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  • Articles  (270)
  • viscosity  (270)
  • Springer  (270)
  • American Geophysical Union
  • American Physical Society
  • Cell Press
  • Oxford University Press
  • Physics  (267)
  • Energy, Environment Protection, Nuclear Power Engineering  (3)
  • 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
    Pressure influences on the viscosity of polymer solutions (1982)
    Springer
    Rheologica acta 21 (1982), S. 505-507 
    Details
    ISSN: 1435-1528
    Keywords: Polystyrene solution ; viscosity ; pressure influence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01534331
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  • 3
    Electronic Resource
    Electronic Resource
    An empirical equation of the relative viscosity of polymer melts filled with various inorganic fillers (1981)
    Springer
    Rheologica acta 20 (1981), S. 207-209 
    Details
    ISSN: 1435-1528
    Keywords: Fiber ; suspension ; viscosity ; polymer ; melt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Summary Based on Maron-Pierce's equation, an empirical equation was suggested, which relates the relative viscosity (η r ) of the polymer melt filled with various inorganic filler, such as glass fiber, carbon fiber, talc, precipitated- and natural-calcium carbonate powder, and glassy small sphere, to the volume fraction (φ) of the filler. The equation isη r = (1 −φ/A)−2, whereA is a parameter relating to the packing geometry of the filler, which is similar to the parameterφ 0 in Maron-Pierce's equation. In the equationη r is defined as the ratio of the viscosity of the filledsystem to that of the medium at the same shear stress not the shear rate. The applicability of the equation is above the shear stress about 104 dyne/cm2. The equation has a simple form and is considered to have a practical utility for filled-polymer melt systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01513064
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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Flow behaviour of molten 2,4,6-trinitrotoluene (TNT) between concentric cylinders (1990)
    Springer
    Rheologica acta 29 (1990), S. 462-468 
    Details
    ISSN: 1435-1528
    Keywords: Flow curve ; coaxial cylinderviscometer ; trinitrotoluene melt ; turbulence ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The flow behaviour of pure and commercial molten TNT when subjected to very high rates of shear in a rotational viscometer over the temperature range 82.0 to 95.4°C is presented. All data obtained suggest that the behaviour of molten TNT is Newtonian, contrary to the conclusions of some published work, and the temperature dependence of the viscosity of pure TNT is adequately described by an Arrhenius-type relationship of the formη = A e B/T whereA = 0.000 541,B = 3 570 andT is the Kelvin temperature. A similar relationship is obtained for commercial TNT. Under some instrumental conditions discontinuities are seen in the shear stress—shear rate flow curves. An analysis of these discontinuities shows them to be caused by the transition from laminar to turbulent flow. Possible implications for processibility and initiation of explosives are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01376797
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Rheology of Lyocell Solutions from Different Cellulose Sources (2000)
    Springer
    Journal of polymers and the environment 8 (2000), S. 151-154 
    Details
    ISSN: 1572-8900
    Keywords: Lyocell ; cellulose ; rheology ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Rheological measurements were used to characterize the behavior of lyocell solutions, i.e., cellulose dissolved in N-methymorpholine-N-oxide. Cellulose sources included dissolving pulp, kraft pulp, sugar cane fibers, and kenaf fibers. The dominance of viscous behavior, G′ values, over elastic behavior, G″ values, is affected by cellulose concentration and molecular weight. At lower concentrations and degrees of polymerization (DP), dissolving pulp solutions show viscous, inelastic behavior at low frequencies. At higher concentration and DP, dissolving pulp solutions are more elastic at higher frequencies. Solutions prepared with kenaf and sugar cane fibers show similar properties to those using pure dissolving pulp, and comparisons suggest the molecular weight and/or the presence of other substances such as lignin in the cellulose from these alternative sources affect the rheology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1014881901010
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of Starch Granule Size on Viscosity of Starch-Filled Poly(hydroxy ester ether) Composites (2000)
    Springer
    Journal of polymers and the environment 8 (2000), S. 145-150 
    Details
    ISSN: 1572-8900
    Keywords: Starch ; particle size ; composite ; viscosity ; polyester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of starch granule size on the viscosity of starch-filled poly(hydroxy ester ether) (PHEE) composites was characterized using size-fractionated potato starch, as well as unfractionated starches (rice, corn, wheat, and potato). Potato starch was separated using an air classifier into four particle size fractions: 〈18 μm, 18-24 μm, 24-30 μm, and 〉30 μm. The starch was dried to a moisture content of 0.5% to minimize moisture effects on composite rheology. PHEE and potato starch were extruded with starch volume fractions of 0.46 and 0.66. Stress relaxation, frequency and strain sweep, and temperature-dependence measurements were carried out. Although small variations in viscosity were seen with the different potato starch fractions, differences were not significant at a volume fraction of 0.46. Viscosity differences between the different particle size fractions were more pronounced at a volume fraction of 0.66. The temperature dependence could be described by an Arrhenius relation, with an apparent activation energy of 84 kJ/mole. At a volume fraction of 0.46, the starch/PHEE viscosities increased in the order potato starch 〈 wheat starch ≃ corn starch 〈 rice starch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1014829916940
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  • 9
    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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  • 10
    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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  • 11
    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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  • 12
    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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  • 13
    Electronic Resource
    Electronic Resource
    Hydrodynamics and time correlation functions for cellular automata (1990)
    Springer
    Journal of statistical physics 58 (1990), S. 57-86 
    Details
    ISSN: 1572-9613
    Keywords: Cellular automata ; lattice gases ; mode coupling theory ; staggered modes ; Green-Kubo relations ; viscosity ; diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hydrodynamic excitations in lattice gas cellular automata are described in terms of equilibrium time correlation functions for the local conserved variables. For large space and time scales the linearized hydrodynamic equations are obtained to Navier-Stokes order. Exact expressions for the associated susceptibilities and transport coefficients are identified in terms of correlation functions. The general form of the time correlation functions for conserved densities in the hydrodynamic limit is given and illustrated by some examples suitable for comparison with computer simulation. The transport coefficients are related to time correlation functions for the conserved fluxes in a way analogous to the Green-Kubo expressions for continuous fluids. The general results are applied for a one-component fluid and several types of binary diffusion. Also discussed are the effects of unphysical slow modes such as staggered particle or momentum densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020285
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  • 14
    Electronic Resource
    Electronic Resource
    Phenomenological equations for multicomponent fluids (1972)
    Springer
    Journal of statistical physics 5 (1972), S. 113-125 
    Details
    ISSN: 1572-9613
    Keywords: Nonequilibrium thermodynamics ; electrolyte solution ; high-temperature plasma ; state variable ; forces and fluxes ; nonlocal linear relation ; Onsager reciprocity ; hydrodynamic equation of motion for component ; Navier-Stokes equation ; diffusion ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Ahydrodynamic equation of motion for each component of a multicomponent fluid is derived on the basis of nonequilibrium thermodynamics. Special care has been directed to the choice of state variables. In some limiting cases, this equation leads to customary phenomenological equations, such as the equation for diffusion and the Navier-Stokes equation. The viscosity is a consequence of nonlocal coupling of forces and fluxes. The reciprocity between the linear coefficients is examined closely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01008374
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  • 15
    Electronic Resource
    Electronic Resource
    Reflection and transmission ofSH waves in an initially stressed medium consisting of a sandy layer lying over a fluid-saturated porous solid (1993)
    Springer
    Pure and applied geophysics 140 (1993), S. 613-628 
    Details
    ISSN: 1420-9136
    Keywords: Propagation ; poroelastic ; viscosity ; anelasticity, dissipation, interstitial fluid, energy, parfition ; initial stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Biot's theory is employed to study the reflection and transmission ofSH waves in a sandy layer lying over a fluid-saturated porous solid half-space. The entire medium is considered under constant initial stress. Effects of sandiness, initial stress, anelasticity and viscosity of the interstitial fluid on the partitioning of energy are studied. In the presence of initial stress the incident wave starts attenuating when incider beyond a certain angle (depending upon the amount of initial stress), even if the medium is perfectly clastic. Anelasticity of the solid layer results in the dissipation of energy during transmission. The direction of attenuation vector of incident wave affects the dissipation energy to a large extent. Effect on partitioning of energy reverse at incidence after the critical angle. A complete account of energy returmed back to the underlying half-space and that which is dissipated in the overlying layer has been discussed analytically as well as numerically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876579
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  • 16
    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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  • 17
    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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  • 18
    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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  • 19
    Electronic Resource
    Electronic Resource
    Fluorescence probes of viscosity: A comparative study of the fluorescence anisotropy decay of perylene and 3,9-dibromoperylene in glycerol (1993)
    Springer
    Journal of fluorescence 3 (1993), S. 247-249 
    Details
    ISSN: 1573-4994
    Keywords: Fluorescence anisotropy decay ; rotational diffusion ; viscosity ; perylene ; 3,9-dibromoperylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The authors compare the results of fluorescence anisotropy decay measurements for glycerol solutions of perylene with those of 3,9-dibromoperylene (DBP). For both molecules a good linear dependence is observed between the glycerol viscosity (varied by temperature) and the longer rotational correlation time obtained as a result of a global (using data obtained at 256- and 430-nm excitation wavelengths) biexponential analysis of the fluorescence anisotropy decay, at least in the range of 7–60 P for perylene and 4–60 P for DBP. This significantly extends the reported range of 0.5 to 150 cP investigated by Williams and Ben-Amotz [1] with the probe BTBP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00865272
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  • 20
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    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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  • 21
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    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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  • 22
    Electronic Resource
    Electronic Resource
    Excluded volume and hydrodynamic properties of polystyrene in non-ideal solvents (1993)
    Springer
    Polymer bulletin 30 (1993), S. 579-586 
    Details
    ISSN: 1436-2449
    Keywords: polystyrene ; hydrodynamic ; excluded volume ; binary solvents ; viscosity ; θ-condition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract At 298 K, intrinsic viscosity [η], has been measured for fifteen polystyrene, PS, samples of different relative molar masses M in pure toluene T, and seven different binary solvents. These solvents were toluene / methanol (MeOH) mixtures having different volume fractions of MeOH. The θ-composition for the binary solvent system was found to be 77% T / 23% MeOH at 298 K. The dependance of excluded volume of polymer molecules on M and the solvation power was demonstrated. A constant value of 0.633 nm for the effective unit length, b, was obtained under θ-condition. Meanwhile a non-constancy of b, obtained in case of thermodynamically good solvents, was attributed to the neglect of excluded volume effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296478
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  • 23
    Electronic Resource
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    The time, temperature and shear dependence of the viscosity of polypropylene and its influence upon the extrusion process (1982)
    Springer
    Rheologica acta 21 (1982), S. 470-474 
    Details
    ISSN: 1435-1528
    Keywords: Polypropylene ; viscosity ; degradation ; master curve ; extrusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The polypropylene melt viscosity dependence upon temperature, shear and molecular weight, and the molecular weight dependence upon temperature and time were measured and mathematically described. For the dependence of the melt viscosity upon temperature, shear and molecular weight (melt index), a master curve has been found. The influence of the progressive degradation of polypropylene during the extrusion upon the temperature, pressure and dissipated energy down-channel profiles is given.
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    URL: http://dx.doi.org/10.1007/BF01534321
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    Der Einfluß des Zusatzes von Hemicellulosen auf die Fließeigenschaften von Weizenmehlteig (1984)
    Springer
    Rheologica acta 23 (1984), S. 570-572 
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    ISSN: 1435-1528
    Keywords: Hemicellulose ; wheat flour ; viscosity ; adsorption of water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The water adsorption capacity of a dough consisting of wheat flour was increased linearly by the addition of water-insoluble hemicelluloses (xylane, mannane etc.) extracted from beech-wood pulp using soda lye (a by-product of viscose fiber production). The investigation of this finding by viscosity measurements revealed two reasons for the higher water uptake: 1) a higher kneading resistance of the dough, and 2) a gel-regeneration of the kneaded dough during the dough-rest.
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    URL: http://dx.doi.org/10.1007/BF01329291
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    Viscosity of some clay-based coating colors at high shear rates (1990)
    Springer
    Rheologica acta 29 (1990), S. 352-359 
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    ISSN: 1435-1528
    Keywords: Coatingcolors ; viscosity ; clay ; solids content ; carboxymethyl cellulose ; particle size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The shear viscosity of clay-based coating colors containing latex and carboxymethyl cellulose (CMC) has been measured over a relatively large shearrate region. In the shear-rate range of 50–1500 s−1 the measurements were performed using a rotational viscometer and, at higher shear rates extending into the region 105 − 106 s−1, a high pressure capillary viscometer was employed. The viscosity of the clay colors increased with increasing CMC-concentration, but the influence of the CMC-content was less pronounced at higher shear rates. The apparent shear-thinning behavior of the investigated colors could, in part, be attributed to the shear-thinning of the corresponding polymer (CMC) solution constituting the liquid phase of the color, but the influence of another factor was also indicated. At low shear rates, the interaction between the color components can produce relatively high viscosity levels, but in the high shear rate region these interactions appear to be less important for the viscosity level. It is also of interest to note that the viscosity dependence on the solids content in the high shear-rate region could be described with reasonable accuracy using an empirical equation neglecting interactions between the color components.
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    URL: http://dx.doi.org/10.1007/BF01339890
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    Rheological characterization of bimodal colloidal dispersions (1994)
    Springer
    Rheologica acta 33 (1994), S. 165-174 
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    ISSN: 1435-1528
    Keywords: Colloidal suspensions ; bimodal dispersion ; viscosity ; dynamic moduli ; steric stabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract In order to investigate the effect of the particle size distribution on the rheological properties of concentrated colloidal dispersions both steady-state shear and oscillatory measurements have been performed on well-characterized bimodal dispersions of sterically stabilized PMMA particles. Replacing a minor amount of large particles by small ones in a concentrated dispersion, keeping the total effective volume fraction constant, decreases the viscosity quite drastically. On the other hand, replacing a small amount of small particles by big ones hardly effects the viscosity at all. This behavior can be attributed to the deformability of the stabilizing polymer layer. A procedure is proposed to calculate the limiting viscosities in a bimodal colloidal dispersion starting from the characteristics of the monodisperse systems. A good agreement has been obtained between the calculated values and the experimental results. The linear viscoelastic properties of the concentrated dispersions have been investigated by means of oscillatory measurements. The plateau values of the storage modulus for the bimodal dispersions decrease with an increasing fraction of the coarse particles. By substituting the bimodal dispersion by an equivalent monodisperse system the storage modulus can be superimposed on the values for the monodisperse suspensions when plotted as a function of the mean interparticle distance.
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    URL: http://dx.doi.org/10.1007/BF00437301
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    On-line measurement of elasticity and viscosity in flowing polymeric liquids (1996)
    Springer
    Rheologica acta 35 (1996), S. 110-116 
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    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.
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    URL: http://dx.doi.org/10.1007/BF00396037
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    Curing effects on viscosity of reactive epoxy resin adhesives (1996)
    Springer
    Rheologica acta 35 (1996), S. 321-328 
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    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.
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    URL: http://dx.doi.org/10.1007/BF00403532
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    Translational diffusion of rubrene and tetracene in polyisobutylene (1997)
    Springer
    Rheologica acta 36 (1997), S. 209-216 
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    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.
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    Translational diffusion of rubrene and tetracene in polyisobutylene (1997)
    Springer
    Rheologica acta 36 (1997), S. 209-216 
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    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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    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: Key words 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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    Effective viscosity of porous particle suspensions (1997)
    Springer
    Rheologica acta 36 (1997), S. 483-484 
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    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.
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    URL: http://dx.doi.org/10.1007/BF00396333
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    Effective viscosity of porous particle suspensions (1997)
    Springer
    Rheologica acta 36 (1997), S. 483-484 
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    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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    Rheological determination of polymer-filler affinity (1982)
    Springer
    Rheologica acta 21 (1982), S. 103-105 
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    ISSN: 1435-1528
    Keywords: Affinity ; copolymer ; filler ; polypropylene ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract An experimental method to quantify the affinity of polymers for certain fillers is presented. In this method, the relative viscosity of filled and unfilled polymer systems as determined by capillary rheometry is taken as a measure of the thickness of the adsorbed layer of polymeric material on the filler surface and hence of the affinity of the polymer for the filler. A styrene-butadienestyrene block copolymer is thus found to have a higher affinity for talc than do polypropylene and an ethylene-propylene-diene terpolymer.
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    Viscoplasticity of agglomerated suspensions (1989)
    Springer
    Rheologica acta 28 (1989), S. 311-315 
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    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.
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    Shear dependence of viscosity for perfluoropolyether fluids (1986)
    Springer
    Rheologica acta 25 (1986), S. 69-71 
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    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.
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    The fluidity of molten salts (1981)
    Springer
    Rheologica acta 20 (1981), S. 203-206 
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    ISSN: 1435-1528
    Keywords: Fluidity ; molten salt ; free volume ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Summary The fluidity,φ, of a molten salt is directly proportional to the relative free volume (V − V 0)/V 0. Although the parameterV 0 is closely related to the molar volume of the solid near the melting point the proportionality constant is difficult to interpret in terms of the microscopic or thermodynamic properties of the salt.
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    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 
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    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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    Cluster statistics in a bidimensional suspension: Comparison with percolation (1983)
    Springer
    Rheologica acta 22 (1983), S. 505-511 
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    Keywords: Suspension ; cluster statistics ; viscosity ; percolation
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract We study the cluster statistics and the viscosity of a two-dimensional suspension of passive macroscopic spheres undergoing shear. The second moment of the finite cluster statistics exhibits a maximum for a 2-D concentrationΦ S near 0.67 without measurable anomaly in the viscosity. The results of the cluster statistics are compared to those obtained in percolation.
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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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    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 experimental study of exit pressures for polymer melts (1990)
    Springer
    Rheologica acta 29 (1990), S. 60-70 
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    ISSN: 1435-1528
    Keywords: Exitpressure ; first normalstress difference ; viscosity ; polymermelts ; slitdie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A slit die apparatus is used to measure exit pressures for five different polymer melts. Viscosity data obtained from the same apparatus agree well with values obtained from a cone-and-plate rheometer or a capillary rheometer. Except for a PVC sample where thermal degradation was found to occur, the exit pressures obtained by linear extrapolation of the measured pressure profiles are all positive, and increase with increasing shear stress. The values of the first normal stress difference calculated according to the exit pressure theory are of the right order of magnitude and in some cases correlate satisfactorily with values measured in a cone-and-plate rheometer. However, the high sensitivity of the exit pressure values to the method of extrapolation and the wild scatter of exit pressure data for some materials make it difficult to use the exit pressure method as a routine procedure for accurate determination of the first normal stress difference.
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    Positive and negative flow and viscosity of clay suspensions (1982)
    Springer
    Rheologica acta 21 (1982), S. 647-649 
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    ISSN: 1435-1528
    Keywords: Positive and negative flow ; viscosity ; non-Newtonian liquid ; transformed flow tensor ; clay suspension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
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    URL: http://dx.doi.org/10.1007/BF01534370
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    Zum rheologischen Verhalten konzentrierter Dispersionen organischer Polymere (1982)
    Springer
    Rheologica acta 21 (1982), S. 644-646 
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    ISSN: 1435-1528
    Keywords: PVC-plastisol ; particle size distribution ; viscosity ; interface ; stratifiedflow model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Abstract The dependence of the apparent shear viscosity on parameters of the particle size distribution is investigated on mono- and polydisperse PVC-E-suspensions. For equal size distributions, differences in the rheological behaviour are reduced to properties of the interface between disperse and fluid phases. The thickness of the interface is estimated from the deviation of the “Einstein behaviour”. The flow behaviour of concentrated PVC-plasticizer suspensions can be described by various model theories.
    Notes: Zusammenfassung Die Abhängigkeit der scheinbaren Scherviskosität von den Parametern der Teilchengrößenverteilung wird an monodispersen und polydispersen PVC-E-Suspensionen untersucht. Unterschiede im rheologischen Verhalten werden bei gleicher Größenverteilung auf die Eigenschaften der Grenzfläche zwischen disperser und fluider Phase zurückgeführt. Deren Schichtdicke bestimmt sich aus der Abweichung vom „Einstein-Verhalten“. Zur Beschreibung des Fließverhaltens konzentrierter PVC-Weichmacher-Suspensionen können verschiedene Modell-Theorien herangezogen werden.
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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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    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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    Semi-empirical theory of the viscosity of moderately dilute polymer solutions (1986)
    Springer
    Rheologica acta 25 (1986), S. 487-493 
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    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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    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
    Source: Springer Online Journal Archives 1860-2000
    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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    The effect of pH, ionic strength, and temperature on the rheology and stability of aqueous clay suspensions (1993)
    Springer
    Rheologica acta 32 (1993), S. 263-269 
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    ISSN: 1435-1528
    Keywords: Aqueous clay suspensions ; suspension stability ; viscosity ; ionic strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The effect of pH level, ionic strength, and temperature on the theology and stability of aqueous suspensions of attapulgite clay was systematically investigated. A Rheometrics Mechanical Spectrometer with cone and plate fixtures was used to measure the steady shear viscosity of the system. The edge charges of the clay particles can be adjusted by changing the pH level of the suspending medium so as to influence the flocculation state and, consequently, the rheological behavior of the suspension. This pH effect may be counteracted by the ionic strength effect at both very high and very low pH levels where the ionic strength is high enough to cause flocculation of the electrostatically stabilized suspension. The temperature effect study indicates that the relative contribution of Brownian motion and shear flow to the viscosity is dependent on the flocculation state of the suspension.
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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
    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.
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    Viscosity properties of mineral paraffinic base oils as a key factor in their primary biodegradability (2000)
    Springer
    Biodegradation 11 (2000), S. 365-369 
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    ISSN: 1572-9729
    Keywords: aromatic hydrocarbons ; biodegradation ; CEC L-33-A-93 test ; lubricants ; mineral base oils ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The primary biodegradability of two types of paraffinic base oils (solvent and catalytically dewaxed oils) and their blends was evaluated using the CEC L-33-A-93 test. The biodegradability values varied between 10% and 75%. Base oil mixtures displayed varying contents in aromatic and polar compounds and a wide range of kinematic viscosity (KV) values, from roughly 10 to 600 cSt (at 40°C), while their viscosity indices were almost constant (90-100). The biodegradability of oils was closely related to their content in polycyclic aromatic hydrocarbons and was also decreasing with kinematic viscosity. For the two types of base oils, a linear relationship could be set between the biodegradation percentages and the logarithms of KV values. These results show that, beside overall chemical features such as the contents in aromatic compounds, KV may be a prominent parameter for assessing the primary biodegradability of mineral base oils.
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    Tail shortening by discrete hydrodynamics (1982)
    Springer
    Journal of statistical physics 27 (1982), S. 389-405 
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    ISSN: 1572-9613
    Keywords: Molecular dynamics ; transport coefficients ; viscosity ; time correlation functions ; long-time tails
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A discrete formulation of hydrodynamics was recently introduced, whose most important feature is that it is exactly renormalizable. Previous numerical work has found that it provides a more efficient and rapidly convergent method for calculating transport coefficients than the usual Green-Kubo method. The latter's convergence difficulties are due to the well-known “long-time tail” of the time correlation function which must be integrated over time. The purpose of the present paper is to present additional evidence that these difficulties are really absent in the discrete equation of motion approach. The “memory” terms in the equation of motion are calculated accurately, and shown to decay much more rapidly with time than the equilibrium time correlations do.
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    Rheology of suspensions of rodlike particles (1991)
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    Journal of statistical physics 62 (1991), S. 1073-1094 
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    ISSN: 1572-9613
    Keywords: Rheology ; rods ; viscosity ; aspect ratio ; suspension
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    Topics: Physics
    Notes: Abstract Suspensions of rigid rodlike particles in Newtonian suspending fluids are considered. We discuss the dependence of the relative viscosityμ r upon the volume fraction of particlesϕ, their aspect ratioa r, and the particle orientation distribution when the particles are sufficiently large that hydrodynamic forces are dominant. Theoretical results are reviewed for a variety of long slender particles. Experimental results obtained using classical rheometrical techniques are discussed. It is shown that whena r⩽25, data from several laboratories agree and they indicate thatμ r depends more strongly uponϕ thana r. Previous experimental results using falling ball rheometry are discussed as well as some more recent findings. These are shown to provide insights heretofore unavailable into the macroscopic rheology of suspensions of randomly oriented and oriented rods.
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    Note on transport processes in dense colloidal suspensions (1991)
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    Journal of statistical physics 63 (1991), S. 241-248 
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    ISSN: 1572-9613
    Keywords: Transport coefficients ; cage diffusion ; viscosity ; colloidal suspensions ; hard-sphere fluids ; intermediate scattering function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new approach to transport processes in dense charged as well as neutral colloidal suspensions is presented. It is based on a far-reaching analogy between dense colloidal suspensions and dense hard-sphere fluids, implying, in turn, an analogy with atomic liquids. As a result, new expressions valid for a number of colloidal transport coefficients are predicted.
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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
    Source: Springer Online Journal Archives 1860-2000
    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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    Transport phenomena in a plane shock wave (1991)
    Springer
    Journal of statistical physics 64 (1991), S. 429-436 
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    ISSN: 1572-9613
    Keywords: Shock wave ; Boltzmann equation ; Mott-Smith theory ; nonpolynomial closure ; transverse temperature ; viscosity ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract With the use of the nonpolynomial closure 1/ν z in the Mott-Smith approximation of the solution of the Boltzmann equation, we obtain a value of the density gradient in the limit of a very weak shock wave that is close to the correct value. For the determination of the transverse temperature gradient we calculated theν x 2 /ν z moment of the Mott-Smith collision integral. The effective values of viscosity and thermal conductivity in the limit of a very weak shock wave were calculated for inverse-power potentials and found to agree almost exactly with the Chapman-Enskog values. Such a comparison can serve as a criterion for the evaluation of different bimodal theories. Various bimodal theories give different values of viscosity and thermal conductivity, but all of them give 33 % too high a value of the Eucken ratio.
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    Characteristics and mechanisms of electrorheological fluids (1991)
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    Journal of statistical physics 64 (1991), S. 1073-1091 
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    ISSN: 1572-9613
    Keywords: Electrorheology ; yield stress ; Bingham solid ; viscoelasticity ; dielectric constant ; electric field ; fibrous structure ; dipole moment ; suspension ; attractive force ; viscosity ; Mason number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electrorheological (ER) fluids consist of suspensions of fine polarizable particles in a dielectric medium, which upon application of an electric field take on the characteristics of a solid in times of the order of milliseconds and reversibly return to liquid behavior upon removal of the field. The rheology, electrical characteristics, and structure of typical ER fluids are here reviewed. The proposed mechanisms and their accord with experimental data are discussed. Some directions for future research are mentioned.
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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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    Nonequilibrium Brownian dynamics simulations of shear thinning in concentrated colloidal suspensions (1991)
    Springer
    Journal of statistical physics 62 (1991), S. 1239-1253 
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    ISSN: 1572-9613
    Keywords: Colloidal suspensions ; viscosity ; shear thinning ; Brownian dynamics
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    Topics: Physics
    Notes: Abstract The effect of interparticle forces on shear thinning in concentrated aqueous and nonaqueous colloidal suspensions was studied using nonequilibrium Brownian dynamics. Hydrodynamic interactions among particles were neglected. Systems of 108 particles were studied at volume fractionsφ of 0.2 and 0.4. For the nonaqueous systems, shear thinning could be correlated with the gradual breakup of small flocs present because of the weak, attractive secondary minimum in the interparticle potential. At the highest shear rate forφ=0.4, the particles were organized into a hexagonally packed array of strings. For the strongly repulsive aqueous systems, the viscosity appeared to be a discontinuous function of the shear rate. Forφ=0.4, this discontinuity coincided with a transition from a disordered state to a lamellar structure for the suspension.
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    Modeling of concentrated suspensions (1991)
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    Journal of statistical physics 62 (1991), S. 1225-1237 
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    ISSN: 1572-9613
    Keywords: Concentrated suspension ; volume averaging ; viscosity ; stress tensor ; lubrication approximation
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    Topics: Physics
    Notes: Abstract The constitutive equation of a concentrated suspension of spherical particles in a Newtonian medium is derived. To this end the method of local volume averaging is employed. To calculate the contribution of the particles to the stress tensor it is assumed that the stress generated in the interstitial holes between the particles is negligible compared to the stress generated in !he narrow gaps separating the particles. The use of the resulting expression is demonstrated with two examples on a cubical arrangement of particles: pure shear and simple shear. Furthermore, the validity of the lubrication approximation employed in this work is checked against the results derived by Nunan and Keller for periodic suspensions.
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    Viscosity of steam in the critical region (1980)
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    International journal of thermophysics 1 (1980), S. 33-50 
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    ISSN: 1572-9567
    Keywords: critical region ; critical viscosity enhancement ; steam ; viscosity ; water ; water vapor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The shear viscosity of fluids exhibits an anomalous enhancement in the close vicinity of the critical point. A detailed experimental study of the viscosity of steam in the critical region has been reported by Rivkin and collaborators. A reanalysis of the experimental data indicates that the behavior of the viscosity of steam near the critical point is similar to that observed for other fluids near the critical point. An interpolating equation for the viscosity of water and steam is presented that incorporates the critical viscosity enhancement.
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    Transport properties of nonelectrolyte liquid mixtures—I. Viscosity coefficients for n-alkane mixtures at saturation pressure from 283 to 378 K (1980)
    Springer
    International journal of thermophysics 1 (1980), S. 331-344 
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    ISSN: 1572-9567
    Keywords: viscosity ; n-alkane mixtures ; congruence principle ; Grunberg and Nissan equation
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    Topics: Physics
    Notes: Abstract Viscosity coefficient measurements at saturation pressure are reported for n-hexane + n-hexadecane, n-hexane + n-octane + n-hexadecane, and n-hexane + n-octane + n-dodecane + n-hexadecane at temperatures from 283 to 378 K. The results show that the Congruence Principle applies to the molar excess Gibbs free energy of activation for flow, δ* G E, at temperatures other than 298 K. However, curves of δ* G E versus index number of the mixture are temperature dependent, and this must be taken into account for accurate prediction of mixture viscosity coefficients by this approach. The purely empirical equation of Grunberg and Nissan; 1 $$\ln \eta = x_1 \ln \eta _1 + x_2 \ln \eta _2 + x_1 x_2 G$$ which has the advantage of not involving molar volumes, satisfactorily reproduces the experimental results for the binary mixture, but G is definitely composition dependent.
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    The prediction of the viscosity of dense gas mixtures (1989)
    Springer
    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)
    Springer
    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
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    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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    Thermodynamic and transport properties of 1, 2-dichloroethane (1990)
    Springer
    International journal of thermophysics 11 (1990), S. 835-861 
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    ISSN: 1572-9567
    Keywords: compressibility ; dichloroethane ; diffusion ; high pressure ; p, V, T, data ; rough hard sphere ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract (p, V, T) data for dichloroethane (DCE) have been obtained at 278.15, 288.15, 298.15, 313.15, 323.15, and 338.15 K for pressures either slightly below the freezing pressure or up to a maximum of 280 M Pa, together with densities at 0.1 MPa. A high-pressure self-centering falling-body viscometer method has been used to measure shear viscosities at 278.15, 288.15, 298.15, 313.15, and 323.15 K for pressures either slightly below the freezing pressure or up to a maximum of 330 MPa. Self-diffusion coefficients for DCE are reported at 278.15, 288.15, 298.15, and 313.15 K for maximum pressures up to 300 MPa. Isothermal compressibilities, isobaric expansivities, and internal pressures have been evaluated from the volumetric data. The shear viscosities and self-diffusion coefficients have been interpreted in terms of a modified rough hard-spheres theory. The anomalous behavior observed for p-V-T, shear viscosities, and self diffusion at higher temperatures and pressures is suspected to be the result of temperature and pressure altering the population ratio of the two molecular conformers, trans and gauche.
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    Viscosity and thermal conductivity of alkali metal vapors at temperatures up to 2000 K (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 85-103 
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    ISSN: 1572-9567
    Keywords: cesium vapor ; lithium vapor ; sodium vapor ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New experimental data were obtained on transport coefficients of alkali metals in gaseous phase at high temperatures and within the pressure range from about 10 to about 100 kPa: lithium—thermal conductivity, T= 1400–1800 K, and viscosity, T=1600–2000 K; sodium-viscosity, T= 1100–1500 K; and cesiumviscosity, T=900–1250 K. Viscosity of the alkali metal vapors has been measured using a stationary-technique viscometer with an annular gap. Thermal conductivity was measured by the method of the nonstationary monotonous heating. Experimental data were used as a basis for computing effective atomatom and atom-molecule collision cross section, the values obtained from data on viscosity being in good agreement with those derived from thermal conductivity data. In the case of lithium, the atom-atom cross sections yielded by experiments are fairly consistent with the results of calculations with exact formulae of kinetic theory on the basis of quantum-mechanical potential curves for atom-atom interactions. This has enabled the authors to compile consistent tables of viscosities and thermal conductivities for lithium in a gaseous phase within the temperature range from 800 to 2500 K and pressures from 0.5 to 800 kPa, including the saturation curve.
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    Viscosity measurements of molten LiCl in the temperature range 886–1275 K (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 223-230 
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    ISSN: 1572-9567
    Keywords: lithium chloride ; molten salt ; oscillating-cup viscometer ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of molten lithium chloride has been measured with an oscillating-cup viscometer in the temperature range from 886 to 1275 K along the saturation line. Lithium chloride has been proposed as a heat-transfer fluid for high-temperature applications. Previously reported viscosity data for lithium chloride show sizable discrepancies. The accuracy of the present measurements is estimated as ±2.0%.
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    Research on thermophysical properties of fluids at the Grozny Petroleum Institute (USSR) (1990)
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    International journal of thermophysics 11 (1990), S. 239-250 
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    ISSN: 1572-9567
    Keywords: density ; hydrocarbons ; petroleum products ; specific heat ; surface tension ; thermal conductivity ; viscosity
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    Notes: Abstract A brief survey is presented of the thermophysical properties of petroleum, petroleum products, hydrocarbons, and their mixtures and of other working fluids that are being investigated at the Grozny Petroleum Institute in the USSR. The properties include density, specific heat, surface tension, thermal conductivity, and viscosity. A list of references with the relevant information is included.
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    The initial density dependence of transport properties: Noble gases (1991)
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    International journal of thermophysics 12 (1991), S. 27-42 
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    ISSN: 1572-9567
    Keywords: noble gases ; second transport virial coefficients ; thermal conductivity ; viscosity
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    Notes: Abstract The usual procedure that the transport properties at atmospheric pressure are identified with values in the limit of zero density cannot be accepted for all reduced temperatures T *. It is shown in the framework of the Rainwater-Friend theory for noble gases, as a good example, that for T *〈1 the effect of the initial density dependence has different signs for viscosity and thermal conductivity and amounts to a few percent, when data at atmospheric pressure are compared with zero-density values. An improved representation of the monomer-dimer contribution to the second transport virial coefficients of the Rainwater-Friend theory is presented in the paper. This is based, among others, on the author's own experimental data of the initial density dependence of viscosity of polytomic gases.
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    Viscosity of saturated liquid fluorocarbon refrigerants from 273 to 353 K (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 105-117 
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    ISSN: 1572-9567
    Keywords: capillary viscometer ; fluorocarbons ; refrigerants ; viscosity
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    Topics: Physics
    Notes: Abstract Viscosity measurements were carried out on saturated liquid fluorocarbon refrigerants using an improved capillary viscometer for 11 kinds of fluorocarbon refrigerants; CCl3F (R11), CCl2F2 (R12), CHClF2 (R22), CBrF3 (R13B1), CH3CHF2 (R152a), CCl2FCClF2 (R113), CHCl2CF3 (R123), CHClFCClF2 (R123a), CH3CF3 (R143a), CClF2CCl2F2 (R114), and CH2FCF3 (R134a), in the temperature range from 273 to 353 K. An equation is given to represent the viscosity as a function of temperature.
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    Initial density dependence of experimental viscosities and of calculated diffusion coefficients of the binary vapor mixtures methanol-benzene and methanol-cyclohexane (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 469-490 
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    ISSN: 1572-9567
    Keywords: binary diffusion coefficient ; gas mixtures ; methanol-benzene ; methanol-cyclohexane ; viscosity
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    Topics: Physics
    Notes: Abstract The paper reports experimental results for the viscosity of the vapor mixtures methanol-benzene (five mole fractions with densities up to 1.5kg·m−3 and 0.022 mol·L −1) and methanol-cyclohexane (four mole fractions with densities up to 1.9kg·m−3 and 0.026 mol·L −1). In analogy to the pure components, the measurements on the mixtures were carried out with an oscillating-disk viscometer with small gaps, completely made of quartz, beginning as near as possible to room temperature and continuing to a maximum temperature of 630 K. A first evaluation by means of the Chapman-Enskog theory of dilute gases has shown differences in the resulting values of the interaction viscosity η ij (0) in the limit of zero density exceeding the experimental errors. Consistent results were obtained by taking into account the initial density dependence of the viscosity within the framework of the modified Enskog theory for gaseous mixtures. The values of η ij (0) were also used to estimate binary diffusion coefficients of the mixtures.
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    Correlation of high-pressure thermal conductivity, viscosity, and diffusion coefficients for n-alkanes (1990)
    Springer
    International journal of thermophysics 11 (1990), S. 863-873 
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    ISSN: 1572-9567
    Keywords: diffusion ; hard-sphere theory ; n-alkanes ; thermal conductivity ; viscosity
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    Topics: Physics
    Notes: Abstract Thermal conductivity, viscosity, and self-diffusion coefficient data for liquid n-alkanes are satisfactorily correlated simultaneously by a method based on the hard-sphere theory of transport properties. Universal curves are developed for the reduced transport properties λ *, η *, and D * as a function of the reduced volume. A consistent set of equations is derived for the characteristic volume and for the parameters R λ, R η, and R D, introduced to account for the nonsphericity and roughness of the molecules. The temperature range of the above scheme extends from 110 to 370 K, and the pressure range up to 650 MPa.
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    Accurate transport properties and second virial coefficients for helium based on a state-of-the art interatomic potential (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 837-854 
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    ISSN: 1572-9567
    Keywords: diffusion ; helium ; thermal conductivity ; thermal diffusion ; transport properties ; virials ; viscosity
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    Topics: Physics
    Notes: Abstract Second virial coefficients and transport properties of helium are presented based on a state-of-the-art interatomic potential which was constructed with the use of a multiproperty fit. The experimental potential employed to produce these properties accurately reproduces a wide range of bulk and microscopic data and agrees well with ab initio calculations which were not available at the time of its construction. Virial coefficients of 3He and 4He are presented from 2 to 600 K, and transport properties of pure 3He and 4He gases and 3He-4He mixtures are presented from 5 to 6000 K.
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    Viscosities of nonelectrolyte liquid mixtures. I. binary mixtures containing p-dioxane (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 251-267 
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    ISSN: 1572-9567
    Keywords: activation energy ; aromatic hydrocarbons ; chloroalkanes ; p-dioxane ; molecular interactions ; viscosity
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    Notes: Abstract Viscosity measurements are reported for p-dioxans with cyclohexane, n-hexane, benzene, toluene, carbon tetrachloride, tetrachloroethane, chloroform, pentachloroethane, and ethyl acetate at 303.15 K. Excess Gibbs energies of activation δG *E of viscous flow have been calculated with Eyring's theory of absolute reaction rates. The deviations of the viscosities from a linear dependence on the mole fraction and values of δG *E for binary mixtures have been explained in terms of molecular interactions between unlike pairs. The Prigogine-Flory-Patterson theory has been used to estimate the excess viscosity, δ ln η, and corresponding enthalpy ln η H, entropy ln η S, and free volume ln η v terms for binary mixtures of p-dioxane with cyclohexane, n-hexane, benzene, toluene, carbon tetrachloride, and chloroform. Estimates of excess viscosities from this theory for p-dioxane with benzene, toluene, and carbon tetrachloride are good, while for the other three mixtures they are poor. The local-composition thermodynamic model of Wei and Rowley estimates the excess viscosity quite well even for p-dioxane mixtures with cyclohexane and n-hexane.
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    Correlation and prediction of dense fluid transport coefficients. V. Aromatic hydrocarbons (1992)
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    International journal of thermophysics 13 (1992), S. 895-905 
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    ISSN: 1572-9567
    Keywords: benzene ; diffusion ; ethylbenzene ; hard-sphere theory ; mesitylene ; thermal conductivity ; toluene ; viscosity ; xylene
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    Notes: Abstract A previously described method, based on consideration of hard-sphere theory, is used for the simultaneous correlation of the coefficients of self-diffusion, viscosity, and thermal conductivity for benzene, toluene, o-, m-, and p-xylene, mesitylene, and ethylbenzene in excellent agreement with experiment, over extended temperature and pressure ranges. Values are given for the roughness factors R D , R η, and R λ, and the characteristic volume, V 0, is expressed as a function of both carbon number and temperature.
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    Measurements of the viscosity of toluene + mesitylene mixtures at pressures up to 55 MPa (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 791-800 
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    ISSN: 1572-9567
    Keywords: high pressure ; mesitylene ; mixtures ; toluene ; viscosity
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    Notes: Abstract New absolute measurements of the viscosity of mesitylene and binary mixtures of toluene + mesitylene are presented. The measurements were performed in a vibrating-wire instrument and cover a temperature range of 295–330 K and pressures up to 55 MPa. The concentrations studied were 40 and 70%, by weight, of toluene. The overall uncertainty in the reported data is estimated to be ±0.5%. A recently extended semiempirical scheme for the prediction of the viscosity of mixtures from the pure components is used to predict successfully the viscosity of these mixtures, as a function of composition, temperature, and pressure.
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    Surface-tension effects in suspended-level capillary viscometers (1991)
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    International journal of thermophysics 12 (1991), S. 1013-1028 
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    Keywords: capillary viscometers ; Ostwald viscometer ; surface tension ; Ubbelohde viscometer ; viscosity
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    Notes: Abstract The results of an experimental study of surface-tension effects in kinematic capillary viscometers of the suspended-level type are presented. These results are deduced from a comparison with measurements obtained with a special Ostwald viscometer in which surface-tension effects are negligibly small. It is shown that surface-tension effects in suspended-level viscometers are sensitive to the shape of the capillary exit. Recommendations how to minimize these effects are discussed.
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    Oscillating-cup viscometry over an extended viscosity and temperature range (1993)
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    International journal of thermophysics 14 (1993), S. 777-794 
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    Keywords: hydrocarbons ; molten salts ; oils ; viscosity ; ZrF4
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    Topics: Physics
    Notes: Abstract The viscosity of some ZrF4-based melts is presented and it is demonstrated that it is possible to perform reliable viscosity studies of these highly corrosive melts. Graphite crucibles have been utilized and corrections for the meniscus and the penetration into the crucible have been performed. A general discussion of oscillating-cup viscometry is given and it is shown that the present setup can be used for determination of viscosities in the range from 0.05 to above 500 mPa·s.
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    Argon+carbon dioxide gaseous mixture viscosities and anisotropic pair potential energy functions (1993)
    Springer
    International journal of thermophysics 14 (1993), S. 819-833 
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    ISSN: 1572-9567
    Keywords: argon ; carbon dioxide ; mixtures ; pair potential energy functions ; viscosity
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    Topics: Physics
    Notes: Abstract The viscosities of pure gaseous carbon dioxide and argon+carbon dioxide mixtures have been measured with a capillary flow viscometer. The viscosities are relative to those of argon, in the temperature range 213 to 353 K, and considered accurate to ±0.7%. The pure-component viscosities agree closely with previous measurements. The mixture viscosities are used to calculate interaction viscosities and binary diffusion coefficients, which are compared with previous measurements. Interaction viscosities have been calculated, by use of the Mason-Monchick approximation, from the anisotropic pair potential energy functions for the unlike interaction proposed by Pack and his co-workers and by Hough and Howard. Comparison of these calculated interaction viscosities with those derived from our experiments and the higher-temperature measurements of Hobley, Matthews, and Townsend proves to be a powerful discriminant for the proposed anisotropic potential functions.
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    The viscosity of R32 and R125 at saturation (1993)
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    International journal of thermophysics 14 (1993), S. 1131-1143 
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    ISSN: 1572-9567
    Keywords: refrigerants ; R32 ; R125 ; viscosity
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    Topics: Physics
    Notes: Abstract This paper reports new measurements of the viscosity of R32 and R125, in both the liquid and the vapor phase, over the temperature range 220 to 343 K near the saturation line. The measurements in both liquid and vapor phases have been carried out with a vibrating-wire viscometer calibrated with respect to standard reference values of viscosity. It is estimated that the uncertainty of the present viscosity data is one of 0.5–1%, being limited partly by the accuracy of the available density data. The experimental data have been represented by polynomial functions of temperature for the purposes of interpolation.
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    Measurements of the viscosity of alcohols in the temperature range 290–340 K at pressures up to 30 MPa (1994)
    Springer
    International journal of thermophysics 15 (1994), S. 95-107 
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    Keywords: 1-butanol ; ethanol ; high pressure ; methanol ; 1-propanol ; viscosity ; water
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    Topics: Physics
    Notes: Abstract New measurements of the viscosity of methanol, ethanol, 1-propanol, and 1-butanol are presented. The measurements were performed in a vibrating-wire instrument and cover a temperature range of 290–340 K and pressures up to 30 MPa. The overall uncertainty in the reported data, confirmed by the measurement of the viscosity of water, is ±0.5 %. The high-pressure experimental results were correlated by a Tait-like equation. It was found that the isothermal viscosity data were satisfactorily correlated by such an equation.
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    Measurements of the viscosity of liquid R22, R124, and R125 in the temperature range 273–333 K at pressures up to 17 MPa (1994)
    Springer
    International journal of thermophysics 15 (1994), S. 779-790 
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    ISSN: 1572-9567
    Keywords: high pressure ; liquid ; refrigerants ; R22 ; R124 ; R125 ; vibrating-wire ; technique ; viscosity
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Viscosity masurements of refrigerants R22, R124, and R125 in the liquid phase have been performed in the temperature range 273–333 K and at pressures up to about 17 MPa. A vibrating-wire instrument has been employed. The overall uncertainty of the experimental values is estimated to be ±0.5%. The experimental data have been represented by polynomial functions of temperature and pressure for the purposes of interpolation.
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    Viscoelastic and rheological behavior of concentrated colloidal suspensions (1994)
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    International journal of thermophysics 15 (1994), S. 1179-1188 
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    ISSN: 1572-9567
    Keywords: concentrated colloids ; rheology ; viscoelasticity ; viscosity
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    Topics: Physics
    Notes: Abstract Molecular approaches are discussed to the density (ϕ), viscoeleastic (ω), and rheological (γ) behavior of the viscosityη(ϕ,ω,γ) of concentrated colloidal suspensions with 0.3 〈ϕ 〈 0.6, whereϕ, is the volume fraction,ω the applied frequency, and ; the shear rate. These theories are based on the calculation of the pair distribution functionP 2(r,ω,γ), wherer is the relative position of a pair of colloidal particles. The linear viscoelastic behaviorη(ϕ,ω,γ=0) follows from an equation forP 2(r,ω,γ) derived from the Smoluchowski equation for smallϕ, generalized to largeϕ by introducing the spatial ordering and (cage) diffusion typical for concentrated suspensions. The rheological behaviorη(ϕ,ω,γ=0) follows from an equation forP 2(r,γ) of a dense hard-sphere fluid derived from the Liouville equation. This leads to a hard-sphere viscosityηηhs(ϕ,γ) which yields the colloidal oneη(ϕ,γ) by the scaling relationη(ϕ,γ)η 0=ηηhs(η,γ)η B, whereη 0 is the solvent viscosity.η B is the dilute hard-sphere (Boltzmann ) viscosity and theγ's are appropriately scaled,η(ϕ,ω) andη(ϕ,γ) agree well with experiment. A unified theore forη(ϕ,ω,γ) is clearly needed and pursued.
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    Status of the round robin on the transport properties of R134a (1995)
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    International journal of thermophysics 16 (1995), S. 63-78 
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    Keywords: R134a ; dilute gas ; refrigerant ; saturation properties ; 1,1,1,2-tetrafluoroethane ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
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    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
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    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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    Keywords: critical dynamics ; micellar solution ; shear effects ; spinodal decomposition ; viscosity
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    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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    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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    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
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    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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    Shear viscosity of the binary liquid mixture 3-methylpentane + nitroethane near the consolute point (1982)
    Springer
    International journal of thermophysics 3 (1982), S. 365-369 
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    ISSN: 1572-9567
    Keywords: critical region ; methylpentane ; mixtures ; nitroethane ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Shear viscosity measurements of a mixture of 3-methylpentane and nitroethane at the critical concentration are presented in the temperature range 0.005 K⩽T–T c⩽13.93 K, where T c is the consolute or critical temperature. The data agree with earlier measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00502350
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  • 94
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00502393
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  • 95
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500154
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  • 96
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    Prediction of Fluid Mixture Transport Properties by Molecular Dynamics (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 437-448 
    Details
    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%.
    Type of Medium: Electronic Resource
    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.
    Type of Medium: Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00503840
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    The dilute-gas properties of some systems containing CO2 (1987)
    Springer
    International journal of thermophysics 8 (1987), S. 335-350 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00503946
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  • 100
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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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022626503214
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