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  • Articles  (150)
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  • Springer  (150)
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  • 1
    Electronic Resource
    Electronic Resource
    The yield stress myth? (1985)
    Springer
    Rheologica acta 24 (1985), S. 323-326 
    Details
    ISSN: 1435-1528
    Keywords: Yield stress ; viscosity ; Cross model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract New experimental data obtained from constant stress rheometers are used to show that the yield stress concept is an idealization, and that, given accurate measurements, no yield stress exists. The simple Cross model is shown to be a useful empiricism for many non-Newtonian fluids, including those which have hitherto been thought to possess a yield stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01333960
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  • 2
    Electronic Resource
    Electronic Resource
    Solidification behavior of the theta system 2-propanol/poly(n-butyl methacrylate) (1995)
    Springer
    Rheologica acta 34 (1995), S. 172-181 
    Details
    ISSN: 1435-1528
    Keywords: Thermoreversible gelation ; glass transition ; viscosity ; storage modulus ; loss modulus ; activation energies of flow ; entanglement molecular weights ; poly(n-butyl methacrylate) ; 2-propanol ; concentration and temperature influences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Thermoreversible gelation of the system 2-propanol/poly (n-butyl methacrylate) — as detected by D'SC or dielectric experiments — does not manifest itself in a straightforward manner in the dynamic-mechanical properties. Its occurrence can, however, be seen in many ways: i) For constant composition of the system and a reference temperature lower than T gel, the storage modulus G′ is larger than the loss modulus G″ in the glass transition zone of the master curve and both vary in an almost parallel manner with the angular frequency ω over almost two decades (whereas this feature is normally found for other gelling systems within the rubber plateau or the flow region). ii) The entanglement molecular weight obtained from G″max is markedly less max than the entanglement molecular weight in the melt divided by ϕ2, the volume fraction of the polymer. iii) The temperature influences change from WLF like to Arrhenius-like behavior as T is lowered in the case of highly concentrated polymer solutions; analogous considerations hold true as ϕ2 is increased at constant T. iv) For sufficiently low temperatures, the activation energy of flow exhibits a maximum in the concentration range where the gelation is — according to DSC experiments — most pronounced. Like with ordinary non-gelling systems it is possible to construct master curves. On the basis of Graessley's theory identical dependencies are obtained for the variation of the entanglement parts of the stationary viscosity with shear rate and for the dependence of the entanglement part of the complex viscosity on the frequency ω of oscillation. Zero shear viscosity and limiting value of the complex viscosity for vanishing ω as a function of ϕ2 match smoothly and exhibit two points of inflection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398437
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  • 3
    Electronic Resource
    Electronic Resource
    The relaxation of concentrated polymer solutions (1996)
    Springer
    Rheologica acta 35 (1996), S. 168-185 
    Details
    ISSN: 1435-1528
    Keywords: Polymer solution ; relaxation ; viscosity ; scaling ; polystyrene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The focus of this paper is on the viscoelastic properties of concentrated polymer solutions and polymer melts. Dynamic mechanical measurements were performed on various polystyrene/ethylbenzene solutions with polymer concentrations ranging from 40% up to 100% and temperatures from Tg+30°C up to 70°C (230°C for polymer melts). The basis polymers are two commerical grade polystyrenes (BASF) with M W = 247 kg/mol and 374 kg/mol, respectively. To avoid solvent loss due to evaporating during the measurements, a special sealing technique was used. A phenomenological model which describes quantitatively the relaxation spectrum of concentrated polymer solutions from the flow regime up to the glass transition regime is developed. The relaxation data of the respective polymer melt and the glass transition temperature of the solution are the only input parameters needed. The temperature dependence is described by a universal, concentration invariant WLF-equation. The relaxation spectra are divided into two parts accounting for the entanglement and the segmental relaxation modes, respectively. The relaxation strength related to the flow and entanglement regime scale with c 2.3, whereas the segmental relaxation strength does not alter with concentration. All relaxation times change with concentration proportional to c 3.5. Flow curves can be calculated from these relaxation spectra and thus, our results are useful for engineering applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396044
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  • 4
    Electronic Resource
    Electronic Resource
    A collisional approach to the calculation of time correlation functions. Transport coefficients of gases (1975)
    Springer
    Journal of statistical physics 13 (1975), S. 283-300 
    Details
    ISSN: 1572-9613
    Keywords: Diffusion ; gases ; kinetic theory ; Sutherland-Wassiljewa relations ; thermal conductivity ; time correlation functions ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method of successive approximations is proposed for the evaluation of the time-correlation functions such as those that give the thermal transport coefficients of gases. The method is based on a calculation of the changes in correlations of appropriate functions of the molecular velocity which are a result of collisions in the gas. The decaying rates of the correlations are expressed as integrals of the differential collision cross section. When the first approximation is introduced in the expressions for thermal transport coefficients, results are obtained for the coefficient of binary diffusion and the viscosity and thermal conductivity of single-component systems which are identical with those of the first Chapman-Enskog solutions of the Boltzmann and Enskog equations. For the coefficients of viscosity and thermal conductivity in multicomponent systems, it is shown that the first approximation leads to expressions of the form of the Sutherland and Wassiljewa relations, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01012008
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  • 5
    Electronic Resource
    Electronic Resource
    Negative-viscosity lattice gases (1989)
    Springer
    Journal of statistical physics 56 (1989), S. 517-524 
    Details
    ISSN: 1572-9613
    Keywords: Lattice gases ; cellular automata ; viscosity ; turbulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new irreversible collision rule is introduced for lattice-gas automata. The rule maximizes the flux of momentum in the direction of the local momentum gradient, yielding a negative shear viscosity. Numerical results in 2D show that the negative viscosity leads to the spontaneous ordering of the velocity field, with vorticity resolvable down to one lattice-link length. The new rule may be used in conjunction with previously proposed collision rules to yield a positive shear viscosity lower than the previous rules provide. In particular, Poiseuille flow tests demonstrate a decrease in viscosity by more than a factor of 2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01044449
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  • 6
    Electronic Resource
    Electronic Resource
    Discrete hydrodynamics: Numerical results for the soft-sphere viscosity (1979)
    Springer
    Journal of statistical physics 20 (1979), S. 641-655 
    Details
    ISSN: 1572-9613
    Keywords: Molecular dynamics ; transport coefficients ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Numerical calculations have been done of the viscosity of the soft-sphere liquid, using a new molecular dynamics technique. It is based on a formulation of hydrodynamics which is discrete in space and time, and exactly renormalizable. The present data turn out to be sufficient to estimate the viscosity, but determination of the full equations of motion (and therefore renormalization) requires further calculations using a smaller discrete time interval; these are presently under way. The present results indicate that this method is more than 100 times more efficient than previous (Green-Kubo or nonequilibrium molecular dynamics) methods. This suggests that the discrete formulation is the most natural way to approach hydrodynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01009515
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  • 7
    Electronic Resource
    Electronic Resource
    Lorentz gas shear viscosity via nonequilibrium molecular dynamics and Boltzmann's equation (1985)
    Springer
    Journal of statistical physics 38 (1985), S. 973-988 
    Details
    ISSN: 1572-9613
    Keywords: Boltzmann equation ; nonequilibrium ; viscosity ; molecular dynamics ; irreversibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract When nonequilibrium molecular dynamics is used to impose isothermal shear on a two-body periodic system of hard disks or spheres, the equations of motion reduce to those describing a Lorentz gas under shear. In this shearing Lorentz gas a single particle moves, isothermally, through a spatially periodic shearing crystal of infinitely massive scatterers. The curvilinear trajectories are calculated analytically and used to measure the dilute Lorentz gas viscosity at several strain rates. Simulations and solutions of Boltzmann's equation exhibit shear thinning resembling that found inN-body nonequilibrium simulations. For the three-dimensional Lorentz gas we obtained an exact expression for the viscosity which is valid at all strain rates. In two dimensions this is not possible due to the anisotropy of the scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01010425
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  • 8
    Electronic Resource
    Electronic Resource
    Theoretical Demonstration of a Newly Designed Micro-Rotator Driven by Optical Pressure on a Light Incident Surface (1997)
    Springer
    Optical review 4 (1997), S. 447-449 
    Details
    ISSN: 1349-9432
    Keywords: optical micro-rotator ; cylindrical rotator ; optical torque ; optical tweezers ; ray-tracing ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A newly designed cylindrical optical micro-rotator which has slopes for trapping and rotation on its upper surface is proposed. The cylindrical shape is effective in decreasing viscous drag force (damping factor) in the medium. A ray-tracing method considering the beam waist is employed to analyze the radiation pressure exerted on the upper surface of the rotator. We have demonstrated optical trapping and high speed rotation for various optical beam parameters such as the lens numerical aperture and the Gaussian mode profile as well as rotator shape parameters including oblique angle, height and diameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10043-997-0447-9
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  • 9
    Electronic Resource
    Electronic Resource
    The superstructure of chromatin and its condensation mechanism (1987)
    Springer
    European biophysics journal 14 (1987), S. 307-319 
    Details
    ISSN: 1432-1017
    Keywords: Chromatin ; synchrotron radiation ; ultracentrifugation ; viscosity ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Solutions of rat liver and chicken erythrocyte chromatin at different ionic strngths were characterized by synchrotron X-ray solution scattering, ultracentrifugation, density and viscosity measurements. Previous observations on nuclei were extended to rat liver, calf thymus and yeast nuclei. It is shown that with monovalent cations condensation is independent of the nature of the cation whereas with divalent cations there are significant differences related to the preference of base binding over phosphate binding. The consistency of hydrodynamic and scattering results confirm the view that chromatin in solution at low ionic strength has a helix-like superstructure. A survey of X-ray and neutron scattering results in the literature shows that previous interpretations, e.g. in terms of a 10 nm filament, are incompatible with the experimental data at low resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254896
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  • 10
    Electronic Resource
    Electronic Resource
    Order and fluidity of lipid membranes as determined by fluorescence anisotropy decay (1987)
    Springer
    European biophysics journal 15 (1987), S. 87-102 
    Details
    ISSN: 1432-1017
    Keywords: Lipid bilayers ; fluorescence probes ; order parameters ; diffusion coefficients ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The fluorescence anisotropy decay of four different probes in bilayers of dimyristoylphosphatidylcholine was measured. The probes are diphenylhexatriene, diphenyloctatetraene, trimethylaminodiphenylhexatriene, and trans-parinaric acid. The data for each probe were analyzed in terms of two orientational order parameters, the ordinary order parameter and a higher one, and two rotational diffusion coefficients. The order parameters are largely independent of probe size, but depend on the position of the probes along the membrane normal, thus reflecting the profile of lipid order. If a probe is located in the plateau region of lipid order, its order parameters are interpreted as representing the rigid-body order of lipids. According to this interpretation, the total lipid order in the plateau region originates about equally from rigid-body order and conformational order. The two order parameters obtained for each probe are used to derive approximate angular distributions of the probe molecules. The diffusion coefficient for rotation about the long molecular axis is found to be infinitely large, indicating unhindered rotation about this axis. The diffusion coefficient for rotation about the short molecular axes is evaluated for a viscosity which results as 0.2 poise. This viscosity for rotational diffusion is an order of magnitude smaller than the viscosity for lateral diffusion indicating that at least two viscosities are required to characterize the fluidity of a lipid membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257502
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  • 11
    Electronic Resource
    Electronic Resource
    Fluorescence Study of the Relaxation Process in Excited Hetarylthiazole Cations (2000)
    Springer
    Journal of fluorescence 10 (2000), S. 161-161 
    Details
    ISSN: 1573-4994
    Keywords: Excited state ; quinolyl ; structural relaxation ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The absorption and fluorescence spectra of five cations protonated at the quinolyl nitrogen atom (IH+−VH+) and one ethylated (IEt+) cation were investigated. For these compounds (except VH+) both an anomalously large fluorescence Stokes shift (up to 238 nm) and a large short-wavelength fluorescence shift (up to 145 nm) at decreasing temperatures (down to 77 K) were observed. This is not the case for unprotonated molecules. The ground-state conjugation between quinolyl and another molecular fragment was found for II, IH+, IIH+, and IEt+. The relaxation process of excited cations is medium viscosity and temperature dependent. The experimental results are explained in terms of excited-state structural relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009447226786
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  • 12
    Electronic Resource
    Electronic Resource
    Energy Deactivation of Electronic Excitation of 2-N-Piperidine-5-(2",2"-Dicyanvinyl)Thiophene Depending on the Solvent Viscosity (2000)
    Springer
    Journal of applied spectroscopy 67 (2000), S. 935-938 
    Details
    ISSN: 1573-8647
    Keywords: fluorescence ; viscosity ; picosecond spectroscopy ; conformer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using the methods of picosecond laser spectroscopy and steady-state luminescence, we investigated the energy, spectral, and kinetic characteristics of 2-N-piperidine-5-(2",2"-dicyanvinyl)thiophene (PDCVTh) in solutions at room temperature. The mechanism of radiationless energy deactivation of electronic excitation in PDCVTh is interpreted in terms of the notions of conformational changes, controlled by medium viscosity, in a molecule after absorption by it of excitation energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004144623480
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  • 13
    Electronic Resource
    Electronic Resource
    Empirical relation between permittivity $$(\varepsilon)$$ and viscosity $$(\eta)$$ of polar and non-polar liquids (1997)
    Springer
    Speculations in science and technology 20 (1997), S. 45-50 
    Details
    ISSN: 1573-9309
    Keywords: permittivity ; viscosity ; interactions.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract An empirical relation is proposed wherein the inverse of the permittivity of a pure liquid is described as a linear function of the inverse of the viscosity. It also provides a simple method of calculating the permittivity of a solid at the freezing temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018508502411
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  • 14
    Electronic Resource
    Electronic Resource
    On-line measurement of elasticity and viscosity in flowing polymeric liquids (1996)
    Springer
    Rheologica acta 35 (1996), S. 110-116 
    Details
    ISSN: 1435-1528
    Keywords: Slit die ; on-line rheometry ; first normal stress difference ; hole pressure ; Stressmeter ; viscosity ; molten polymers ; multigrade oil elasticity ; high shear rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A new slit-die rheometer (the “Stressmeter”) for on-line and sample measurement of the viscosity, η, and the first normal stress difference, N 1, in steady shear flow for molten polymers and other high-viscosity liquids is described. Two liquid-filled transverse slots, located in one die wall near the center station, give pressures P 2 and P 3 from whose difference the wall shear stress σ is calculated. In the other die wall at a location opposite the center of the P 2 slot is a flush-mounted transducer, giving a pressure P 1. N 1 is calculated from the hole pressure P * = P 1−P 2. A metering pump, used to measure the flow rate Q, is supplied with melt either from an extruder (online mode) or from a pressurized sample cylinder (sample mode). The wall shear rate γ is calculated from Q and σ; the Weissenberg-Rabinowitsch correction and a new small-viscous-heating-correction algorithm (affecting σ) are used. Viscous heating corrections are small; entrance and exit errors are negligible. The instrument is tested by comparing its results with those obtained from cone-plate and capillary rheometers. Measurement ranges extend to σ = 200 kPa, γ = 3000 s−1, and temperature = 250°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396037
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  • 15
    Electronic Resource
    Electronic Resource
    Curing effects on viscosity of reactive epoxy resin adhesives (1996)
    Springer
    Rheologica acta 35 (1996), S. 321-328 
    Details
    ISSN: 1435-1528
    Keywords: Epoxy resin ; adhesive ; viscosity ; curing ; chemorheology ; reaction kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The influence of temperature and the extent of curing on the viscosity of a ,reactive epoxy resin adhesive is described and a mathematical model for the behavior is introduced. The temperature dependence of viscosity can be described by the WLF equation. The parameters required for the WLF equation are obtained from experiments in the temperature range where the crosslinking reaction has not yet been initiated. The viscosity and glass transition temperature increase with increasing curing. The glass transition temperature can also be described with an equation of the WLF type. Kinetic experiments on the epoxy resin adhesive enable a time and temperature dependent description of the extent of curing with a series reaction of the type A→B→C, where each partial reaction is of order n. The viscosity model and reaction kinetics enable calculation of the viscosity as a function of time and temperature, which agrees well with the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403532
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  • 16
    Electronic Resource
    Electronic Resource
    Translational diffusion of rubrene and tetracene in polyisobutylene (1997)
    Springer
    Rheologica acta 36 (1997), S. 209-216 
    Details
    ISSN: 1435-1528
    Keywords: Translational diffusion ; probes ; rotation ; viscosity ; local segmental dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The translational diffusion coefficients of rubrene and tetracene in amorphous polyisobutylene (PIB) were measured using the holographic fluorescence recovery after photobleaching technique. Over the temperature range from 400 to 235 K (T g =205 K), tracer diffusion coefficients from 10−7 to 10−14 cm2/s were observed. These diffusion coefficients have essentially the same temperature dependence as the rotational correlation times for these two probes in PIB. Both of these observables have a slightly stronger temperature dependence than does the viscosity. These results contrast strongly with the results of similar experiments on polystyrene and polysulfone. These results are consistent with the hypothesis that local segmental dynamics are more spatially homogeneous in PIB than in polystyrene and polysulfone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366661
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  • 17
    Electronic Resource
    Electronic Resource
    Translational diffusion of rubrene and tetracene in polyisobutylene (1997)
    Springer
    Rheologica acta 36 (1997), S. 209-216 
    Details
    ISSN: 1435-1528
    Keywords: Key words Translational diffusion ; probes ; rotation ; viscosity ; local segmental dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The translational diffusion coefficients of rubrene and tetracene in amorphous polyisobutylene (PIB) were measured using the holographic fluorescence recovery after photobleaching technique. Over the temperature range from 400 to 235K (T g =205K), tracer diffusion coefficients from 10–7 to 10–14cm2/s were observed. These diffusion coefficients have essentially the same temperature dependence as the rotational correlation times for these two probes in PIB. Both of these observables have a slightly stronger temperature dependence than does the viscosity. These results contrast strongly with the results of similar experiments on polystyrene and polysulfone. These results are consistent with the hypothesis that local segmental dynamics are more spatially homogeneous in PIB than in polystyrene and polysulfone.
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    URL: http://dx.doi.org/10.1007/BF00366661
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  • 18
    Electronic Resource
    Electronic Resource
    Polymer contribution to the thermal conductivity and viscosity in a dilute solution (Fraenkel Dumbbell model) (1997)
    Springer
    Rheologica acta 36 (1997), S. 269-276 
    Details
    ISSN: 1435-1528
    Keywords: Key words Transport phenomena ; thermal conduction ; bead-spring models ; polymer solutions ; viscosity ; normal stresses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The phase-space kinetic theory for polymeric liquid mixtures is used to obtain an expression for the polymer contribution to the thermal conductivity of a nonflowing, dilute solution of polymers, where the polymer molecules are modeled as Fraenkel dumbbells. This theory takes into account three mechanisms for the energy transport: diffusion of kinetic energy (including the Öttinger-Petrillo term), diffusion of intramolecular energy, and the work done against the intramolecular forces. This paper is an extension of previous developments for the Hookean dumbbell model and the finitely-extensible dumbbell model. A comparison among the dumbbell results suggests that the thermal conductivity increases with chain stiffness. In addition, the zero-shear-rate viscosity and first normal-stress coefficient are also given for the Fraenkel dumbbell model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366668
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  • 19
    Electronic Resource
    Electronic Resource
    Effective viscosity of porous particle suspensions (1997)
    Springer
    Rheologica acta 36 (1997), S. 483-484 
    Details
    ISSN: 1435-1528
    Keywords: Suspension ; viscosity ; apparent viscosity coefficient ; coal ; oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The attempt of quantitative description of suspension viscosity with regard to concentration of dispersed phase particles as well as particle (porous) — liquid phase interaction has been presented. Calculated apparent viscosity coefficients have been compared with measured viscosities of oil-coal suspension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396333
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  • 20
    Electronic Resource
    Electronic Resource
    Effective viscosity of porous particle suspensions (1997)
    Springer
    Rheologica acta 36 (1997), S. 483-484 
    Details
    ISSN: 1435-1528
    Keywords: Key words Suspension ; viscosity ; apparent viscosity coefficient ; coal ; oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The attempt of quantitative description of suspension viscosity with regard to concentration of dispersed phase particles as well as particle (porous) – liquid phase interaction has been presented. Calculated apparent viscosity coefficients have been compared with measured viscosities of oil-coal suspension.
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    URL: http://dx.doi.org/10.1007/BF00396333
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  • 21
    Electronic Resource
    Electronic Resource
    Viscoplasticity of agglomerated suspensions (1989)
    Springer
    Rheologica acta 28 (1989), S. 311-315 
    Details
    ISSN: 1435-1528
    Keywords: Suspension ; agglomeration ; viscoplasticity ; viscosity ; yield stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract This work is a theoretical study on the effects of agglomeration on the fluidity and plasticity of a suspension of neutrally buoyant particles in a Newtonian fluid. The dynamics of a cluster of permanently attached spherical particles in a simple shear field is analyzed. The viscous and plastic components of the drag force acting on each of the agglomerated particles is then calculated and found to depend on the size of the individual particle unit, its location being relative to the center of the cluster and the material properties of the engulfing fluid. This information in conjunction with the knowledge of the interparticle cohesive forces is used to establish criteria for the agglomerate size reduction during dispersive mixing. From the kinematics of the cluster movement and the forces acting on its particulate components the rate of energy dissipation is calculated and utilized to evaluate the viscosity and yield stress of the suspension. These rheological parameters depend on the volume fraction and architecture of the agglomerate, the number of fused particles per cluster, and the viscosity of the suspending fluid. The analysis is also extended to include the case of polydispersity of agglomerate sizes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01329340
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  • 22
    Electronic Resource
    Electronic Resource
    Shear dependence of viscosity for perfluoropolyether fluids (1986)
    Springer
    Rheologica acta 25 (1986), S. 69-71 
    Details
    ISSN: 1435-1528
    Keywords: Perfluoropolyether ; shear dependence ; viscosity ; Couette high-shear viscometer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The shear dependence of the bulk viscosities of two structurally different types of perfluoropolyether fluids was determined by two different techniques. The first involved direct measurement in a high shear Couette viscometer, the second utilized the time-temperature superposition principle to establish master curves from viscosity determinations at low shear rates and temperature; the results are comparable. Both fluids begin to show non-Newtonian behavior at shear rates above 10,000 s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01369983
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  • 23
    Electronic Resource
    Electronic Resource
    The effect of molecular weight on the rheological properties of poly(dimethylsiloxane) filled with fumed silica (1986)
    Springer
    Rheologica acta 25 (1986), S. 153-160 
    Details
    ISSN: 1435-1528
    Keywords: Filled polymer ; viscosity ; normal stress ; stress growth ; stress relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The viscometric, stress relaxation, and stress growth rheological properties were measured for various molecular weight PDMS fluids filled with fumed silica. The stress growth function exhibited significant overshoot, when the continuous phase molecular weight was slightly greater than the entanglement molecular weight; however, significant overshoot peaks were not observed, when the continuous phase molecular weight was less than or much greater than the molecular weight between entanglements. The experimentally observed transient rheological properties are rationalized in terms of a molecular model, where interparticle interactions occur via entanglements of the polymer adsorbed on the silica surface. When the molecular weight of the adsorbed polymer is greater than the entanglement molecular weight, the strength of the interparticle interaction will increase substantially and the particle diffusivity will substantially decrease.
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    URL: http://dx.doi.org/10.1007/BF01332133
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    Steady shear viscosity of short fibre suspensions in thermoplastics (1998)
    Springer
    Rheologica acta 37 (1998), S. 289-298 
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    ISSN: 1435-1528
    Keywords: Key words Reinforced ; thermoplastics ; viscosity ; convergent channel ; shear-thinning ; fibre suspension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The rheological behaviour of a polyethylene, two polyamides and a silicone oil filled with different fibre contents are studied in capillary rheometry. The viscosity increase induced by the fibres is important for the silicone oil, and negligible for the polyethylene. The polyamide is intermediate. The same classification stands for the pressure loss in the convergent channel upstream from the capillary. A constitutive equation based on a cell model which takes into account the shear-thinning behaviour of the matrix is built. The predictions of the model are in correct agreement with the measurements.
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    URL: http://dx.doi.org/10.1007/s003970050116
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    An AFVS model for polymer solutions: New scaling relationship (1985)
    Springer
    Rheologica acta 24 (1985), S. 341-356 
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    ISSN: 1435-1528
    Keywords: Polymer solution ; viscosity ; free volume state ; concentration-molecular weight superposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The altered free volume state (AFVS) approach developed by Kulkarni and Mashelkar has been extended to develop a model for the viscosity of polymer solutions. The effect of polymer concentration, molecular weight and electrolyte concentration is shown to be satisfactorily explained in the framework of AFVS model. The regimes of viscosity behaviour have been defined for the systems investigated and the transitions involved identified. The approach leads to the identification of a surprisingly simple and unique scaling parameterΦ P, which enables excellent concentration-molecular weight superposition.
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    URL: http://dx.doi.org/10.1007/BF01333963
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    Ultrasonic devulcanization of waste rubbers: Experimentation and modeling (1996)
    Springer
    Rheologica acta 35 (1996), S. 616-630 
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    ISSN: 1435-1528
    Keywords: Rubber ; devulcanization ; revulcanization ; ultrasound ; cavitation ; viscosity ; model ; experiment ; mechanical properties ; gel fraction ; crosslink density ; pressure drop ; converging flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Continuous ultrasonic devulcanization of ground tire rubber (GRT) and styrene-butadiene rubber (SBR) is considered. Experiments are performed under various processing conditions. Two recipes of SBR with different amounts of polysulfidic linkages are utilized. Gel fraction and crosslink density of devulcanized rubbers are measured and a unique relationship between them is established. Die characteristics with and without imposition of ultrasonic waves are determined. Devulcanized samples are revulcanized and mechanical properties are measured. In some cases, properties of revulcanized SBR samples exceeded those of virgin vulcanizates. This is explained based on the presence of a double network in the revulcanized rubber. A modification of acoustic cavitation and flow modeling of ultrasonic devulcanization of SBR and GRT is proposed using a concept of effective viscosity characterizing the flow of vulcanized particles before devulcanization combined with a shear rate, temperature and gel fraction-dependent viscosity of devulcanized rubber. Velocity, shear rate, pressure, and temperature field along with gel fraction, crosslink density and number of bonds broken are simulated. Predicted data on gel fraction, crosslink density, and pressure using the present modification of the model are found to be closer to experimental data then previously reported.
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    URL: http://dx.doi.org/10.1007/BF00396511
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    Semi-empirical theory of the viscosity of moderately dilute polymer solutions (1986)
    Springer
    Rheologica acta 25 (1986), S. 487-493 
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    ISSN: 1435-1528
    Keywords: Semidilute polymer solution ; viscosity ; molecular-weight dependence ; theta temperature ; polystyrene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The viscosityη of moderately dilute polymer solutions is formulated on the postulates that in this concentration regionη is governed by the domain volume per polymer segment and the “noddle effect” due to entangling chains. The former is treated semi-molecular theoretically, and the latter entirely phenomenologically. All the parameters involved in the theory can be estimated from appropriate dilute solution data as well as the asymptotic molecular-weight dependence ofη at different concentrations. It is shown that the theory describes almost quantitatively the experimental data obtained by Hamada and Adam and Delsanti for polystyrene in benzene and cyclohexane. Part of these data reveals the breakdown of the semidilute solution approximation used in the theory.
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    URL: http://dx.doi.org/10.1007/BF01774398
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    Surfactant systems for drag reduction: Physico-chemical properties and rheological behaviour (1986)
    Springer
    Rheologica acta 25 (1986), S. 468-486 
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    ISSN: 1435-1528
    Keywords: Surfactant ; solution ; micelle ; viscoelasticity ; viscosity ; drag reduction
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The first part of the work presents an overview of the physical chemistry of surfactants which in aqueous solutions reduce the frictional loss in turbulent pipe flow. It is shown that these surfactants form rodlike micelles above a characteristic concentraionc t. The experimental evidence for rodlike micelles are reviewed and the prerequisites that the surfactant system must fulfill in order to form rodlike micelles are given. It is demonstrated by electrical conductivity measurements that the critical concentration for the formation of spherical micelles shows little temperature dependence, whereasc t increases very rapidly with temperature. The length of the rodlike micelles, as determined by electric birefringence, decreases with rising temperature and increases with rising surfactant concentration. The dynamic processes in these micellar systems at rest and the influence of additives such as electrolytes and short chain alcohols are discussed. In the second part, the rheological behaviour of these surfactant solutions under laminar and turbulent flow conditions are investigated. Viscosity measurements in laminar pipe and Couette flow show the build-up of a shear induced viscoelastic state, SIS, from normal Newtonian fluid flow. A complete alignment of the rodlike micelles in the flow direction in the SIS was verified by flow birefringence. In turbulent pipe flow, drag reduction occurs in these surfactant systems as soon as rodlike micelles are present in the solution. The extent and type of drag reduction, i.e. the shape of the friction factor versus Reynolds number curve, depends directly on the size, number and surface charge of the rodlike micelles. The friction factor curve of each surfactant investigated changes in the same characteristic way as a function of temperature. For each surfactant, independent of concentration, an upper absolute temperature limit,T L, for drag reduction exists which is caused by the micellar dynamics.T L is influenced by the hydrophobic chain length and the counter-ion of the surfactant system. A first attempt is made to explain the drag reduction of surfactants by combining the results of these rheological measurements with the physico-chemical properties of the micellar systems.
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    Rheology and processing of salad dressing emulsions (1995)
    Springer
    Rheologica acta 34 (1995), S. 513-524 
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    ISSN: 1435-1528
    Keywords: Droplet size ; emulsion ; linear viscoelasticity ; mayonnaise ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract In order to study the influence that the processing parameters exert on the rheology and stability of salad dressing emulsions, both steady-state shear and oscillatory measurements, as well as droplet size distribution tests were performed. Emulsions containing a mixture of egg yolk and sucrose stearate as emulsifier were prepared using two different emulsification machines, a rotor-stator turbine and a colloidal mill. An increase both in energy input and in the temperature of processing yields higher values of the steady-state viscosity, an increase in emulsion stability and, generally, lower droplet size and lower polydispersity. Furthermore, a plateau region in the loss modulus versus frequency plots appears as the energy input and processing temperature increase. This effect has been analyzed by calculating the relaxation spectra of these emulsions. The results have been discussed taking into account the relationship between several structural parameters, such as interparticle interactions and droplet size distribution, and the rheological response of these emulsions.
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    Polymer contribution to the thermal conductivity and viscosity in a dilute solution (Fraenkel Dumbbell model) (1997)
    Springer
    Rheologica acta 36 (1997), S. 269-276 
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    ISSN: 1435-1528
    Keywords: Transport phenomena ; thermal conduction ; bead-spring models ; polymer solutions ; viscosity ; normal stresses
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The phase-space kinetic theory for polymeric liquid mixtures is used to obtain an expression for the polymer contribution to the thermal conductivity of a nonflowing, dilute solution of polymers, where the polymer molecules are modeled as Fraenkel dumbbells. This theory takes into account three mechanisms for the energy transport: diffusion of kinetic energy (including the Öttinger-Petrillo term), diffusion of intramolecular energy, and the work done against the intramolecular forces. This paper is an extension of previous developments for the Hookean dumbbell model and the finitely-extensible dumbbell model. A comparison among the dumbbell results suggests that the thermal conductivity increases with chain stiffness. In addition, the zero-shear-rate viscosity and first normal-stress coefficient are also given for the Fraenkel dumbbell model.
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    Discrete hydrodynamics: Determination of equations of motion by simulation (1979)
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    Journal of statistical physics 20 (1979), S. 629-639 
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    ISSN: 1572-9613
    Keywords: Molecular dynamics ; transport coefficients ; viscosity
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    Topics: Physics
    Notes: Abstract A detailed procedure is described for computing discrete equations of motion for a fluid, to implement a new method which turns out to be substantially more efficient than previous methods for calculating transport coefficients. This paper describes the calculations of discrete averages from molecular dynamics data and the numerical extraction of the equation-of-motion coefficients in a way which makes maximum use of the geometric symmetry of the problem. Extrapolation to the infinite-system limit and eventual computation of transport coefficients by renormalization are discussed. The method described in detail here is briefly sketched and applied numerically to computing the viscosity of the soft-sphere liquid in a subsequent paper.
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    Shear flow in the two-body Boltzmann gas. II. Small and large γ expansion of the shear viscosity (1986)
    Springer
    Journal of statistical physics 44 (1986), S. 107-128 
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    ISSN: 1572-9613
    Keywords: Boltzmann equation ; nonequilibrium ; viscosity ; molecular dynamics
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    Topics: Physics
    Notes: Abstract In two and three dimensions, the relaxation time Boltzmann equation can be solved analytically for the distribution function for a system of two hard particles subject to isothermal shear. The previous solutions of Morriss, and Ladd and Hoover are shown to be formally equivalent. The integral representation for the average of each of the elements of the pressure tensor in the steady state is obtained for both sllod and dolls tensor equations of motion. Rigorous equations are derived which relate the viscosity and the normal stress differences in these two methods. We obtain asymptotic expansions for each element of the pressure tensor for both small and largeγ. For high shear rates, the viscosity is found to vanish as γ−2 logγ in both two and three dimensions.
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    Decay of angular correlations in hard-sphere fluids (1989)
    Springer
    Journal of statistical physics 57 (1989), S. 473-482 
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    ISSN: 1572-9613
    Keywords: Angular correlations ; hard spheres ; long-time tails ; stretched exponential ; viscosity
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    Topics: Physics
    Notes: Abstract The decay of the collisional contribution to the shear-stress autocorrelation function is shown to be inconsistent with at −3/2 inverse-power law. The decay of the self part (a combination of pair and triplet correlations) indicates a stretched-exponential decay with a density-independent exponent. The pair contribution by itself also shows stretched-exponential behavior in both two and three dimensions, with different, but still density-independent, exponents. At very long times this stretched-exponential decay of the pair correlations switches over to an algebraic decay, consistent with the diffusional separation of pairs of particles.
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    The prediction of the viscosity of dense gas mixtures (1989)
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    International journal of thermophysics 10 (1989), S. 125-132 
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    ISSN: 1572-9567
    Keywords: high density ; mixtures (gas) ; prediction ; viscosity
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    Topics: Physics
    Notes: Abstract An extension of an earlier procedure for the evaluation of the viscosity of very dense gas mixtures is proposed. The scheme is based upon the rigid-sphere theory of dense fluids, which is modified to take into account the behavior of real gases in a self-consistent manner. In particular, it is shown that a pseudoradial distribution function for each pure gas constructed from pure component viscosity data is a smooth function of density and is well behaved in limits of both high and low density. The method proposed removes the restrictions on the range of applicability of earlier methods. Comparisons with the limited amount of experimental information available indicate that the procedure allows evaluation of the viscosity of gas mixtures to within a few percent.
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    Viscosity of liquid lithium by an oscillating-cup viscometer in the temperature range 464–923 K (1989)
    Springer
    International journal of thermophysics 10 (1989), S. 173-182 
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    ISSN: 1572-9567
    Keywords: high temperature ; liquid metal ; lithium ; oscillation viscometer ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The liquid lithium has been proposed as a blanket substance of a D-T fusion reactor. Among the previously published viscosity data of liquid lithium by different authors, a sizable discrepancy is observed. In the present study, the viscosity of liquid lithium was measured by an oscillating-cup viscometer in the temperature range from 464 to 923 K. It was concluded that the disagreement among the previous studies was owing to the difference of the theory used for calculating the viscosity and also to the influence of the corrosion of the container wall. It was shown that recalculation of values in previous studies with the aid of Kestin-Newell equation, the equation used in the present study, would show reasonable agreement with the present results. The accuracy of the present measurements was estimated as ±3%.
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    Spinodal decomposition and nucleation in the presence of flow (1989)
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    International journal of thermophysics 10 (1989), S. 293-308 
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    ISSN: 1572-9567
    Keywords: fluid binary mixtures ; light scattering ; nucleation ; shear flow ; spinodal decomposition ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spinodal decomposition and nucleation of critical fluids are discussed in the presence of laminar shear and turbulence on the basis of recent experiments. In such situations we can realize stationary emulsion-like domain structures due to dynamical balance between thermodynamic instability and shear-induced deformations. In the spinodal decomposition case, unique is the strong shear regime in which the shear exceeds the average relaxation rate of the order parameter. In the nucleation case shear can enhance aggregation of droplets, thus speeding up the growth. But if the shear exceeds a relatively small critical value, even critical droplets can be broken, then leading to complete suppression of the droplet formation. We also predict a considerable increase of the effective viscosity and a large non-Newtonian effect due to domains in the course of spinodal decomposition.
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    Viscosity of refrigerants R12, R113, and R114 and mixtures of R12 + R114 at high pressure (1989)
    Springer
    International journal of thermophysics 10 (1989), S. 701-712 
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    ISSN: 1572-9567
    Keywords: gaseous mixtures ; R12 + R114 ; refrigerants ; R12 ; R113 ; R114 ; superheated and supercritical ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New viscosity measurements for the gaseous and supercritical state of the halogenated hydrocarbons R12, R113, and R114 and binary mixtures of R12 + R114 of different compositions are presented. The measurements were carried out at superheated and supercritical temperatures from 30 to 200° C and in the pressure range from 1 to 80 bar. Viscosity was measured with an oscillating-disk viscometer and the data obtained are relative to the viscosity of nitrogen. The estimated accuracy of the measured results is ±0.6%. The results obtained show that, at subcritical temperatures, the pressure effect on viscosity is negative. This anomalous behaviour is investigated in detail in this work. At atmospheric pressure the viscosity of gas mixtures is almost a linear function of their composition. At high pressure, the residual viscosities η -η 0 of both the pure components and the mixtures were used to follow a single relationship versus the residual reduced density ρ r0.
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    Status of the round robin on the transport properties of R134a (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 63-78 
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    ISSN: 1572-9567
    Keywords: R134a ; dilute gas ; refrigerant ; saturation properties ; 1,1,1,2-tetrafluoroethane ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper contains a status report on an international project coordinated by the Subcommittee on Transport Properties of Commission 1.2 of the International Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of R134a. The project has involved the remeasurement of the transport properties of a single sample of R134a in nine laboratories throughout the world in order to test the hypothesis that at least part of the discrepancy could be attributed to the purity of the sample. This paper provides an intercomparison of the new experimental results obtained to data in this project for the viscosity and the thermal conductivity in both gaseous and liquid phases. The agreement between the viscosity data from the laboratories contributing to the project was improved with several techniques, now producing consistent results. This suggests that the purity of the samples of R134a used in previous work was at least partly reponsible for the discrepancies observed. For the thermal conductivity in the liquid phase the results of the measurements are also more consistent than before, although not for all experimental techniques. Not all of the previous measurements suffered from significant sample impurities, so the present measurements on a consistent high-purity sample can he used to detect data sets which are outhers, possibly because of impurities. Identification of laboratories and techniques with systematic differences may require the examination of data for several fluids. The implications for future measurements of the transport properties of other refrigerants are significant.
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    Measurements of the viscosity of new refrigerants in the temperature range 270–340 K at pressures up to 20 MPa (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 133-143 
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    ISSN: 1572-9567
    Keywords: high pressure ; refrigerants ; vibrating wire ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A recently modified vibrating-wire instrument was employed to measure the liquid viscosity of a wide selection of new refrigerants under pressure. Calibration of the viscometer with water over the range of measurements confirmed that the estimated uncertainty of the measurements is 0.5%, while the precision is 0.3%. With this instrument, the viscosity of chlorofuorocarbons (CFC's) and alternative refrigerants. R11. R12. R22, R32. R124, R125. 11134a. R 141 b, and R152a, was measured over the temperature range from 270 to 340 K, from just above the saturation pressure up to 211 M Pa. The experimental data, represented by polynomial functions of temperature and pressure, are used in a comparative examination of other recently reported experimental measurements of the viscosity of all these refrigerants. to investigate the uncertainty with which the viscosity is known.
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    Critical dynamics of a sheared micellar solution (1995)
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    International journal of thermophysics 16 (1995), S. 355-361 
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    ISSN: 1572-9567
    Keywords: critical dynamics ; micellar solution ; shear effects ; spinodal decomposition ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated the dynamic behavior of a nonionic micellar solution of tetra-ethylene glycoln-decylether (C10 E4) in water near its critical point in the presence of shear. The non-Newtonian behavior of the viscosityν can be represented byν ν* = [ 1 +a(Sτ4)=]ω2, whereν* is the viscosity in the absence of shear,S is the shear rate. τ4 is the lifetime of the critical Iluctuations,a is a system-dependent constant, and ω = 0.02 In addition, we have found that, before attaining a steady state, the sheared mixture undergoing phase separation shows significant shear-dependent rheological effects due to the presence of concentration domains.
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    The Viscosity of Toluene in the Temperature Range from 210 to 370 K at Pressures up to 30 MPa (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1367-1377 
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    ISSN: 1572-9567
    Keywords: toluene ; vibrating-wire technique ; viscosity
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    Topics: Physics
    Notes: Abstract The paper presents new measurements of the viscosity of toluene over a temperature range from 210 to 370 K, from the saturation line up to pressures of 30 MPa. The measurements were performed with a vibrating-wire viscometer. The uncertainty of the measurements, confirmed above room temperature with the measurement of the viscosity of water, is estimated to be ±0.5%.
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    URL: http://dx.doi.org/10.1023/A:1021428819290
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    Validation of an accurate vibrating-wire densimeter: Density and viscosity of liquids over wide ranges of temperature and pressure (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 781-802 
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    ISSN: 1572-9567
    Keywords: cyclohexane ; density ; liquid ; pVT ; 1,1,1,2-tetrafluoroethanc (R134a) ; 2.2.4-trimelthylpentane ; vibrating-wire densimeter ; viscosity
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract A new vibrating-wire instrument for the meaasurement of the density of fluids at high pressures was described in a previous paper. The technique makes use of the buoyancy force on a solid sinker and detect, this force with a vibrating wire placed inside the measuring cell. Owing to the simple geometry of the oscillating element there exists a complete theoretical description of its resonance characteristics. enabling the calculation of the density of the fluid from their measurement. In the present paper a new method for the determination of the cell constants is outlined which permits the operation of the densimeter essentially as an absolute instrument. Furthermore. it is shown that the viscosity ol the fluid can be measured Simultaneously with the density. New results for three fluids are presented: for cyclohexane at temperatures from 298 to 348 K and pressures up to 40 MPa. for 2,2,4-trimethylpentane between 197 and 348 K at 0.1 MPa, and for 1,1,1,2-tetrafluoroethane from 197 to 298 K close to saturation. The sets of measurements where chosen with the intention of testing the performance of the apparatus. complementing previous work at higher pressures. The densities and viscosities measured exhibit the same accuracy for all of the three fluids over the entire temperature and pressure ranges and were obtained using the same set of cell parameters The precision of the densities is ±0.03% and their estimated accuracy is ±0.05%. File viscosities have a precision of ±0.6%, and an estimated accuracy of ±2%.
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    Revised Viscosities of Saturated Liquid Halocarbon Refrigerants from 273 to 353 K (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 909-912 
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    ISSN: 1572-9567
    Keywords: halocarbons ; refrigerants ; saturated liquid ; vapor buoyancy effect ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper presents revised saturated liquid viscosities for 15 halocarbon refrigerants, that is, R11, R12, R22, R13B1, R152a, R113, R123, R123a, R143a, R114, R134a, R141b, R142b, R225ca, and R225cb, reported in our previous papers [1, 2], in which the vapor buoyancy correction for the sealed capillary viscometer was not applied. The maximum corrections amount to from 1.2% for R225cb to 17.4% for R143a. The erroneous data in our previous papers should be considered obsolete except for the low-vapor density refrigerants R11, R123, R123a, R113, R141b, R225ca, and R225cb, for which the maximum correction is 2.4%.
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    The viscosities and densities of selected organic compounds and mixtures of interest in coal liquefaction studies (1986)
    Springer
    International journal of thermophysics 7 (1986), S. 599-608 
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    ISSN: 1572-9567
    Keywords: corresponding states ; decalin ; density ; m-cresol ; m-xylene ; 1-methylnaphthalene ; quinoline ; tetrahydrofuran ; tetralin ; thiophene ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental measurements are presented for the density and viscosity of selected organic compounds and mixtures at ambient pressure (0.083 MPa) and at temperatures of 298, 318, 338, and 358 K. The compounds studied were decalin, 1-methylnaphthalene, tetralin, m-xylene, tetrahydrofuran, thiophene, quinoline 2,6-lutidine, and m-cresol. Measurements were also made on three mixtures of the compounds decalin, 1-methylnaphthalene, tetralin, m-xylene, and m-cresol. The experimental results are compared with predictions made using a modified corresponding states procedure called TRAPP. The density predictions for the individual compounds and mixtures are good in all cases. For the viscosity, however, the predictions are in reasonable agreement with experiment only for nonassociating compounds and mixtures at reduced densities less than 3. These results suggest that TRAPP may prove very useful as a screening test to distinguish between nonassociating and highly associating mixtures. Such a test would be extremely useful when dealing with mixtures of unknown composition, such as coal liquids.
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    URL: http://dx.doi.org/10.1007/BF00502393
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    The transport coefficients of polyatomic liquids (1986)
    Springer
    International journal of thermophysics 7 (1986), S. 273-284 
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    ISSN: 1572-9567
    Keywords: alkanes ; hard-sphere theory ; hydrocarbons ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper presents the results of a preliminary attempt to represent both the viscosity and the thermal conductivity of normal alkanes in the liquid phase by means of a mutually consistent scheme. The correlation method proposed is based upon the general results of the hard-sphere theory of dense fluids, although it does not make use of the detailed predictions of that model. It is shown that the viscosity of the alkanes, ethane, propane, n-butane, n-hexane, and n-octane may be represented by a single, universal function of reduced volume if each species is assigned a characteristic molar volume which is but weakly temperature dependent. Using the same values of molar volume the thermal conductivity of the same fluids can be represented by a further universal function of reduced volume by means of the choice of a second, temperatureindependent parameter.
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    URL: http://dx.doi.org/10.1007/BF00500154
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    Prediction of Fluid Mixture Transport Properties by Molecular Dynamics (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 437-448 
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    ISSN: 1572-9567
    Keywords: alkanes ; carbon dioxide ; diffusion ; mixtures ; molecular dynamics ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Equilibrium molecular dynamics simulations of mixtures of n-decane with methane, ethane, and carbon dioxide and of the mixture carbon dioxide–ethane were performed using the anisotropic united atoms model for n-decane and one-and two-center Lennard–Jones models for the light components. The Green–Kubo relations were used to calculate the viscosity, thermal conductivity, and inter- and intradiffusion. Viscosities are predicted with a maximum deviation of 30% at low gas concentrations and less than 10% deviation at high gas concentrations. The viscosity and thermal conductivity are less sensitive to the cross interactions than the diffusion coefficients, which exhibit deviations between models and with experiments of up to 60%.
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    URL: http://dx.doi.org/10.1023/A:1022513411043
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    Nonequilibrium Molecular Dynamics Simulation of the Rheology of Linear and Branched Alkanes (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 449-459 
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    ISSN: 1572-9567
    Keywords: alkanes ; nonequilibrium molecular dynamics ; order tensor ; rheology ; shear thinning ; viscosity ; viscosity index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Liquid alkanes in the molecular weight range of C20–C40 are the main constituents of lubricant basestocks, and their rheological properties are therefore of great concern in industrial lubricant applications. Using massively parallel supercomputers and an efficient parallel algorithm, we have carried out systematic studies of the rheological properties of a variety of model liquid alkanes ranging from linear to singly branched and multiply branched alkanes. We aim to elucidate the relationship between the molecular architecture and the viscous behavior. Nonequilibrium molecular dynamics simulations have been carried out for n-decane (C10H22), n-hexadecane (C16H34), n-tetracosane (C24H50), 10-n-hexylnonadecane (C25H52), and squalane (2, 6, 10, 15, 19, 23-hexamethyltetracosane, C30H62). At a high strain rate, the viscosity shows a power-law shear thinning behavior over several orders of magnitude in strain rate, with exponents ranging from −0.33 to −0.59. This power-law shear thinning is shown to be closely related to the ordering of the molecules. The molecular architecture is shown to have a significant influence on the power-law exponent. At a low strain rate, the viscosity behavior changes to a Newtonian plateau, whose accurate determination has been elusive in previous studies. The molecular order in this regime is essentially that of the equilibrium system, a signature of the linear response. The Newtonian plateau is verified by independent equilibrium molecular dynamics simulations using the Green–Kubo method. The reliable determination of the Newtonian viscosity from non-equilibrium molecular simulation permits us to calculate the viscosity index for squalane. The viscosity index is a widely used property to characterize the lubricant's temperature performance, and our studies represent the first approach towards its determination by molecular simulation.
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    URL: http://dx.doi.org/10.1023/A:1022565427881
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    Experimental study of the viscosity of lithium vapor at high temperatures (1986)
    Springer
    International journal of thermophysics 7 (1986), S. 829-835 
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    ISSN: 1572-9567
    Keywords: high temperature ; lithium vapor ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of lithium vapor was measured at temperatures from 1600 to 2000 K and pressures from 0.02 to 0.1 MPa with an experimental setup consisting of a closed circuit with a short annular channel used as a measuring element. The accuracy of the data obtained was estimated to be 3–4%. The characteristic features of the designed apparatus are the following: a high stability of the pressure difference within the viscometer during experiment, the absence of condensate accumulation out of the flowmeter, and a sufficiently large flowmeter volume. Since the length of the measuring section is short, the hydrodynamics of the gas flow through an annular channel were studied carefully. This enabled us to introduce the necesary corrections in the working equation. The results obtained are compared with available experimental data and the results of theoretical calculations.
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    The dilute-gas properties of some systems containing CO2 (1987)
    Springer
    International journal of thermophysics 8 (1987), S. 335-350 
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    ISSN: 1572-9567
    Keywords: carbon dioxide ; dilute gas ; mixtures ; virial coefficient ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The SSR-MPA potential model is used to correlate and extrapolate the dilutegas properties of some systems containing CO2. With parameters determined from a consistent set of second virial and Joule-Thomson data, the third virial coefficient of CO2 as well as the second virial coefficients of various mixtures containing CO2 can be predicted very well. The Mason-Monchik approximation fails for a complicated molecule such as CO2, although at least a viscosity prediction of technical accuracy is obtained. If parameters fitted to the CO2 viscosity are used, excellent predictions can be made for the viscosity of gaseous mixtures containing CO2.
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    Thermophysical Properties of Aqueous Solutions Near the Equilibrium Freezing Temperature (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 749-759 
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    ISSN: 1572-9567
    Keywords: aqueous solutions ; capillary-rise method ; surface tension ; thermal conductivity ; transient hot-wire method ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the surface tension, viscosity, and thermal conductivity of LiBr and LiSCN aqueous binary solutions have been performed to determine the thermophysical properties near the equilibrium freezing temperature. A differential capillary-rise method for surface tension and the transient hot-wire method for thermal conductivity were employed. Furthermore, a rotational viscometer was utilized for the measurement of viscosity. Correlation equations for the data of the aqueous binary test solutions as a function of temperature and concentration are presented.
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    URL: http://dx.doi.org/10.1023/A:1022626503214
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    The thermal conductivity and viscosity of benzene (1988)
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    International journal of thermophysics 9 (1988), S. 37-45 
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    ISSN: 1572-9567
    Keywords: benzene ; thermal conductivity ; transient hot-wire technique ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New absolute measurements of the thermal conductivity of liquid benzene are reported. The measurements have been carried out in the temperature range 295–340 K, at atmospheric pressure, in a transient hot-wire instrument. The accuracy of the measurements is estimated to be ±0.5%. The measurements presented in this paper have been used, in conjunction with other high-pressure measurements of thermal conductivity and viscosity, to develop a consistent theoretically based correlation for the prediction of these properties. The proposed scheme permits the density dependence of the thermal conductivity and viscosity of benzene, for temperatures between 295 and 375 K and pressures up to 400 MPa, to be represented successfully by two equations containing just two parameters characteristic of the fluid at each temperature.
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    Prediction of shear viscosity and non-Newtonian behavior in the soft-sphere liquid (1988)
    Springer
    International journal of thermophysics 9 (1988), S. 1041-1050 
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    ISSN: 1572-9567
    Keywords: non-Newtonian phenomena ; pair correlation function ; relaxation time ; soft-sphere liquid ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We show that a shear rate-dependent viscosity coefficient, normal pressure differences, and shear dilatancy can be predicted in a soft-sphere liquid given only the equilibrium radial distribution function and a relaxation time. Calculations are made using the relaxation-time theory of Hess and Hanley, and the results are compared with simulation data from nonequilibrium molecular dynamics.
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    The Effect of Model Internal Flexibility Upon NEMD Simulations of Viscosity (2000)
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    International journal of thermophysics 21 (2000), S. 45-55 
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    ISSN: 1572-9567
    Keywords: viscosity ; NEMD simulation ; flexible models ; rigid bond lengths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The influence of model flexibility upon simulated viscosity was investigated. Nonequilibrium molecular dynamics (NEMD) simulations of viscosity were performed on seven pure fluids using three models for each: one with rigid bonds and angles, one with flexible angles and rigid bonds, and one with flexible bonds and angles. Three nonpolar fluids (propane, n-butane, and isobutane), two moderately polar fluids (propyl chloride and acetone), and two strongly polar fluids (methanol and water) were studied. Internal flexibility had little effect upon the simulated viscosity of nonpolar fluids. While model flexibility did affect the simulated viscosity of the polar fluids, it did so principally by allowing a density-dependent change in the dipole moment of the fluid. By using a rigid model with the same geometry and dipole moment as the average flexible molecule at the same density, it was shown that the direct effect of flexibility is small even in polar fluids. It was concluded that internal model flexibility does not enhance the accuracy of viscosities obtained from NEMD simulations as long as the appropriate model geometry is used in the rigid model for the desired simulation density.
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    URL: http://dx.doi.org/10.1023/A:1006600719847
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    Densities, Viscosities, Sound Speeds, and Excess Properties of Binary Mixtures of Methyl Methacrylate with Alkoxyethanols and 1-Alcohols at 298.15 and 308.15 K (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 1153-1174 
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    ISSN: 1572-9567
    Keywords: density ; methyl methacrylate +alcohol binary liquid mixtures ; molecular interactions ; relative association ; solvation number ; sound speed ; viscosity
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract The densities, viscosities, and sound speeds were measured for six binary mixtures of methyl methacrylate (MMA)+2-methoxyethanol (ME), +2-ethoxyethanol (EE), +2-butoxyethanol (BE), +1-butanol (1-BuOH), +1-pentanol (1-PeOH), and +1-heptanol (1-HtOH) at 298.15 and 308.15 K. The mixture viscosities were correlated by Grunberg–Nissan, McAllister, and Auslander equations. The sound speeds were predicted by using free length and collision factor theoretical formulations, and Junjie and Nomoto equations. The excess viscosities and excess isentropic compressibilities were also calculated. A qualitative analysis of both of these functions revealed that structure disruptions are more predominant in MMA+1-alcohol than in MMA+alkoxyethanols mixtures. The estimated relative associations are found to become less in MMA+alcohol mixtures than in pure alcohols. The solvation numbers derived from the isentropic compressibility of the mixtures, considering MMA as a solvent, showed that structure making interactions are also present in MMA + alkoxyethanols in addition to the structure disruptions.
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    Transport properties of nonelectrolyte liquid mixtures—VII. Viscosity coefficients for isooctane and for equimolar mixtures of isooctane + n-octane and isooctane + n-dodecane from 25 to 100°C at pressures up to 500 MPa or to the freezing pressure (1985)
    Springer
    International journal of thermophysics 6 (1985), S. 233-250 
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    ISSN: 1572-9567
    Keywords: free volume ; Grunberg and Nissan equation ; high pressure ; isooctane ; n-dodecane ; n-octane ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Changes in the high-pressure self-centering falling-body viscometer system, and the new automated data logging system, are described. Viscosity coefficient measurements made with an estimated accuracy of ± 2 % are reported for isooctane and for equimolar mixtures of isooctane + n-octane and isooctane + n-dodecane at 25, 50, 75, and 100°C at pressures up to 500 MPa or to the freezing pressure. The pressure dependence of the results is found to be represented equally well by the recent equation of Makita and by a free-volume form of equation. The Grunberg and Nissan equation gives a good fit to the mixture viscosity coefficient data.
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    Shear viscosity of methanol and methanol + water mixtures under pressure (1985)
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    International journal of thermophysics 6 (1985), S. 439-450 
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    ISSN: 1572-9567
    Keywords: high pressure ; methanol ; mixtures ; viscosity ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Shear viscosities have been measured for methanol up to 400 MPa at 298, 313, and 323 K and for methanol-water mixtures (a) at 0.1 MPa and 278 K and (b) up to 300 MPa at 298 K. Where a comparison is possible the results are in good agreement with literature data. The data for the mixtures are discussed in terms of hydrogen bonding in methanol and water and by the use of excess viscosities.
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    Prediction of transport properties of dense gases and liquids by the Peng-Robinson (PR) equation of state (1989)
    Springer
    International journal of thermophysics 10 (1989), S. 133-144 
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    ISSN: 1572-9567
    Keywords: Enskog theory ; equation of state ; fluids (dense) ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An attempt is made in this work to combine the Enskog theory of transport properties with the simple cubic Peng-Robinson (PR) equation of state. The PR equation of state provides the density dependence of the equilibrium radial distribution function. A slight empirical modification of the Enskog equation is proposed to improve the accuracy of correlation of thermal conductivity and viscosity coefficient for dense gases and liquids. Extensive comparisons with experimental data of pure fluids are made for a wide range of fluid states with temperatures from 90 to 500 K and pressures from 1 to 740 atm. The total average absolute deviations are 2.67% and 2.02% for viscosity and thermal conductivity predictions, respectively. The proposed procedure for predicting viscosity and thermal conductivity is simple and straightforward. It requires only critical parameters and acentric factors for the fluids.
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    Density and viscosity of linear perfluoropolyethers under high pressures (1989)
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    International journal of thermophysics 10 (1989), S. 857-870 
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    ISSN: 1572-9567
    Keywords: compressibility ; density ; fluorocarbon oil ; free-volume equation ; high pressure ; perfluoropolyether ; specific volume ; Tait equation ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New experimental data on the density and viscosity of linear, unbranched perfluoropolyethers are presented at temperatures from 273 to 333 K and pressures up to 180 MPa. The measurements were carried out by a high-pressure burrette apparatus and a falling-cylinder viscometer. The uncertainties of the measurements are estimated to be less than 0.09% for the specific volume and 2.5% for the viscosity. The P-V data at each temperature are correlated satisfactorily by the Tait equation. The viscosity data are also analyzed and correlated with pressure or molar volume by several empirical and theoretical equations.
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    The shear viscosity and mutual diffusion coefficients of binary mixtures using the modified Enskog Theory (1989)
    Springer
    International journal of thermophysics 10 (1989), S. 963-971 
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    ISSN: 1572-9567
    Keywords: argon ; diffusion ; Enskog theory ; helium ; krypton ; mixtures ; modified Enskog theory ; neon ; virial coefficients ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We use an extended form of the modified Enskog Theory (MET) to calculate viscosity and mutual diffusion coefficients for several binary mixtures. Second and third virial coefficients are required for the calculations. We find that the extended MET provides predictions of the shear viscosity for He-Ar and Ne-Ar mixtures with an accuracy of 2% at densities up to 6 mol · L−1. Extended MET values of mutual diffusion coefficients of binary mixtures in which the mole fraction of one component approaches zero were calculated for He-Ar and Kr-Ar mixtures. The MET values fall within 10–15% of the experimental data at densities up to 11 mol · L−1.
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    Redetermination of the viscosity of molten NaCl at elevated temperatures (1989)
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    International journal of thermophysics 10 (1989), S. 819-831 
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    ISSN: 1572-9567
    Keywords: high temperature ; molten salt ; oscillation viscometer ; sodium chloride ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of molten sodium chloride (NaCl) has been measured in the temperature range 1083–1248 K by the oscillating-cup method. Although NaCl was considered as one of the standard salts, there existed a systematic deviation among the available data. The present measurement is the redetermination after checking the effects of the meniscus at the liquid surface and of the temperature field.
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    Density and viscosity of tetralin and trans-decalin (1989)
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    International journal of thermophysics 10 (1989), S. 845-856 
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    ISSN: 1572-9567
    Keywords: decalin ; density ; synfuels ; tetralin ; viscosity
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    Notes: Abstract New measurements are reported for the density and viscosity of tetralin and trans-decalin. The density was determined from room temperature to 60°C for tetralin and to 95°C for trans-decalin. The kinematic viscosity was measured up to temperatures slightly above 100°C. Our results improve upon the values recommended by the American Petroleum Institute for these liquids.
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    Thermophysical properties of natural gases for on-line metering (1995)
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    International journal of thermophysics 16 (1995), S. 195-204 
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    ISSN: 1572-9567
    Keywords: ethane ; gas metering ; methane ; natural gas ; prediction ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The evaluation of the background transport properties of natural gas multicomponent mixtures over a moderate temperature and pressure range around ambient is considered in the context of the development of certifiable sensors for the measurement of mass and energy fluxes. The best available, theoretically based procedures to predict the properties are compared with experimental information to test the internal consistency, accuracy, and range of validity of the prediction. This is of primary concern to the demonstration of the viability of such sensors. It is shown that for low to moderate pressures, it is possible to achieve an internal consistency of the order of a few parts in a thousand and an accuracy of better than ± I %. At very high pressures the predictive scheme is also satisfactory, with errors of the order of a few percent. However, the procedure employed here systematically underestimates the thermal conductivity of the gas mixtures studied for intermediate pressures owing to the neglect of the critical enhancement even for temperatures quite far removed from the critical. The range of conditions for which the critical enhancement of the thermal conductivity is significant in mixtures is explored with data for binary mixtures of methane and ethane.
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    A new apparatus for measuring high viscosity of solids (1995)
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    International journal of thermophysics 16 (1995), S. 577-584 
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    ISSN: 1572-9567
    Keywords: anelasticity ; laser interferometry ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new apparatus which is capable of measuring Newtonian viscosity as high as 108-1014 Pa · s has been developed. The upper and the lower faces of a cubic specimen 1 x 1 x I cm3 in size are respectively bonded to movable and fixed plates, and a constant shear stress is applied to the specimen. The displacement of the upper plate is measured and recorded as a function of time utilizing the HP-5528A optical laser measuring system. The sensitivity of the displacement measurement is 10 nm. Measurements at temperatures up to 200°C can be made by using a small furnace installed around the specimen. A variety of adhesive materials, polymers and ceramics, have been tested for the specimen-plate bonding. Aqueous Sauereisen cement showed a stable and rigid bonding in the experimental temperature range. Experiments for rubber (soft) and silicon crystal (hard) specimens have been performed to ascertain the reliability of the present method. The apparatus is also able to measure the anelasticity (mechanical relaxation) of solids, but is not adaptable to the measurement of the shear modulus of specimens; because the instantaneous displacement of the movable plate at the moment of the loading is mostly due to the rotational and inhomogeneous elastic deformations of the specimen.
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    Correlation and prediction of dense fluid transport coefficients. VII. Refrigerants (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 761-772 
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    ISSN: 1572-9567
    Keywords: density ; high pressure ; refrigerants ; Tail equation ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A recently developed scheme, based on considerations of hard-sphere theory, is used for the simultaneous correlation of the coefficients of viscosity and thermal conductivity for the refrigerants R11, R12, R22, R32. R124, R125, R134a, R141b, and R152a in excellent agreement with experiment, over extended temperature and pressure ranges. Values for the roughness factors and correlations for the characteristic volume are presented. The overall average absolute deviations of the experimental viscosity and thermal conductivity measurements from those calculated by the correlation are 2.1 and 2.3%, respectively, over a temperature range from 200 to about 10 K below the critical temperature and a pressure range from saturation to about 40 MPa. Since the proposed scheme is based on recent and accurate density values, a Tail-type equation was also employed to correlate successfully the density of the refrigerants. The overall average absolute deviation of the experimental density measurements from those calculated by the correlation is ±0.08%.
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    Correlation and extrapolation scheme for the composition and temperature dependence of viscosity of binary gaseous mixtures: Carbon dioxide + ethane (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1245-1255 
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    ISSN: 1572-9567
    Keywords: binary gaseous mixture ; carbon dioxide ; ethane ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental viscosity data of ethane, carbon dioxide, and three mole fractions of the binary system carbon dioxide + ethane in the temperature range 293.15〈T⩽633.15 K and in the density range 0.01⩽ρ⩽0.05 mol·L−1 reported earlier were evaluated simultaneously to find out a useful correlation and extrapolation scheme for the viscosity of binary systems in the range of moderate densities. A procedure based on the ideas of the modified Enskog theory has been found to give the best results. Dependent on temperature, the collision diameters related to the equilibrium radial distribution function at contact are fitted to viscosity values of the pure substances and of at least one mixture. The results are compared with experimental data from the literature. A recommendation is given concerning the density range in which the first density contribution to the viscosity coefficient of the system carbon dioxide + ethane is sufficient to be included.
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    Determination of the viscosity of various hydrocarbons and mixtures of hydrocarbons versus temperature and pressure (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1309-1334 
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    ISSN: 1572-9567
    Keywords: density ; high pressure ; hydrocarbons ; mixtures ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamic viscosityη and densityρ of 10 pure substances and three binary systems were measured as a function of temperatureT (298.15, 313.15, 333.15, 353.15, and 363.15 K.) and pressureP (⩽100 MPa). The pure substances were toluene,p-xylene,m-xylene,o-xylene, methylcyclohexane, methylnaphthalene, decahydronaphthalene, phenyldodecane, heptamethylnonane, and tetramethylpentadecane (pristane). The three binaries were toluene + tetramethylpentadecane, toluene + methylnaphthalene, and toluene + heptamethylnonane, for molar fractionsx of toluene ranging between 0 and 1. The three binaries are highly “contrasted” systems, i.e., systems in which the viscosities of the pure components are very different for eachP, T pair. In all, 547 experimental determinations were carried out (279 experimental data for viscosity of the pure substances and 268 data concerning the mixtures: x⊋0 and 1).
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    The viscosity of gaseous propane and its initial density dependence (1995)
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    International journal of thermophysics 16 (1995), S. 1335-1351 
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    ISSN: 1572-9567
    Keywords: n-alkanes ; propane ; second viscosity virial coefficient ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Results of five series of high-precision viscosity measurements on gaseous propane, each differing in density, are reported. The measurements were performed in a quartz oscillating-disk viscometer with small gaps from room temperature up to about 625 K and for densities between 0.01 and 0.05 mol · L−1. The experimental data were evaluated with a first-order expansion, in terms of density, for the viscosity. Reduced values of the second viscosity virial coefficients deduced from the zero-density and initial-density viscosity coefficients for propane and for furthern-alkanes are in close agreement with the theoretical representation of the Rainwater-Friend theory for the potential parameter ratios by Bich and Vogel. A new representation of the viscosity of propane in the limit of zero density is provided using the new experimental data and some data sets from literature. The universal correlation based on the extended principle of corresponding states extends over the temperature range 293 to 625 K with an uncertainty of ±0.5 % and deviates from earlier representations by about 1 % at the upper temperature limit.
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    Viscosities of HFC-32 and HFC-32/lubricant mixtures (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 75-83 
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    ISSN: 1572-9567
    Keywords: capillary viscometer ; free-volume model ; lubricant oil ; mixture ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A modified capillary tube method has been used to measure viscosities for HFC32 over a temperature range from -20 to 90°C and a pressure range from 0.1 to 5.3 M Pa, and for the liquid mixtures of HFC-32 with a synthetic polyolester oil at temperatures from 20 to 75°C and oil mass fractions from 0.44 to 1. Estimated uncertainties in the measured viscosities do not exceed ± 1.2 and ± 1.8°% for the pure fluocarbon and the mixtures, respectively. It is found that viscosity isotherms for HFC-32 at subcritical temperatures exhibit a minimum with increasing pressure, with the viscosity decreasing as much as 10% relative to its value at one atmosphere. Correlations are presented for dilute gas viscosities, excess viscosities, and saturated liquid and vapor viscosities. These correlations are shown to lit our data within experimental uncertainties. For HFC-32/lubricant mixtures, a free-volume viscosity model has been applied to correlate the experimental data.
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    URL: http://dx.doi.org/10.1007/BF01448211
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    The thermal conductivity and viscosity of acetic acid-water mixtures (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 111-125 
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    ISSN: 1572-9567
    Keywords: acetic arid ; aqueous mixtures ; thermal conductivity transient hot-wire technique ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity and thermal conductivity of acetic acid water mixtures were measured over the entire composition range and at temperatures ranging from 293 to 453 K. Viscosity measurements were performed with a high-pressure viscometer and thermal conductivity was measured using a modified transient hot-wire technique. A mercury filled. glass capillary was used as the insulated hot wire in the measurements. The l iscosity data showed unusual trends with respect to composition. At it given temperature. the viscosity was seen to increase with increasing acid concentration, attain a maximum. and then decrease. The thermal conductivity, on the other hand, decreased monotonically with acid concentration. A generalized corresponding-states principle using water and acetic acid as the reference fluids was used to predict both viscosity and thermal conductivity with considerable sucres.
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    URL: http://dx.doi.org/10.1007/BF01448214
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    Thermal conductivity and viscosity of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123) (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 293-328 
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    ISSN: 1572-9567
    Keywords: 2,2-dichloro-1,1,1-trifluoroethane ; HCFC-123 ; R123 ; thermal conductivity ; thermal diffusivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity and the viscosity data of CFC alternative refrigerant HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane: CHCI2-CF3) were critically evaluated and correlated on the basis of a comprehensive literature survey. Using the residual transport-property concept, we have developed the three-dimensional surfaces of the thermal conductivity-temperature-density and the viscosity-temperature-density. A dilute-gas function and an excess function of simple form were established for each property. The critical enhancement contribution was taken no account because reliable crossover equations of state and the thermal conductivity data are still missing in the critical region. The correlation for the thermal conductivity is valid at temperatures from 253 to 373 K, pressures up to 30 MPa, and densities up to 1633 kg m−3. The correlation for the viscosity is valid at temperatures from 253 to 423 K, pressures up to 20 MPa. and densities up to 1608 kg·m−3. The uncertainties of the present correlations are estimated to be 50% for both properties, since the experimental data are still scarce and somewhat contradictory in the vapor phase at present.
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    Saturated liquid viscosity correlations for alternative refrigerants (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 361-372 
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    ISSN: 1572-9567
    Keywords: ozone friendly ; refrigerants ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This article presents dimensionless equations for the temperature dependence of the saturated liquid viscosity of R32, R123 R124, R125, R134a. R141b. and R152a valid over a temperature range of engineering interest. The correlation has the form Φ n D =A +BT, where ΦD is the dimensionless fluidity (l ηD) andT D is a dimensionless temperature.n. A. andB are evaluated for each of the above refrigerants based on a least-squares fit to experimental data. This equation is found to provide an improved fit over those existing in the literature up toT D=0.8.
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    Excess volumes and excess viscosities of binary mixtures of 1-bromo-2-methylpropane + an isomer of butanol at 298.15 and 313.15 K (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 347-359 
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    ISSN: 1572-9567
    Keywords: activation energy ; binare mixtures ; free energy ; I-bromo-methypropane ; butanols ; viscosity ; excess volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Excess volumesV E, excess viscositiesη E, and excess free energies of activation of flow G*E at 298.15 and 313.15 K are reported for binary mixtures of 1-bronw-2-methypropane and each of the alcoholic isomers of I-butanol. The results were obtained from density and viscosity measurements and show positive values forV 4 and negative for bothη E andG *E for all mixtures over the entire composition range.
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    Mutual Diffusion Coefficient and Dynamic Viscosity Near the Critical Consolute Point Probed by Dynamic Light Scattering (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 791-803 
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    ISSN: 1572-9567
    Keywords: binary mixture ; critical consolute point ; dynamic light scattering ; mutual diffusion coefficient ; nitroethane–isooctane ; triethylamine–water ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The possibility of applying dynamic light scattering to simultaneous determination of the mutual diffusion coefficient and the viscosity of binary liquid systems was studied near the critical consolute point. When seed particles are added to the system, the particle diffusion coefficient is measured, and the viscosity is obtained using the Stokes–Einstein relation. Since the amplitude of light scattered from concentration fluctuations is low in a mixture with a small difference between the refractive indices of the pure components, this approach allowed the determination of the viscosity of a critical mixture of nitroethane and isooctane, without a signal component from mutual diffusivity superimposed. In contrast, particle aggregation prevented the determination of the viscosity of a critical mixture of triethylamine and water. Despite this difficulty, and an unidentified contribution in the signals obtained, the mutual diffusion coefficient and the critical exponent v could be determined in this system without a noticeable influence from the addition of seed particles.
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    URL: http://dx.doi.org/10.1023/A:1022670816359
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    Tests of Predictive Viscosity Models for Pure Liquids (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 815-823 
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    ISSN: 1572-9567
    Keywords: alkanes ; alkanols ; alkenes ; aromatics ; corresponding states ; cycloalkanes ; esters ; liquids ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is of considerable importance to be able to predict accurately the viscosity of liquids over a wide range of conditions. In the present work, the ability of the three-parameter generalized corresponding states principle (GCSP) for the prediction of the viscosity of pure liquids is demonstrated. The viscosity of six different classes of pure liquids, viz., alkanes (19 compounds; 207 data points), cycloalkanes (6 compounds; 74 data points), alkenes (9 compounds; 146 data points), aromatics (4 compounds; 123 data points), alkanols (8 compounds; 89 data points), and esters (4 compounds; 28 data points) have been predicted over a wide range of temperatures using the three-parameter (T c, P c, θ) GCSP. Five options for the third parameter (θ) were studied, viz., Pitzer's acentric factor ω, molar mass M, characteristic viscosity η*, critical compressibility factor Z c, and modified acentric factor Ω, in addition to groups ωZ c and ΩZ c being treated as composite third parameters. Pressure effects were neglected. Good agreement between experimental and predicted values of viscosity was obtained, especially with either ω or η* being used as the third parameter. Furthermore, the viscosities of alkanes predicted by the TRAPP method and an empirical, generalized one-parameter model for liquid hydrocarbons provide comparisons with the more accurate GCSP method. The GCSP provides a simple and yet a powerful technique for the correlation and prediction of viscosities of a variety of pure liquids over a wide range of temperatures.
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    Viscosity and Surface Tension Measurements in Microgravity (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1005-1015 
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    ISSN: 1572-9567
    Keywords: Co–Pd alloy ; electromagnetic levitation ; liquid metals ; microgravity ; Pd–Cu–Si alloy ; surface tension ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity and surface tension of liquid metals can be measured by observing the oscillations of a levitated drop. The frequency is related to the surface tension, while the viscosity determines the damping of the oscillations. If no external forces are present, as in microgravity, these relations are particularly simple and precise. During the recent Spacelab mission MSL-1, such experiments have been performed on Co–Pd and Pd–Cu–Si using the electromagnetic levitation facility TEMPUS. It was possible to obtain data over a wide temperature range, including the undercooled regime. While the temperature dependence of the surface tension remains linear over the complete range, the temperature dependence of the viscosity is much more pronounced and is discussed in terms of different models.
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    High-Temperature Containerless Viscosity Measurement by Gas-Film Levitation (1999)
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    International journal of thermophysics 20 (1999), S. 1071-1083 
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    ISSN: 1572-9567
    Keywords: gas-film levitation ; high temperature ; oxide melts ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The gas levitation process development program has, so far, been focused mainly on contact-free manipulation, on molding and shaping of liquids, on high-temperature contact-free treatment, and on shaping and solidification of interesting materials for scientific and technical purposes. Recently proposed by Parayre for viscosity measurements, this process eliminates the perturbing effects of the container, in particular, that of crystallization when studying supercooled liquids. The method consists of extracting viscosity values from the damped decay of perturbed liquid drops floating on a gas-film. An apparatus has been designed and developed for viscosity values higher than 1 Pa·s and at temperatures up to 2000°C. The method was applied to a silicate glass of industrial interest containing 70 wt% per cent of SiO2, with viscosities ranging from 102 to 106 Pa·s. Experimental results are compared with the Vogel–Fulcher–Tamann law for viscosity predictions. This paper demonstrates the industrial and scientific interest of this new method for viscosity determinations, which can be used for the working and softening points of any glass. These results may lead to a better understanding of network-forming or network-modifying behavior in oxide glasses.
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    Viscosity of Binary Mixtures of Alkyl Acetates with Hexane, Tetrachloromethane, and Trichloromethane (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1449-1465 
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    Keywords: alkyl acetate ; chloromethane ; Gibbs energy of activation ; hexane ; liquid mixtures ; molecular interactions ; tetrachloromethane ; trichloromethane ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity η for binary mixtures of methyl acetate (MA), ethyl acetate (EA), n-amyl acetate (nAA), isoamyl acetate (iAA), decyl acetate (DeA), and dodecyl acetate (DoA) with hexane and of MA, EA, nAA, and iAA with tetrachloromethane and trichloromethane has been measured at 303.15 K over the entire range of composition. The viscosity data have been correlated with the equations of Grunberg and Nissan; Hind, McLaughlin, and Ubbelohde; Tamura and Kurata; Katti and Chaudhri; McAllister; Heric and Brewer; and Auslaender. The viscosity deviations Δη and excess Gibbs energy of activation ΔG*E of viscous flow based on Eyring's theory have been calculated. The results have been analyzed in terms of disruption of dipolar association of alkyl acetate and molecular interaction between alkyl acetate and chloromethane.
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    Transport properties of 1,1-difluoroethane (R152a) (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 731-757 
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    ISSN: 1572-9567
    Keywords: 1,1-difluoroethane ; correlation ; critical region ; HFC-152a ; R152a ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Based on reliable. carefully selected data sets. equations for the thermal conductivity and the viscosity of the refrigerant R 112a are presented. They are valid at temperatures from 240 to 440 K, pressures up to 20 MPa. and densities up to 1050 kg · m−3. including the critical region.
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    Survey of Experimental Data of Thermophysical Properties for Difluoromethane (HFC-32) (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1653-1666 
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    ISSN: 1572-9567
    Keywords: critical parameters ; dielectric constant ; difluoromethane ; dipole moment ; heat capacities ; HFC-32 ; pvT behavior ; refractive index ; saturation densities ; second virial coefficient ; speed of sound ; surface tension ; survey ; thermal conductivity ; vapor pressure ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A survey of experimental data for HFC-32 was prepared at the Institute of Thermomechanics in connection with planned experiments. In tabular form, surveys of thermodynamic, transport, and other property measurements, including pvT behavior, second virial coefficient, vapor pressure, saturation densities, critical parameters, heat capacities, speed of sound, thermal conductivity, viscosity, surface tension, refractive index, dielectric constant, and dipole moment, are presented. Tables include author)s) name(s), reference, year of publication, ranges of measurements, number of points, stated uncertainty, sample purity, and experimental method.
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    Correlation for Viscosity and Thermal Conductivity of Liquid Halogenated Ethane Refrigerants1 (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 367-375 
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    ISSN: 1572-9567
    Keywords: correlation ; hard spheres ; liquid ; refrigerants ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity and thermal conductivity of liquid halogenated ethane refrigerants from about 200 K to near the critical temperature, at saturation and also at pressures up to 50 MPa, are shown to be satisfactorily correlated on the basis of a scheme developed by Dymond and Assael from consideration of hard-sphere theory.
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    New Correlation Functions for Viscosity Calculation of Gases Over Wide Temperature and Pressure Ranges (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 1011-1031 
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    ISSN: 1572-9567
    Keywords: dense fluids ; Rainwater–Friend theory ; second viscosity virial coefficient ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of 14 supercritical gases over a wide temperature–pressure range is calculated with a new correlation scheme. Highly accurate realistic interatomic potentials of the noble gases are used in the Chapman–Enskog calculation of the zero-density viscosity and in the Rainwater–Friend theory to determine the initial density dependence of the viscosity. At densities beyond the range of the theory, a variant of the residual viscosity is developed. It is shown that the temperature dependence of the residual viscosity function increases with the number of atoms in the molecule. By including this temperature dependence, the accuracy of the predicted results improves significantly. The accuracy of this method is within the experimental uncertainties.
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    Saturated Liquid Viscosity and Surface Tension of Alternative Refrigerants (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 1225-1253 
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    ISSN: 1572-9567
    Keywords: dynamic light scattering ; R23 ; R32 ; R123 ; R125 ; R134a ; R143a ; R152a ; refrigerants ; surface light scattering ; surface tension ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Light scattering by thermally excited capillary waves on liquid surfaces or interfaces can be used for the investigation of viscoelastic properties of fluids. In this work, we carried out the simultaneous determination of the surface tension and the liquid kinematic viscosity of some alternative refrigerants by surface light scattering (SLS) on a gas–liquid interface. The experiments are based on a heterodyne detection scheme and signal analysis by photon correlation spectroscopy (PCS). R23 (trifluoromethane), R32 (difluoromethane), R125 (pentafluoroethane), R143a (1,1,1-trifluoroethane), R134a (1,1,1,2-tetrafluoroethane), R152a (1,1-difluoroethane), and R123 (2,2-dichloro-1,1,1-trifluoroethane) were investigated under saturation conditions over a wide temperature range, from 233 K up to the critical point. It is estimated that the uncertainty of the present surface tension data for the whole temperature range is less than ±0.2 mN·m−1. For temperatures up to about 0.95T c, the kinematic viscosity of the liquid phase could be obtained with an absolute accuracy of better than 2%. For the highest temperatures studied in this work, measurements for the kinematic viscosity exhibit a maximum uncertainty of about ±4%. Viscosity and surface tension data are represented by a polynomial function of temperature and by a van der Waals-type surface tension equation, respectively. The results are discussed in detail with comparison to literature data.
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    Liquid Viscosity of Binary Mixtures of Methanol with Ethanol and 1-Propanol from 273.15 to 333.15 K (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 3-13 
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    ISSN: 1572-9567
    Keywords: ethanol ; methanol ; mixtures ; 1-propanol ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The liquid viscosities and densities of two binary mixtures of methanol with ethanol and 1-propanol were measured in the temperature range from 273.15 to 333.15 K with a capillary viscometer and a glass pycnometer, respectively. The uncertainties in the measured viscosities were estimated to be smaller than 1.3%. The experimental viscosity values could be fitted to the Mertsch and Wolf equation within 2%.
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    Viscosity and Excess Volume at High Pressures in Associative Binaries (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 161-189 
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    ISSN: 1572-9567
    Keywords: excess activation energy of flow ; excess volume ; high pressure ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamic viscosity η and the density ρ of three pure substances (water, 2-propanol, diacetone alcohol) and the three associated binaries were measured versus temperature T (303.15, 323.15, and 343.15 K) and pressure P. For the binary systems the mole fractions x of each component were, successively, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1. For viscosity the experimental results (P≤100 MPa) represent a total of 540 data points: 54 for the pure substances and 486 for the binary mixtures (x≠0 and x≠1). For density the experimental results (P≤70 MPa) represent 1260 values: 126 for the pure substances and 1134 for the binary mixtures (x≠0 and x≠1). The mixtures with water are highly associative and the curves for the variation of η with composition exhibit a maxima. The variations of the excess activation energy of viscous flow ΔG E are discussed. Moreover, the measurements of ρ are sufficiently accurate to determine the excess volumes V E versus pressure, temperature, and composition.
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    A High-Temperature Viscometer for Molten Materials (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 427-435 
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    ISSN: 1572-9567
    Keywords: high temperature ; molten salts ; oscillating-cup viscometer ; viscosity
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    Topics: Physics
    Notes: Abstract An oscillating-cup viscometer for the measurement of the viscosity of molten materials from room temperature to 1400 K was developed. The instrument is described in detail and the working equations are presented. The operational behavior was tested with water at room temperature. Preliminary measurements show that the new viscometer is capable of measuring the viscosity of water at room temperature to within 0.2%. As the primary objective of this work is the establishment of standard reference data for high-temperature viscosity measurements in molten salts, molten metals, and molten semiconductors, references of earlier viscosity measurements of molten KNO3 are given.
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    Correlation of the zero-density viscosity of polyatomic gases (1986)
    Springer
    International journal of thermophysics 7 (1986), S. 553-562 
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    ISSN: 1572-9567
    Keywords: carbon dioxide ; corresponding states ; methane ; polyatomic gases ; quadrupole ; sulfur hexafluoride ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Correlations are presented for the dilute-gas viscosities of three gases with multipole moments of increasing order: carbon dioxide (quadrupolar), methane (octopolar), and sulfur hexafluoride (hexadecapolar). These are based on highquality experimental data and are estimated to have an uncertainty of ±0.3% near room temperature, rising to ±1.5% at the extremes of temperature considered (≈200 to ≈1000 K). A comparison of these correlations with the two-parameter corresponding-states correlation developed by Kestin and co-workers for monatomic systems indicates systematic deviations, particularly at low temperatures. Model calculations designed to investigate the influence of a quadrupole term in the intermolecular pair potential on the viscosity coefficient indicate that these systematic deviations can be ascribed to such long-range multipolar interactions and suggest the basis for a new, more general three-parameter corresponding-states procedure.
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    Viscosities of nonelectrolyte liquid mixtures. I. n-hexadecane + n-octane (1987)
    Springer
    International journal of thermophysics 8 (1987), S. 649-662 
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    ISSN: 1572-9567
    Keywords: alkane ; congruence ; corresponding states ; density ; mixtures ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Viscosities and densities of the n-alkanes, hexane, heptane, octane, nonane, decane, dodecane, tetradecane, hexadecane, and tetracosane, were measured for temperatures from 303 to 338 K. Viscosities were measured using a standard Utube Ostwald viscometer; a pycnometer was used to measure both pure alkane and mixture densities. Results for the binary system n-hexadecane + n-octane at 318.16, 328.16, and 338.16 K are presented here, and comparisons with selected correlating equations are made.
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    Viscosity of aqueous solutions of 1,2-ethanediol and 1,2-propanediol under high pressures (1988)
    Springer
    International journal of thermophysics 9 (1988), S. 511-523 
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    ISSN: 1572-9567
    Keywords: aqueous alcohol solution ; ethanediol ; ethylene glycol ; falling-cylinder viscometer ; free-volume theory ; high pressure ; pressure effect ; propanediol ; propylene glycol ; viscosity ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New experimental data on the viscosity of aqueous solutions of 1,2-ethanediol (ethylene glycol) and 1,2-propanediol (propylene glycol) are presented at 298 and 323 K under pressures up to 120 MPa. The measurements were performed by a falling-cylinder viscometer on a relative basis with an uncertainty of less than ±2%. The viscosity of these aqueous solutions at a constant temperature and pressure increases monotonously with increasing concentrations of diols (glycols) and is slightly lower than the mole fraction average value at each composition. The viscosity also increases almost linearly with pressure at a constant temperature and composition. The pressure coefficient of the viscosity, (∂η/∂P)T,x, increases with decreasing temperature and increasing concentrations of diols. The experimental results are correlated with pressure, density, and composition by several empirical equations.
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    Transport properties of transparent liquids by photon-correlation spectroscopy (1988)
    Springer
    International journal of thermophysics 9 (1988), S. 897-909 
    Details
    ISSN: 1572-9567
    Keywords: diffusion ; light scattering ; photon-correlation spectroscopy ; thermal diffusivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Photon-correlation spectroscopy can be used for the fast and accurate determination of the transport properties thermal diffusivitya, mutual diffusion coefficientD, and viscosityη of transparent liquids over a wide range of temperature and pressure. Different detection techniques (homodyne, heterodyne) have to be used within the critical region and far away from it. Using optical arrangements with small scattering angles, the application of the heterodyne technique is recommended in order to assure a high measurement accuracy. The inaccuracy for a single measurement, which can be proved by a certain criterion, is estimated to be better than ±2 % fora and probably ±1 % forD andη. The principle of the measurement technique is presented in some detail on the basis of the heterodyne detection method. Selected measurements are shown for the determination ofa in pure liquids and in binary liquid mixtures, where the measurement situation is more complex, depending on the difference of the refractive index of both pure components. The determination ofD in binary liquid mixtures is treated in its context with the measurements ofa and also in a critical separation system typical for measurements within the critical region. Finally, the first results forη are given for atmospheric measurements in pure water near room temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01133258
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    Viscosity of Gaseous HFC-134a (1,1,1,2-Tetrafluoroethane) Under High Pressures (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1285-1295 
    Details
    ISSN: 1572-9567
    Keywords: HFC-134a ; Lennard–Jones potential ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of gaseous HFC-134a (1,1,1,2-tetrafluoroethane) was measured with an oscillating disk viscometer of the Maxwell type from 298.15 to 398.15 K at pressures up to 5.5 MPa. Intermolecular potential parameters for the Lennard–Jones 12-6 model were determined from the viscosity data at 0.1 MPa. The viscosity equation developed by Krauss et al. was applied to correlate the present viscosity data. In addition, the correlations proposed by Stiel and Thodos and by Lee and Thodos were tested for fitting the experimental viscosity data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021919215793
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    Prediction of the Viscosity of Supercritical Fluid Mixtures (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1297-1313 
    Details
    ISSN: 1572-9567
    Keywords: high pressure mixture ; supercritical fluids ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method for predicting the viscosity of supercritical, multicomponent fluid mixtures, at any density, from the zero-density viscosity of pure components is presented. The method is based upon the results for a rigid-sphere model, suitably interpreted to apply to real fluids, and on the finding that the excess viscosity of pure supercritical fluids can be adequately described by a density function independent of temperature. The density range of the method extends to twice the critical density of the pure component with the smallest critical density. The only exception is for the methane-rich mixtures where the mixture density should not exceed 12000 mol·m−3. The uncertainty ascribed to the predictions made by this method is of the order of ±5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021971232631
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    Viscosity of Aqueous Solutions of CO2 at High Pressures (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1315-1323 
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    ISSN: 1572-9567
    Keywords: carbon dioxide ; Flory's theory ; viscosity ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental viscosity measurements of aqueous solutions of CO2 along three isotherms at 273, 276, and 278 K for pressures up to 30 MPa are reported. The measurements have been carried out in a falling capillary viscometer and have an estimated uncertainty of ±1.5%. The experimental values were compared with the correlation proposed by Kanti et al. derived from Flory's theory. The equation is in poor agreement with the experimental values, but the equations of Kanti et al. and of Grunberg and Nissan with one adjustable parameter yield good agreement with the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021923316701
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    Viscosity and Density at High Pressures in an Associative Ternary (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1325-1341 
    Details
    ISSN: 1572-9567
    Keywords: density ; excess activation energy of viscous flow ; high pressure ; ternary mixture ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamic viscosity η and the density ρ of the associative ternary mixture water+diacetone alcohol+2-propanol have been measured as a function of temperature T (303.15, 323.15, and 343.15 K) and pressure P (≤100 MPa). The experimental results correspond to 698 values of η and ρ. With reference to the 54 values previously published on pure substances and 486 values for three corresponding binaries, the system is globally described by 1188 experimental values for various values of P, T and composition. The results for η are discussed in terms of excess activation energy of viscous flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021975300772
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    Liquid Densities, Kinematic Viscosities, and Heat Capacities of Some Ethylene Glycol Dimethyl Ethers at Temperatures from 283.15 to 423.15 K (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1343-1358 
    Details
    ISSN: 1572-9567
    Keywords: corresponding states ; density ; ethylene glycol dimethyl ether ; group-contribution method ; heat capacity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Liquid densities and heat capacities at 1 MPa, and kinematic viscosities at atmospheric pressure of monoethylene glycol dimethyl ether (MEGDME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TrEGDME), tetrathylene glycol dimethyl ether (TEGDME), pentaethylene glycol dimethyl ether (PeEGDME), and polyethylene glycol 250 dimethyl ether (PEGDME 250) were measured in the temperature range from 283.15 to 423.15 K. For each substance, experimental data were correlated with temperature using empirical polynomial equations. The experimental data were also used to evaluate the predictive capability of some estimation methods of liquid densities and heat capacities for the studied ethylene glycol dimethyl ethers. The densities estimated by the Yen–Woods equation agree with our experimental values with a root-mean-square relative deviation (RMSD) of 3.21% for all ethylene glycol dimethyl ethers. The best estimated results of liquid heat capacities were obtained from the Rowlinson equation based on the corresponding-states principle, with a RMSD of 1.12%. The group-contribution methods give the worst results, especially at high temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021927417610
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    Correlation and Prediction of the Transport Properties of Refrigerants Using Two Modified Rough Hard-Sphere Models (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 149-161 
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    ISSN: 1572-9567
    Keywords: viscosity ; thermal conductivity ; rough-hard-sphere ; refrigerants ; refrigerant mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two methods are presented for the correlation and prediction of the viscosities and thermal conductivities of refrigerants R11, R12, R22, R32, R124, R125, R134a, R141b, and R152 and their mixtures. The first (termed RHS1) is a modified rough-hard-sphere method based on the smooth hard-sphere correlations of Assael et al. The method requires two or three parameters for characterizing each refrigerant but is able to correlate transport properties over wide ranges of pressure and temperature. The second method (RHS2) is also a modified rough-hard-sphere method, but based on an effective hard-sphere diameter for Lennard–Jones (LJ) fluids. The LJ parameters and the effective hard-sphere diameter required in this method are determined from a knowledge of the density–temperature behavior of the fluid at saturation. Comparisons with the rough-hard-sphere method of Assael and co-workers (RHS3) are shown. We also show that the RHS2 method can be used to correlate as well as predict the transport properties of refrigerants.
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    URL: http://dx.doi.org/10.1023/A:1021438516081
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    Correlation of high-pressure diffusion and viscosity coefficients for n-alkanes (1989)
    Springer
    International journal of thermophysics 10 (1989), S. 941-951 
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    ISSN: 1572-9567
    Keywords: diffusion ; hard-sphere theory ; n-alkanes ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Self-diffusion coefficient and viscosity coefficient data for liquid n-alkanes over the whole pressure range at different temperatures are satisfactorily correlated simultaneously by a method which is just an extension of that previously used to apply the smooth hard-sphere theory of transport properties to individual transport coefficients. Universal curves are developed for reduced quantities D * and η * as a function of reduced volume. A consistent set of values is derived for the characteristic volume V 0 and for parameters R D and R η, introduced to account for effects of nonspherical molecular shape and molecular roughness. On this basis, accurate calculation can be made of self-diffusion and viscosity coefficients for other members of the n-alkane series, for which data are at present limited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00503163
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    Correlation of dense fluid self-diffusion, shear viscosity, and thermal conductivity coefficients (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 155-165 
    Details
    ISSN: 1572-9567
    Keywords: correlation methods ; dense liquids ; diffusion coefficient ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A general procedure has been developed for simultaneously fitting any two of the self-diffusion coefficient, the viscosity (as the fluidity), and the thermal conductivity (as its reciprocal) as Dymond reduced coefficients, (D*,η*,λ*), to a simple function of the volume and the temperature for dense fluids. For example,D*=ζ1+ζ2 V r/(1+ζ3,/V r), whereV r=V[1-ζ1(T−T r)-ζ2(T−T r)2].T r is any convenient temperature, here 273.15 K. AsV r is common to the two properties, only eight coefficients, ζj and ζk are required. Such reduced transport-coefficient curves are geometrically similar for members of groups of closely related compounds. The procedure has been extended to give “family” curves for such groups by fitting a pair of transport properties for three substances from the group in a single regression. Overall, fewer coefficients are required than for other schemes in the literature, and the fitting functions used are simpler. The curves so constructed can be used for the correlation of data obtained from different sources, as well as interpolation and, to a limited extent, extrapolation. A comparison is made for a number of compotmd groups between simultaneous fits of the pairs (D−η ), (D−λ), and (η−λ)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438966
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    Viscosity and density of liquid mixtures ofn-alkanes with squalane (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 773-779 
    Details
    ISSN: 1572-9567
    Keywords: capillary viscometer ; density ; n-butane ; n-hexane ; squalane ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Viscosity and density measurements are reported for binary liquid mixtures ofn-butane andn-hexane with squalane in the temperature range from 273 to 333 K. The viscosity measurements have been carried out by using a capillary viscometer calibrated with standard liquids. that is. JS5, JSIO, JS20, and water. The uncertainty in the viscosity data was estimated to be ± 1.7%. The density needed for the calculation of the viscosity has been measured by using a glass pycnometer within an accuracy of ±0.04%. In the prediction of the viscosity, the scheme of Assael et al. fails for mixtures of this type differing greatly in size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438862
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    Measurement of density, sound velocity, surface tension, and viscosity of freely suspended supercooled liquids (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 545-555 
    Details
    ISSN: 1572-9567
    Keywords: density ; levitation technique ; supercooling ; surface tension ; sound velocity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Noncontact methods have been implemented in conjunction with levitation techniques to carry out the measurement of the macroscopic properties of liquids significantly cooled below their nominal melting point. Free suspension of the sample and remote methods allow the deep excursion into the metastable liquid state and the determination of its thermophysical properties. We used this approach to investigate common substances such as water,v-terphenyl. succinonitrile, as well as higher temperature melts such as molten indium, aluminum, and other metals. Although these techniques have thus far involved ultrasonic, eletromagnetic, and more recently electrostatic levitation, we restrict our attention to ultrasonic methods in this paper. The resulting magnitude of maximum thermal supercooling achieved has ranged between 10% and 15% of the absolute temperature of the melting point for the materials mentioned above. The methods for measuring the physical properties have been mostly novel approaches, and the typical accuracy achieved has not yet matched the standard equivalent techniques involving contained samples and invasive probing. They are currently being refined, however, as the levitation techniques become more widespread and as we gain a better understanding of the physics of levitated liquid samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01441920
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    Viscosities of Multicomponent Silicate Melts at High Temperatures (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 309-323 
    Details
    ISSN: 1572-9567
    Keywords: experiment ; model ; silicate melts ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the present work; the viscosities in the quaternaries CaO–Fe n O–MgO–SiO2, Fe n O-MgO–MnO–SiO2, and CaO–MgO–MnO–SiO2 and the quinary CaO–Fe n O–MgO–MnO–SiO2 were studied. The experimental technique employed was the well-established rotating cylinder method, using a Brookfield digital viscometer mounted over a specially designed graphite furnace. Generally, iron crucibles were used along with iron spindles. Periodic calibrations of the experimental setup were made using the standard reference slag recommended by the European Union. The measurement's were carried out up to a maximum temperature of 1773 K in all cases. The reliability of the measurements were checked at different rotation speeds as well as during thermal cycling, and excellent reproducibility of the results was noted. The experimental viscosity values were incorporated into a viscosity model. Equations based on the model for calculating the viscosities of the quarternary systems CaO–Fe n O–MgO–SiO2, Fe n O–MgO–MnO–SiO2, and CaO–MgO–MnO–SiO2 and the quinary system CaO–Fe n O–MgO–MnO–SiO2 are provided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021419406512
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