Showing papers on "Viscometer published in 2003"
TL;DR: In this article, the authors investigated the viscosity of hydrous Etna lava in order to better understand eruptive processes which characterize this volcano, and they found that at temperatures ranging from 1,050 to 1,150°C and with water contents between 0.5 and 2.3% (eruptive conditions), their results were in reasonable agreement with those calculated using Shaw's model, and much lower than those experimentally determined in a previous study.
Abstract: Water dissolved in a silicate melt can strongly influence its physical properties and thus magma behavior during crystallization, degassing, foaming and fragmentation. Etna is a basaltic volcano whose activity is dominated by effusive eruptions which have long represented a threat to the densely populated, surrounding area. Recently, recognition of the products of a Plinian eruption (122 B.C.) has raised further issues for hazard assessment at Etna and other basaltic volcanoes. Constraining the behavior of Etna magma under conditions relevant to both effusive and explosive hazards requires viscosity data under conditions near the glass transition. Here we have investigated the viscosity of hydrous Etna lava in order to better understand eruptive processes which characterize this volcano. The experimental methods which have been used include piston cylinder synthesis of the hydrated melts, micropenetration viscometry for low-temperature viscosity measurements, and near-infrared spectroscopy for the evaluation of sample homogeneity and measurements of water content. Additionally, scanning calorimetric determinations were performed to check whether incipient crystallization had occurred. Sample compositions were determined using electron microprobe analysis and 57Fe Mossbauer spectroscopy. Results from this study are compared with previous reports of trachytic, phonolitic and model calc-alkaline rhyolite (HPG8) compositions. The viscosity of the basaltic melt (dry and wet) has been parameterized in terms of temperature and water content via the non-Arrhenian equation: log10
η=–4.643+(5,812.44–427.04×H2O)/(T(K)–499.31+28.74×ln(H2O)) where η is the viscosity in Pa s, H2O is the water content in wt%, and T is the temperature in Kelvin. We observe that the viscosity of alkali basalt (at more than 0.5 wt% H2O) is similar to that of an alkaline trachyte (Agnano–Monte Spina eruption, Phlegrean Fields) and much higher than that of a peralkaline phonolite (Teide, Tenerife) at similar silica contents and NBO/T. For water contents above 1.5 wt%, the viscosity of the basalt is similar to that of rhyolitic melts with similar water contents. At temperatures ranging from 1,050 to 1,150 °C and with water contents between 0.5 and 2.3 wt% (eruptive conditions), the viscosities calculated using the equation defined in this study are (1) in reasonable agreement with those calculated using Shaw's model, and (2) much lower than those experimentally determined in a previous study. However, outside these temperature and water content ranges, the agreement with Shaw's model (1972) breaks down.
218 citations
TL;DR: In this paper, the effect of pressure and composition on the viscosity of both anhydrous and hydrous andesitic melts was studied in a parallel plate viscometer.
127 citations
TL;DR: In this article, the authors measured the viscosity of molten silicon and found that it showed a good Arrhenian behavior in the entire temperature range including the supercooled region and no abnormal increase around the melting point.
109 citations
TL;DR: In this article, the viscosity of CaMgSi2O6 (diopside) liquid has been determined up to 13 GPa and 2200 C using in situ falling sphere viscometry with X-ray radiography.
98 citations
TL;DR: In this article, in-line slit and capillary die viscometers were specially designed to study the viscoelastic behavior of plasticized wheat starch under low-hydrated conditions.
82 citations
TL;DR: The calculated rate constants indicate that degradation rate of PVA solutions decreases with increasing of solution concentration, and viscosity increases and it causes a reduction in the cavitation efficiency thus, the rate of degradation will be decreased.
76 citations
TL;DR: In this paper, the rheological properties of polyethylene glycol (PEG) binders having different molecular weights were analyzed using capillary viscometer, and the results indicated that the feedstock containing larger molecular weight PEG shows a higher yield stress and shear stress.
63 citations
TL;DR: The analytical correction procedure developed here is expected to be useful wherever the Casson model is used to describe the rheology of a fluid, particularly one exhibiting yield-stress pseudoplastic behavior.
62 citations
TL;DR: In this paper, the viscosity of saturated liquid dimethyl ether was measured over the temperature range from (227 to 343) K along the saturation line made with a calibrated capillary viscometer.
Abstract: Measurements of the viscosity of saturated liquid dimethyl ether are reported over the temperature range from (227 to 343) K along the saturation line made with a calibrated capillary viscometer. The results were correlated as a function of temperature. The standard deviation and the maximum deviation of the experimental results from the correlation equation are 0.5% and 1.3%, respectively.
49 citations
Patent•
30 Jan 2003TL;DR: In this article, a method of measuring yield stress using a standard rotating viscometer modified with a plurality of intermeshing fins such that a standard spring responds to a torque that is related to yield stress and that is imposed by a stressed test material on a portion of the fins connected to the spring.
Abstract: A conventional Couette viscometer is transformed to measure yield point, also known as yield stress, and other rheology of various fluids, including ones with particulates. A rotating viscometer includes a driven portion, a responsive body, a standard spring, and a plurality of fins. The fins have predetermined shapes such that the rotating viscometer and the standard spring, connected to the responsive body having at least a portion of the fins, are sensitive to detect yield stress of a test fluid composition in response to a selected rotation imparted to the driven portion. A method of measuring yield stress includes operating a standard rotating viscometer modified with a plurality of intermeshing fins such that a standard spring of the standard rotating viscometer responds to a torque that is related to yield stress and that is imposed by a stressed test material on a portion of the fins connected to the spring.
48 citations
TL;DR: It is evident that both the polymer solution viscosity and the molecular weight have an effect on the drug release from microsphere properties, and release rates of matrix microspheres could be predictably optimized by adjusting the viscosities of polymer solutions.
Abstract: The objectives of this investigation are to evaluate the effect of the viscosity of polymer solution phase on microsphere properties, especially the drug release characteristics since no studies on this formulation variable have been reported. Also, since it is known that polymer molecular weight affects both the viscosity of the polymer solution and the release properties of microspheres, the interaction of these factors was studied. Microspheres with 33% theoretical drug loading of anhydrous theophylline core material were prepared by the emulsion solvent evaporation method. Two cellulose acetate butyrate polymers, (CAB381-2, CAB381-20), chemically similar but having different molecular weights, were used to prepare different polymer solutions having different apparent viscosities in acetone. A Brookfield viscometer was used to evaluate the viscosities of polymer solutions. Dissolution rates of microspheres prepared from the polymer solutions were inversely related to the initial polymer solution viscosities for both CAB381-2 and CAB381-20. The times for the release of 30 and 50% of the drug from the microspheres have a linear relationship with initial polymer solution viscosity. Initial release was significantly decreased with increasing polymer solution viscosity. Unlike CAB381-2 microspheres which follow Higuchi spherical matrix release kinetics, microspheres prepared from the higher molecular weight polymer (CAB381-20) showed extended release dissolution profiles with near zero order kinetics. It is evident that both the polymer solution viscosity and the molecular weight have an effect on the drug release from microspheres. These results suggest that release rates of matrix microspheres could be predictably optimized by adjusting the viscosity of polymer solutions.
TL;DR: In this paper, the viscosity of blends of DME and various fuels and additives was characterized, including a federal low-sulfur diesel fuel, soybean oil, biodiesel, and various lubricity additives, over a range of blend ratios.
Abstract: Dimethyl ether (DME) is a potential ultra clean diesel fuel. Dimethyl ether burns without producing the smoke associated with diesel combustion and can be manufactured from synthesis gas or methanol. However, DME has a low viscosity compared to diesel fuel and has insufficient lubricity to prevent excessive wear in fuel injection systems. One strategy to utilize DME is to blend it with diesel fuel to obtain cleaner burning fuels that retain satisfactory fuel properties. In the present work, the viscosity of blends of DME and various fuels and additives was characterized, including a federal low-sulfur diesel fuel, soybean oil, biodiesel, and various lubricity additives, over a range of blend ratios. A methodology was developed to utilize a high-pressure capillary viscometer to measure the viscosity of pure DME and blends of DME and other compounds in varying proportions and at pressures up to 3500 psig. While DME is miscible in diesel fuel at any mixture fraction when the blend is held under pressures of 75 psi or above, the viscosity of the blends is below the ASTM diesel fuel specification for even a 25 wt % blend of DME in diesel fuel. None of the additives or fuels provides adequate viscosity when blended with DME unless the blend contains less than 50% DME. Viscosity, rather than lubricity, may be the limiting factor in utilizing DME.
TL;DR: In this paper, the dynamic viscosity and density of two hydrocarbon mixtures representative of some heavy petroleum distillation cuts at 515 K have been studied in the temperature range 293.15-353.15 K and up to 100 MPa.
TL;DR: In this article, the structure and dynamic viscosity of molten metal In in the temperature range from 280 to 750 °C were investigated by using a high-temperature X-ray diffractometer and a torsional oscillation viscometer.
TL;DR: In this article, the experimental uncertainty for the measured viscosities is 2% and the density was measured up to 60 MPa and extrapolated by a Tait-type relationship to 100 MPa.
Abstract: Viscosity and density measurements have been carried out for binary mixtures composed of methylcyclohexane + cis-decalin in the temperature range 293.15 to 353.15 K and at pressures up to 100 MPa. The viscosity was measured with a falling-body viscometer, except at atmospheric pressure where an Ubbelohde viscometer was used. The experimental uncertainty for the measured viscosities is 2%. The density was measured up to 60 MPa and extrapolated by a Tait-type relationship to 100 MPa. For the reported densities the uncertainty is less than 1 kg⋅m−3. An evaluation of the simple mixing laws of Grunberg and Nissan and of Katti and Chaudhri, which require only the density and viscosity of the pure compounds, showed that they can represent the viscosity of the binary mixtures with an average absolute deviation of 2%, corresponding to the experimental uncertainty.
TL;DR: A new family of reverse thermoresponsive alternating [A-B]n block copolymers is introduced, comprising poly(ethylene oxide) (PEO), and poly(propylene oxide)(PPO) chains, using phosgene as the molecule connecting both components, which exhibited clearly superior rheological properties, when compared to existing RTG-displaying PEO–PPO–PEO triblocks.
Abstract: The water solutions of polymers displaying reverse thermal gelation (RTG), such as poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblocks, exhibit a pronounced viscosity increase as temperature rises, within a very narrow temperature interval. Unfortunately, the viscosity increase attained by these solutions is not large enough, resulting in systems displaying limited stability and short residence times. This paper introduces a new family of reverse thermoresponsive alternating [A-B]
n
block copolymers, comprising poly(ethylene oxide) (PEO), and poly(propylene oxide) (PPO) chains, using phosgene as the molecule connecting both components. The effect of various compositional and structural parameters on both the C
i (minimal gelation concentration) and T
i (minimal gelation temperature) of these systems was investigated. The copolymers were characterized by GPC, 1H-NMR, FT-IR, and DSC and the rheological behavior of the water solutions was studied using a Brookfield viscometer. The water systems were also studied by dynamic light scattering (DLS) and fluorescence spectroscopy. The copolymers developed exhibited clearly superior rheological properties, when compared to existing RTG-displaying PEO–PPO–PEO triblocks. For example, while the viscosity of a 15% water solution of the commercially available Pluronic F-127 achieved 5000 Pa.s, at 37 °C, poly(ether carbonate) water solutions (15%) attained viscosities between 25 000 and 150 000 Pa.s.
TL;DR: In this paper, a capillary tube viscometer was designed to measure viscosity of single-phase mixtures at high temperatures and pressures, which can be used in designing solvent stimulation of wells and input to reservoir simulators for heavy oil recovery processes.
TL;DR: In this article, the authors formulated food-grade protein-stabilized emulsions (30vol% vegetable oil, 4wt% sodium caseinate) which exhibit heat-induced gelation at around body temperature.
TL;DR: In this paper, the structure of a high-temperature X-ray diffractometer was determined by using a torsional oscillation viscometer, and it was found that there is an abnormal change in the relationship between the temperature and the viscosity of the alloy.
TL;DR: In this paper, a mass-detecting capillary viscometer (MDCV) was used to measure the rheological characteristics of dairy food continuously over a range of shear rates by single measurement of liquid-mass variation with time.
TL;DR: A robust, prototype instrument for measuring the viscosity of reactive gases used in semiconductor processing generated values of eta that were within +/-0.8% of published reference values throughout the pressure range 0.2-3.2 MPa.
Abstract: We present a detailed acoustic model of the Greenspan acoustic viscometer, a practical instrument for accurately measuring the viscosity η of gases. As conceived by Greenspan, the viscometer is a Helmholtz resonator composed of two chambers coupled by a duct of radius rd. In the lowest order, η=πfρ(rd/Q)2, where f and Q are the frequency and quality factor of the isolated Greenspan mode, and ρ is the gas density. In this level of approximation, the viscosity can be determined by measuring the duct radius and frequency response of the resonator. In the full acoustic model of the resonator, the duct is represented by a T-equivalent circuit, the chambers as lumped impedances, and the effects of the diverging fields at the duct ends by lumped end impedances with inertial and resistive components. The model accounts for contributions to 1/Q from thermal dissipation (primarily localized in the chambers) and from a capillary used for filling and evacuating the resonator. A robust, prototype instrument is being u...
TL;DR: In this article, a comparative study of the LBC model and self-referencing model is presented, showing that the average absolute deviation of the models is between 4.9 and 26.8%, and the maximum deviation is between 11.6 and 49.5%.
Abstract: The dynamic viscosity of toluene and methane mixtures containing 25.03, 37.19, 49.95, 64.11, and 95.00 mol% methane has been measured using a falling-body viscometer. The measurements (280 data points) have been performed in the temperature range 293.15 to 373.15 K and at pressures up to 140 MPa. The data have been discussed in the framework of recent representative models (hard-sphere scheme, friction theory, and free-volume model) as well as with simple mixing laws and empirical models (particularly the LBC model and the self-referencing model) used in the literature. This comparative study shows that the average absolute deviation of the models is between 4.9 and 26.8%, and the maximum deviation is between 11.6 and 49.5%.
Patent•
31 Mar 2003
TL;DR: In this article, an optical distance sensor assembly is used to measure the distance to an arm which is connected to the top of a shaft and then converted to the viscosity of the tested fluid.
Abstract: Viscometer ( 80 ) with a sample cup ( 42 ) rotatable by a pulley ( 26 ) and a timing belt ( 30 ) to shear a tested fluid thus imparting torque to a bob ( 44 ) mounted on a shaft ( 10 ) supported via a frictionless bearing ( 58 ), an optical distance sensor assembly ( 12 ) measures the distance to an arm ( 70 ) which is connected to the top of shaft ( 10 ). This distance information is further converted to the viscosity of the tested fluid.
TL;DR: In this article, the effects of various thermo-mechanical treatments were investigated on the change in viscosity of the semi-solid AZ91D magnesium alloys by using a concentric cylinder type viscometer.
Abstract: Semi-solid processing is an emerging technology for near net-shape production of engineering components. Although there has been significant progress in semi-solid processing of Al alloys, very limited information is available on semi-solid processing of Mg alloys, except for the thixomolding process. In semi-solid casting process, it is necessary to properly control the flow and solidification behavior of semi-solid slurries for high quality products. There are a number of parameters that affect the flow and solidification behavior of semi-solid slurries such as viscosity, casting pressure, shapes of gate and mold cavity, gate velocity, mold temperature, etc. In the present study, the effects of various thermo-mechanical treatments were investigated on the change in viscosity of the semi-solid AZ91D magnesium alloys by using a concentric cylinder type viscometer. The effects of gate velocity and thickness on mold filling behavior of the semi-solid AZ91D alloys were also investigated by using a high-speed camera and the results were compared with those obtained from computer simulations. From these results and microstructure examination, a processing map for high pressure die casting of the semi-solid AZ91D alloy was constructed in order to produce sound castings.
TL;DR: In this article, the effect of temperature on a mixture of polymer and curative in the processing of rocket propellants is reported, and the activation energy of the HTPB-DOA-TDI system was found to be 15.5 kJ/mol.
Abstract: A study of the effect of temperature on a mixture of polymer and curative in the processing of rocket propellants is reported. Experimental viscosity of a hydrox- yl-terminated polybutadiene-toluene diisocyanate (HTPB- TDI) system was measured using a Brookfield viscometer model DV III. Viscosity showed dependence on temperature as well as time. The viscosity data of the HTPB-TDI system showed a linear relationship with temperature, with a change in slope at 45°C. The time dependence model showed a fourth-order curve fit, which gave better results over the exponential model fit. The activation energy re- quired for flow of the HTPB-TDI system was found to be 15.5 kJ/mol. Experimental viscosity measurements at vari- ous temperatures was also carried out on a hydroxyl-termi- nated polybutadiene- dioctyl adipate -toluene diisocyanate (HTPB-DOA-TDI) system. The temperature dependence showed a decrease in viscosity with an increase in temper- ature up to 60 min, beyond which the viscosity increased. Viscosity showed a linear relation with temperature, with a change in the slope at 50°C instead of at 45°C for HTPB-TDI system. Beyond 50°C the data followed a polynomial model similar to that of the HTPB-TDI system, and the results matched well with the experimental data. The activation energy of the HTPB-DOA-TDI system increased with an increase in the binder weight ratio. © 2003 Wiley Periodicals,
TL;DR: In this article, a molecular dynamics simulation was performed to investigate the aggregates of mixing and the interaction between different polymers in aqueous solution, including HPAM, HEC and polyvinylpyrrolidone (PVP).
Abstract: A molecular dynamics simulation was performed to investigate the aggregates of mixing and the interaction between different polymers in aqueous solution. These polymers include partially hydrolyzed polyacryamide (HPAM), hydroxyethylcellulose (HEC) and polyvinylpyrrolidone (PVP). The structures of mixed aggregates were analyzed from the dihedral angle distribution of: (1) pure HPAM; (2) HPAM in aqueous solution; (3) HPAM with small segments of PVP or HEC in aqueous solution. At the same time, the simulated IR spectra and the calculated interaction parameters were used to distinguish the different interactions between HPAM and PVP or HEC. In order to confirm the validity of the simulated predictions, experimental IR spectra of polymer systems were made, and the specific viscosity of the HPAM and PVP or HEC system was measured using capillary viscometry. It can be seen from the viscosity measurements that the viscosity of the HPAM/PVP system in aqueous solution decreases linearly with an increase in concentration of PVP, whereas a maximum viscosity value appears with the increase in concentration of HEC in the HPAM/HEC system. The conclusion was drawn that the interaction between HPAM and HEC is stronger than the one between HPAM and PVP, and that molecular simulation can be considered as an adjunct to experiments and can provide otherwise inaccessible (or, not easily accessible) microscopic information that experimentalists can use.
TL;DR: In this paper, a representative viscosity model has been derived using the friction theory (f-theory) in combination with a BWR type of equation of state (EoS).
TL;DR: In this paper, the authors developed a noninvasive, in-line rheometer using ultrasonics and its comparison with data from a traditional capillary viscometer.
Abstract: This study focuses on the development of a noninvasive, in-line rheometer using ultrasonics and its comparison with data from a traditional capillary viscometer. The ultrasonic based pointwise viscosity measurement technique combines a measurement of the velocity profile and the pressure drop to determine the shear rate and the shear stress distributions, respectively in a pipe. The experiments were carried out using tomato concentrates at 8.75%, 12.75%, and 17.10% total solids content. The flow system consisted of a 53.2 mm diameter acrylic tube, a positive displacement pump and two pressure transducers. Multiple shear viscosity-shear rate data were recorded under actual pipeline conditions from a single combined measurement of the velocity profiles using ultrasonics and the pressure gradient, using the pressure transducers. The samples showed shear thinning behavior and a yield stress. Power law and Casson models were used to fit the data and both obtained R2 values higher than 0.99. The yield stress was also directly determined from the velocity profiles. Shear viscosity versus shear rate data of the 12.75% total solids sample were obtained by capillary rheometry at four different flow rates. These showed very good agreement with those obtained using the velocity profile technique.
TL;DR: In this article, the intrinsic viscosity of polystyrene-block polyisoprene nanofiber fractions in THF was determined using viscometers of different shear rates, suggesting the ready alignment of the nanofibers along the shearing direction.
Abstract: The intrinsic viscosity of five well-characterized polystyrene-block-polyisoprene nanofiber fractions in THF was determined using viscometers of different shear rates. The values increased pronouncedly with decreasing shear rates, suggesting the ready alignment of the nanofibers along the shearing direction. The intrinsic viscosity data of the longer fractions were treated by the Yamakawa−Fujii−Yoshizaki (YFY) theory for wormlike chains to yield reasonable persistence length and hydrodynamic diameter. The validity of the YFY theory should allow the use of intrinsic viscosity in the future for evaluating the molar mass of block copolymer nanofibers.
TL;DR: In this article, the authors considered the effect of fixed plates symmetrically located above and below the oscillating disk viscometer and found that fixed plates can dramatically increase the independence of the damping and period working equations.
Abstract: The period and damping of the free motion of a body oscillating in a fluid depend on the fluid's viscosity and density Commonly, a working equation which expresses the damping as a function of the viscosity and density is solved for the viscosity, the damping being measured and the density being treated as an independently supplied parameter Another working equation exists for the period, and, in general, the period depends on a combination of the viscosity and the density which is linearly independent of the combination that appears in the damping equation It is, therefore, in principle, possible to determine both the viscosity and the density by a simultaneous solution of the two coupled working equations, since the period also is measured In this paper, the working equations that describe the oscillating-disk viscometer are reviewed and their simultaneous solution is considered The effect of fixed plates symmetrically located above and below the oscillating disk is of specific interest The paper's main result is that fixed plates can dramatically increase the independence of the damping and period working equations, so that it becomes indeed feasible to determine the viscosity and the density of a fluid simultaneously from the damping and period of oscillating motion A price is paid, however, because the instrument's working equations when plates are present have multiple solutions Under special conditions, these multiple solutions can coalesce, and then one can only deduce the viscosity from the damping equation if the density is known a priori