value and temperature having influences on the rheological properties of foamed gel have been investigated in this paper. It can be found that foamed gel shows the characteristic of non-Newtonian fluids and has shear-thinning properties. With increasing of mass concentration of the mixture, the thixotropy response becomes more significant. When the foaming multiple reaches 20, the apparent viscosity gets the maximum value. The obvious viscosity characteristic of ‘polyelectrolyte solution’ is observed in aqueous salt solutions when added salts are put into the solution. Under different conditions of pH values, foamed gel has higher sensitivity to acid than alkaline. Zero shear viscosity, depending on temperature, decreases with the temperature increasing. Meanwhile, the fire performances of foamed gel are studied experimentally and theoretically. Copyright © 2014 John Wiley & Sons, Ltd.

On the rheology of oil (Review)

Abstract: Current ideas concerning oil rheology, in particular, that of heavy oils and water–oil emulsions have been considered. It has been shown that petroleum in general is a viscoplastic medium, whose rheological properties in many cases are satisfactorily described in terms of the simple Bingham model. Typical characterization of rheological properties reduces to measurement of the yield point and the pour point and to conditional values obtained by measuring viscosity in viscometers of various types. However, both the yield stress and plastic viscosity are structurally sensitive, resulting in dependence of the rheological properties of oil on the temperature and deformation history, including the kinetics of cooling, which is characterized by a hysteresis curve in the measurement of viscosity. The kinetics of change in the rheological properties of oil depends on the concentration of crystallizable paraffins and other components. Rheology is modified largely by introducing pour point depressants into the oil. Another method for controlling the rheological properties of oil is to convert it into the state of water–oil emulsion using various surfactants. The general formulation of the problem of pipeline oil transport has been discussed, involving calculation based on the knowledge of both the rheological properties of oil and the kinetics of transient structuring processes. The latter is especially important for start-up modes of pipeline operation.