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  • Articles  (133)
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  • viscosity  (133)
  • Springer  (133)
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  • 2000-2004  (24)
  • 1995-1999  (109)
  • Physics  (92)
  • Chemistry and Pharmacology  (54)
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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Hydrogen Bonding of Carboxylic Acids in Aqueous Solutions—UV Spectroscopy, Viscosity, and Molecular Simulation of Acetic Acid (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 935-948 
    Details
    ISSN: 1572-8927
    Keywords: Hydrogen bonding ; carboxylic acids ; acetic acid ; UV spectroscopy ; viscosity ; molecular simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The UV spectra of aqueous acetic acid solutions up to 2M were investigated. At these wavelengths, the carboxylic acids exhibit an absorption peak, attributed to the C=O group, which shifts when hydrogen bonds are formed.. The measured spectra were best fitted to several bands, either of Gaussian or Lorentzian shape, which can be explained as several types of structural units formed by hydrogen bonds established between acetic acid and water molecules and between acetic acid molecules themselves. Molecular dynamics simulation of these mixtures was also performed, confirming the occurrence of several types of hydrogen bonds and showing the presence of dimers at higher concentrations. The viscosity and density of these solutions were also measured at different concentrations and temperatures. These results give a more complete picture of the hydrogen bond network of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022615329598
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  • 6
    Electronic Resource
    Electronic Resource
    Solvent Effects on the Electrochemical Behavior of Iron(III) Schiff Base Complex (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 979-991 
    Details
    ISSN: 1572-8927
    Keywords: Electrochemistry ; iron(III) ; Schiff base complex ; solvents effects ; acceptor–donor interactions ; dielectric constant ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electrochemical reduction of FeIIILCl where L is a Schiff base has been investigated in various aprotic solvents. From a plot of the half wave potential E 1/2 for the reduction of these complexes vs. E 1/2 for the oxidation of ferrocene, the solvent–solute interactions were studied: the E 1/2 variation is found to be a function of Lewis-type acceptor–donor interactions. The diffusion coefficients D in the different solvents were also been determined by linear sweep voltammetry. The variation of D is discussed in terms of viscosity and dielectric constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022696120029
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  • 7
    Electronic Resource
    Electronic Resource
    A Viscometric and Conductometric Investigation of the Micellar and Solution Properties of Two-Headed Surfactant Systems, the Disodium 4-Alkyl-3-sulfonatosuccinates (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 217-233 
    Details
    ISSN: 1572-8927
    Keywords: Two-Headed surfactants ; critical micelle concentration ; degree of counterion dissociation ; aggregation number ; conductance ; viscosity ; B-coefficients ; thermodynamic parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A family of two-headed surfactants, the disodium 4-alkyl-3-sulfonatosuccinates, has been prepared by reacting maleic anhydride with the appropriate chain-length alcohol and subsequent addition of sodium bisulfite to the corresponding monoester. The properties of the micelles formed by these compounds in aqueous solution (aggregation numbers, degrees of counterion binding, and the cmc values) have been investigated as a function of temperature and surfactant chain length using viscosity, density, and conductance measurements. The critical micelle concentrations (cmc's) and the aggregation numbers appear to indicate that, in agreement with the earlier literature on other two-headed surfactants systems, these amphiphiles have higher cmc and lower aggregation numbers when compared to single-headed surfactants of comparable chain length. In addition, viscosity B coefficients and the thermodynamic parameters of activation of viscous flow have been determined. These results are interpreted in terms of the structure-making or -breaking properties of the surfactant amphiphiles below the cmc region. Finally, the thermodynamic properties of micelle formation have been estimated from the dependence of the cmc on the absolute temperature according to the charged pseudo-phase separation model of micelle formation. All these results are discussed in terms of how the addition of the second charged surfactant headgroup alters the micellar and solution properties of two-headed surfactants vs. their single-headed counterparts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022684101316
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  • 8
    Electronic Resource
    Electronic Resource
    Measurement and Correlation of Viscosities, Densities, and Water Activities for the System Poly(propylene glycol) + MgSO4 + H2O at 25°C (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 663-673 
    Details
    ISSN: 1572-8927
    Keywords: Poly(propylene glycol) ; magnesium sulfate ; viscosity ; density ; water activity ; aqueous solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Viscosities, densities, and water activities for binary and ternary systems of poly(propylene glycol) 425 + H2O and poly(propylene glycol) 425 + MgSO4 + H2O have been measured at 25°C. From density and viscosity measurements, excess volumes and excess viscosities of the binary poly(propylene glycol) 425 + H2O, over the entire composition range, were obtained and correlated by means of a Redlich–Kister type equation. Viscosity, density. and water activity data for ternary system of poly(propylene glycol) 425 + MgSO4 + H2O were correlated by using a semiempirical equation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022650025229
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  • 9
    Electronic Resource
    Electronic Resource
    Viscosities of n-Alkyl Chlorides from 15 to 80°C (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 761-770 
    Details
    ISSN: 1572-8927
    Keywords: n-Alkyl chlorides ; viscosity ; molar volume ; energy ; Hildebrand's equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The viscosities of n-alkyl chlorides from pentyl to hexadecyl chloride were determined at temperatures between 15 to 80°C at 5°C intervals. The intrinsic volumes of the n-alkyl chlorides were determined by extrapolation of the plot of fluidity against molar volume to zero fluidity. Plots of the logarithm of viscosity vs. reciprocal absolute temperature were almost linear. The energies of activation for viscous flow for the n-alkyl chlorides were calculated and found to increase with increase in chain length. The fluidities, Φ, of the n-alkyl chlorides were found to obey the modified form of Hildebrand's equation.Φ = D[(V-Vo/Vo]\exp(-EB/RT) where D is a constant, V and V o are the molar volume and the intrinsic molar volume, respectively, and E B is an energy term corresponding to the energy required for disrupting the association of the molecules. The activation energy for viscous flow consists of the sum of the energy required for the expansion of the void volume and the energy required to overcome intermolecular interactions. These energies were calculated and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022661708411
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  • 10
    Electronic Resource
    Electronic Resource
    Water—Trifluoroethanol Mixtures: Some Physicochemical Properties (2000)
    Springer
    Journal of solution chemistry 29 (2000), S. 1159-1172 
    Details
    ISSN: 1572-8927
    Keywords: fluoro-alcohol ; mixtures ; density ; viscosity ; relative permittivity ; surface tension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The-physicochemical properties of water—2,2,2 trifluoroethanol mixtures havebeen investigated, at 25°C, by density, viscosity, surface tension, and relativepermittivity. An analysis based on the Kirkwood theory for the dielectric polarizationof mixtures has been performed and the gκ correlation factor has been relatedto the occurrence of hydrogen bonding networks. Data on the above systemhave been analyzed and compared to data on water—ethanol mixtures, to obtaininformation on the role that partial fluorination plays in the interactions of alcoholswith water molecules. As inferred from excess properties, nonideality contributionsare smaller than in the corresponding water—ethanol solutions. Accordingly,the extension of hydrogen bond networks and/or van der Waals contributions tothe overall system stability are less significant than in simple alcohols.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005147318013
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  • 11
    Electronic Resource
    Electronic Resource
    Hartley–Crank Equations for Coupled Diffusion in Concentrated Mixed Electrolyte Solutions. The CaCl2 + HCl + H2O System (1999)
    Springer
    Journal of solution chemistry 28 (1999), S. 341-366 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficients ; aqueous CaCl2 + HCl solutions ; coupled diffusion ; Hartley–Crank theory ; hydration ; ionic mobilities ; mixed electrolyte diffusion ; Nernst—Planck equations ; Pitzer equations ; ternary diffusion ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nernst—Planck equations and ionic conductivities are used to calculate accurate limiting interdiffusion coefficients D ik o for mixed electrolyte solutions. The electrostatic mechanism for coupled electrolyte diffusion is investigated by calculating the electrostatic contribution to each D ik o coefficient to give the flux of each electrolyte driven by the electric field, which is generated by the migration of ions of different mobilities. Ternary diffusion coefficients are measured for dilute aqueous K2SO4 + KOH and Li2SO4 + LiOH solutions. Because of the different mobilities of K+ and Li+ ions relative to SO 4 2− ions, diffusing K2SO4 drives cocurrent flows of KOH, but diffusing Li2SO4 drives counterflows of LiOH. To describe coupled diffusion in concentrated mixed electrolyte solutions, the Hartley–Crank theory is used to correct the limiting D ik o coefficients for nonideal solution behavior, viscosity changes, ionic hydration, and the zero-volume flow constraint. Diffusion coefficients predicted for concentrated aqueous CaCl2 + HCl solutions are compared with recently reported data. The large amount of HCl cotransported by the diffusing CaCl2 is attributed to the “salting out” of HCl by CaCl2 and to the migration of H+ ions in the diffusion-induced electric field, which slows down the Cl− ions and speeds up the less-mobile Ca2+ ions to maintain electroneutrality along the CaCl2 gradient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022603827760
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  • 12
    Electronic Resource
    Electronic Resource
    Density and viscosity studies of poly(ethylene-oxide) alkyl alcohols (1996)
    Springer
    Journal of solution chemistry 25 (1996), S. 757-772 
    Details
    ISSN: 1572-8927
    Keywords: Surfactants ; poly(ethylenoxide)alkyl alcohols ; density ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Density and viscosity of binary systems water-nonionic surfactants poly(ethylen-oxide) alkyl alcohols type, [CnH2n+1(OCH2CH2)mOH, CnEm], have been studied. The partial molar volumes in the dilute solution range and the viscosity B-coefficients were calculated. The nonionic surfactants partial molar volumes were compared with those of ethylene glycol and poly(ethylenglycol) (PEG). The comparison shows that the ethoxy unit volume, $$\bar V^O $$ (OCH2CH2), seems to be independent of the particular system. The consequences of this are discussed. A model for interpreting the experimental B values has been proposed. The model treats the macroscopic viscosity as the superimposition of different local effects. The following surfactants have been considered: C5E1, C5E2, C6E1, C6E2, C6E3, C6E4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973783
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  • 13
    Electronic Resource
    Electronic Resource
    Density, viscosity, and surface tension of binary liquid systems: Ethanoic acid, propanoic acid, and butanoic acid with nitrobenzene (1996)
    Springer
    Journal of solution chemistry 25 (1996), S. 905-917 
    Details
    ISSN: 1572-8927
    Keywords: Excess molar volume ; viscosity ; activation energy ; surface tension ; ethanoic acid ; propanoic acid ; butanoic acid ; nitrobenzene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Density, viscosity, and surface tension of three binary liquid systems: ethanoic acid+nitrobenzene, propanoic acid+nitrobenzene, and butanoic acid+nitrobenzene have been determined at 25, 35, and 45°C, over the whole composition range. The excess molar volumes, viscosities, Gibbs energies for the activation of flow, and surface tension were evaluated and fitted to a Redlich-Kister type of equation. The Grunberg-Nissan parameter d was also calculated. Binary viscosity data were fitted to the models of McAllister, Heric, Krishnan, and Laddha, Auslander, and Teja and Rice. Surface tension data were fitted to the models of Zihao and Jufu, Rice, and Teja, and an empirical two-constant model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00972581
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  • 14
    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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  • 15
    Electronic Resource
    Electronic Resource
    Thermally Stimulated Processes in a Liquid Crystal Polymer (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 1167-1173 
    Details
    ISSN: 1572-8943
    Keywords: charge carriers ; depolarization rate ; liquid crystalline polyester ; molecular realignment ; thermal depolarization current ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Measurement of voltage-induced thermal depolarization current and calculation of the rate of depolarization as well as the parameters of drift mobility and conductivity of charge carriers for melt-extruded neat unreinforced grade A950 VECTRA® resin - a wholly aromatic copolyester - strongly suggest that an irreversible minor transition centered around 65°C is the primary thermal process related to molecular realignment. Changes in capacitance values with temperature also show this to be the most active temperature region. A major depolarization peak at 100°C having the characteristics of a Tg cannot be justified as due to glass transition but likely to result from molecular motions involving long range intermolecular order. The interpretation for both transitions can be supported by the mechanical response of this polymer. An important outcome of this work is the assertion that contrary to current thinking, it is the number of charge carriers and not viscosity alone that will have to be considered in future development of fast response liquid crystal displays along with the development of newer liquid crystal polymer structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010165214203
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  • 16
    Electronic Resource
    Electronic Resource
    Transport coefficients of air, argon-air, nitrogen-air, and oxygen-air plasmas (1995)
    Springer
    Plasma chemistry and plasma processing 15 (1995), S. 279-307 
    Details
    ISSN: 1572-8986
    Keywords: Transport coefficients ; transport properties ; viscosity ; thermal conductivity ; electrical conductivity ; diffusion coefficient ; Chapman-Etskog method ; air ; argon ; nitrogen ; oxygen ; plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Calculated values of the viscosity, thermal conductivity and electrical conductivity of air and mixtures of air and argon, air and nitrogen, and air and oxygen at high temperatures are presented. In addition, combined ordinary, pressure, and thermal diffusion coefficients are given for the gas mixtures. The calculations, which assione local thermodynamic equilibrium, are performed for atmospheric pressure plasmas in the temperature range from 300 to 30,000 K. The results for air plasmas are compared with those of published theoretical and experimental studies. Significant discrepancies are found with the other theoretical studies; these are attributed to differences in the collision integrals used in calculating the transport coefficients. A number of the collision integrals used here are significantly more accurate than values used previously, resulting in more reliable values of the transport coefficients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01459700
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  • 17
    Electronic Resource
    Electronic Resource
    Critical analysis of viscosity data of thermal argon plasmas at atmospheric pressure (1996)
    Springer
    Plasma chemistry and plasma processing 16 (1996), S. 635-650 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; argon ; transport properties ; viscosity ; interatomic potentials ; collision integrals ; calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Reliable values of the viscosity in thermal argon plasmas are most important for our understanding of the momentum transfer and for realistic modeling of various plasma applications. Despite numerous attempts to determine reliable viscosity values over the last three decades, discrepancies still exist among the data reported by different authors. In this paper, a critical analysis is undertaken of calculated and experimental data of the argon viscosity based on recent publications. Our recalculation of viscosities in thermal argon plasmas are performed by using Lennard-Jones, Morse, Aziz, and exponential repulsive potentials for Ar-Ar atom interactions in different temperature ranges from 300 to 20,000 K. The contributions of elastic collisions of e-Ar, e-Ar+, and Ar+-Ar, as well as charge exchange of Ar+-Ar, to the viscosity become important with increasing temperature and degree of ionization in argon plasmas. Based on a critical analysis and recalculations, improved values of the argon viscosity are recommended, covering temperatures from 300 to 20,000 K. Polynomial expressions have been developed for calculating argon viscosities, which will be useful for numerical work and other applications of thermal argon plasmas at atmospheric pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447012
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  • 18
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    Electronic Resource
    Transport Coefficients of Hydrogen and Argon–Hydrogen Plasmas (2000)
    Springer
    Plasma chemistry and plasma processing 20 (2000), S. 279-297 
    Details
    ISSN: 1572-8986
    Keywords: Transport coefficients ; transport properties ; viscosity ; thermal conductivity ; electrical conductivity ; diffusion coefficient ; Chapman–Enskog method ; hydrogen ; argon ; plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Calculated values of the viscosity, thermal conductivity, and electrical conductivity of hydrogen and mixtures of argon and hydrogen at high temperatures are presented. Combined ordinary, pressure, temperature, and electric field diffusion coefficients are also given for the mixtures. The calculations, which assume local thermodynamic equilibrium, are performed for atmospheric pressure plasmas in the temperature range from 300 to 30,000 K. The results are compared with those of previously published studies. Generally, the agreement is reasonable; those discrepancies that exist are attributed to the improved values of some of the collision integrals used here in calculating the transport coefficients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007099926249
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  • 19
    Electronic Resource
    Electronic Resource
    Fabrication of PbTiO3 Ceramic Fibers by Sol-Gel Processing (1997)
    Springer
    Journal of sol gel science and technology 9 (1997), S. 71-84 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel processing ; fiber ; PbTiO3 ; perovskite ; preferred orientation ; Pb-Ti double alkoxide ; spinnability ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The sol-gel processing was applied to the fabrication of PbTiO3 fibers. Pb(CH3COO)2 · 3H2O and Ti(OC3H $$_7^i $$ )4 were refluxed with stirring in 2-methoxyethanol to form Pb-methoxyethoxide and Ti-methoxyethoxide, respectively, followed by mixing with stirring in 2-methoxyethanol to form Pb-Ti double alkoxide. The hydrolysis and polycondensation reaction of this double alkoxide gave polymerized products, and as a result the viscosity of the solution increased, suggesting that linear polymers were produced through the hydrolysis and polycondensation reaction. Homogeneous PbTiO3 gel fibers were drawn from the spinnable viscous solutions, which were well-crystallized into perovskite type PbTiO3 at 650°C. The heat-treated fibers were a few centimeters long and from 10 to 100 μm in diameter. The fiber was made up of extremely uniform grains. Electron diffraction revealed a preferred growth of (101) planes along the fiber axis, which might be due to the linear molecular characteristics of the alkoxide.
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    URL: http://dx.doi.org/10.1023/A:1026464424392
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  • 20
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    Electronic Resource
    Fabrication of PbTiO3 ceramic fibers by sol-gel processing (1997)
    Springer
    Journal of sol gel science and technology 9 (1997), S. 71-84 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel processing ; fiber ; PbTiO3 ; perovskite ; preferred orientation ; Pb−Ti double alkoxide ; spinnability ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The sol-gel processing was applied to the fabrication of PbTiO3 fibers. Pb(CH3COO)2·3H2O and Ti(OC3H 7 i )4 were refluxed with stirring in 2-methoxyethanol to form Pb-methoxyethoxide and Ti-methoxyethoxide, respectively, followed by mixing with stirring in 2-methoxyethanol to form Pb−Ti double alkoxide. The hydrolysis and polycondensation reaction of this double alkoxide gave polymerized products, and as a result the viscosity of the solution increased, suggesting that linear polymers were produced through the hydrolysis and polycondensation reaction. Homogeneous PbTiO3 gel fibers were drawn from the spinnable viscous solutions, which were wellcrystallized into perovskite type PbTiO3 at 650°C. The heat-treated fibers were a few centimeters long and from 10 to 100 μm in diameter. The fiber was made up of extremely uniform grains. Electron diffraction revealed a preferred growth of (101) planes along the fiber axis, which might be due to the linear molecular characteristics of the alkoxide.
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    Environmental constraints in the study of flexible segments of proteins (1998)
    Springer
    Journal of biomolecular NMR 11 (1998), S. 415-422 
    Details
    ISSN: 1573-5001
    Keywords: BPTI ; cryoprotective mixtures ; flexibility ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The structural problem posed by ill-defined segments in protein structures is similar to those encountered in the study of most peptide hormones, with terminal tracts resembling linear peptides and loops resembling cyclic peptides. The conformational preferences of short linear peptides in solution can be influenced by the use of solvent mixtures of viscosity higher than that of pure water but comparable to that of cytoplasm. In order to check whether it is possible to use these media in the structural study of proteins, we undertook an exploratory study on BPTI in a mixture of dimethylsulfoxide and water. The complete assignment of BPTI in an 80:20 (by volume) DMSO-d 6/water cryomixture at two temperatures showed that all resonances parallel those in water, hinting at the persistence of the correct protein architecture, which is also confirmed by NOESY experiments. In addition to the NOEs present in the aqueous solution it was possible to detect numerous new cross peaks, in particular from residues belonging to the less-defined regions. The new cross peaks do not originate from spin diffusion and are consistent with the best NMR structure and with the X-ray structures of BPTI.
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    URL: http://dx.doi.org/10.1023/A:1008223003135
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    Preparation of Lead Zirconate Titanate Ceramic Fibers by Sol-Gel Method (2000)
    Springer
    Journal of sol gel science and technology 18 (2000), S. 235-247 
    Details
    ISSN: 1573-4846
    Keywords: lead zirconate titanate ; ceramic fibers ; two-stage heat treatment ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract PZT fibers with the nominal composition of Pb(Zr0.53Ti0.47)O x have been successfully drawn by the sol-gel techniques. Ti(O·i–C3H7)4, Zr(O·n–C4H9)4, and Pb(O2C8H15)2 were used as the starting materials. The rheological conditions for continuous gel fiber drawing were determined. Thermal and microstructural evolutions of gel fibers were investigated by X-ray diffraction and Fourier-transform infrared spectroscopy. Perovskite crystalline fibers without breakage were obtained by a two-stage heat treatment on the gel fibers up to 600°C in air. Bending strength of the fibers decreases with the increase of the fiber diameter and is ranged from 10 to 30 MPa.
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    URL: http://dx.doi.org/10.1023/A:1008748023345
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    Sintering Aerogels (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 937-943 
    Details
    ISSN: 1573-4846
    Keywords: sintering ; aerogel ; pore size distribution ; viscosity ; characterization (of aerogels)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Studies of the densification kinetics and structural evolution of non-crystalline aerogels during sintering are examined in light of theory. In most respects, the theory of viscous sintering is capable of quantitatively accounting for the experimentally observed behavior, as long as the initial pore size distribution is known. Unfortunately, it is difficult to obtain adequate structural information; in particular, measurements using nitrogen desorption and thermoporometry often erroneously indicate the presence of macroporosity. Some authors have claimed that large pores contract more quickly than small pores during sintering; under certain circumstances this is predicted by the theory.
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    URL: http://dx.doi.org/10.1023/A:1008687610326
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    Viscosity and structure of Ormosil solutions (1995)
    Springer
    Journal of sol gel science and technology 5 (1995), S. 83-92 
    Details
    ISSN: 1573-4846
    Keywords: organic-inorganic hybrids ; ormosils ; viscosity ; sol-to-gel transition ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract PDMS (polydimethylsiloxane)/TEOS (tetraethoxysilane) system Ormosils (organically modified silicates) can be rubbery or rigid, depending on their chemical composition and processing conditions. In order to determine the relationship between the viscosity and the structure of the Ormosil solutions through the sol-to-gel transition, five kinds of sols (three levels of PDMS, three levels of H2O) were prepared with refluxing. Viscosities were measured using an oscillation method with a cone-and-plate type apparatus. Liquid state 29Si-NMR analyses were made to obtain structural information of the solution. The composition of the starting solution affected the sol-to-gel transition process. The degree of hydrolysis, depending upon the H2O content, controlled the reaction rate and structure of the polymer. Addition of PDMS also contributed to the acceleration of the sol-to-gel transition due to larger PDMS copolymerizing units.
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    URL: http://dx.doi.org/10.1007/BF00487724
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    High Temperature Behavior of a Gel-Derived SiOC Glass: Elasticity and Viscosity (1999)
    Springer
    Journal of sol gel science and technology 14 (1999), S. 87-94 
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    ISSN: 1573-4846
    Keywords: oxycarbide glasses ; sol-gel ; mechanical properties ; elasticity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The high temperature behavior of a sol-gel derived silicon oxycarbide glass containing 12 at.% carbon has been characterized by means of creep and in-situ ultrasonic echography measurements. Temperature induced changes include structural relaxation and densification from 1000 to 1200°C, and crystallization to form a fine and homogeneous β-SiC/glass-matrix nanocomposite with 2.5 nm large crystals above 1200°C. Young's modulus measurements clearly reveal a consolidation of the material upon annealing below 1200°C. Crystallization is almost complete after few hours at 1300°C and results in a significant increase in Young's modulus. The viscosity of the oxycarbide glass is much higher than that of fused silica, with two orders of magnitude difference at 1200°C, and the glass transition temperature ranges from 1320 to 1370°C.
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    URL: http://dx.doi.org/10.1023/A:1008779915809
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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.
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    URL: http://dx.doi.org/10.1023/A:1009447226786
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    Chitosan functional properties (1997)
    Springer
    Glycoconjugate journal 14 (1997), S. 535-542 
    Details
    ISSN: 1573-4986
    Keywords: chitosan ; squid ; crustacean ; viscosity ; flocculation ; film ; solubility ; functional ; properties ; composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Chitosan is a partially deacetylated polymer of N-acetyl glucosamine. It is essentially a natural, water-soluble, derivative of cellulose with unique properties. Chitosan is usually prepared from chitin (2 acetamido-2-deoxy β-1,4-D-glucan) and chitin has been found in a wide range of natural sources (crustaceans, fungi, insects, annelids, molluscs, coelenterata etc.) However chitosan is only manufactured from crustaceans (crab and crayfish) primarily because a large amount of the crustacean exoskeleton is available as a by product of food processing. Squid pens (a waste byproduct of New Zealand squid processing) are a novel, renewable source of chitin and chitosan. Squid pens are currently regarded as waste and so the raw material is relatively cheap. This study was intended to assess the functional properties of squid pen chitosan. Chitosan was extracted from squid pens and assessed for composition, rheology, flocculation, film formation and antimicrobial properties. Crustacean chitosans were also assessed for comparison. Squid chitosan was colourless, had a low ash content and had significantly improved thickening and suspending properties. The flocculation capacity of squid chitosan was low in comparison with the crustacean sourced chitosans. However it should be possible to increase the flocculation capacity of squid pen chitosan by decreasing the degree of acetylation. Films made with squid chitosan were more elastic than crustacean chitosan with improved functional properties. This high quality chitosan could prove particularly suitable for medical/analytical applications.
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    URL: http://dx.doi.org/10.1023/A:1018524207224
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    The Application of Malononitriles as Microviscosity Probes in Pharmaceutical Systems (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 380-386 
    Details
    ISSN: 1573-904X
    Keywords: microviscosity ; viscosity ; malononitrile ; diffusion ; fluorescence ; p-(N-dimethylaminocinnamylidene) malononitrile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three molecules were investigated for their ability to distinguish variations in the microviscosity of the surrounding medium. Julolidinemalononitrile (JMN), p-(N-dimethylaminobenzylidene) malononitrile (BMN), and p-(N-dimethylaminocinnamylidene) malononitrile (CMN) were dissolved in media of various micro- and bulk viscosities. The fluorescence intensity of each dissolved probe and the bulk viscosity of each medium were measured. In solutions of low molecular weight substances, where the micro- and bulk viscosities are expected to correspond, the fluorescence behavior of each probe was a function of bulk viscosity and was independent of solution composition. In contrast, in aqueous solutions of methyl-cellulose, the fluorescence behavior of the probes corresponds to microviscosities significantly lower than the measured bulk viscosities. Thus, the probes are useful in resolving the microviscosity from bulk viscosity of neat liquid and solution systems. The sensitivity of the probes to viscosity is in the order JMN 〉 BMN 〉 CMN. Due to its limited water solubility, JMN is not particularly useful for pharmaceutical systems. CMN is the preferred probe for these applications due to its high fluorescence intensity over a large viscosity range.
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    URL: http://dx.doi.org/10.1023/A:1016252518401
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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.
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    Thermophysical Properties of Trehalose and Its Concentrated Aqueous Solutions (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 578-590 
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    ISSN: 1573-904X
    Keywords: trehalose ; phase diagram ; glass transition ; viscosity ; molar volume ; cryoprotection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To address the lack of fundamental thermophysical data for trehalose and its aqueous systems by measuring equilibrium and non-equilibrium properties of such systems. Methods/Results. Differential scanning calorimetry (DSC) and dynamic mechanical analysis were used to measure glass transition temperatures of trehalose and its solutions. X-ray diffractometry was used to verify the structure of amorphous trehalose. Controlled-stress rheometry was used to measure viscosity of several aqueous trehalose systems at ambient and sub-ambient temperatures. Over this temperature range, the density of these solutions was also measured with a vibrating tube densimeter. The equilibrium phase diagram of aqueous trehalose was determined by measuring the solubility and freezing point depression. Conclusions. Our solubility measurements, which have allowed long times for attainment of chemical equilibrium, are substantially different from those reported earlier that used different techniques. Our measurements of the glass transition temperature of trehalose are higher than reported values. A simple model for the glass transition is presented to describe our experimental observations.
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    Nebulization of Fluids of Different Physicochemical Properties with Air-Jet and Ultrasonic Nebulizers (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1682-1688 
    Details
    ISSN: 1573-904X
    Keywords: aerosol ; droplet size ; jet nebulizer ; surface tension ; ultrasonic nebulizer ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Empirical formulae relate the mean size of primary droplets from jet and ultrasonic nebulizers to a fluid's physicochemical properties. Although the size selective “filtering” effects of baffling and evaporation may modify the secondary aerosol produced, this research sought to evaluate whether viscosity and surface tension of nebulized fluids influenced the aerosol's size and output characteristics. Methods. Fluid systems of different surface tension and viscosity (glycerol and propylene glycol solutions [10–50% (v/v)] and a range of silicone fluids [200/0.65 cs– l00cs]) were nebulized in three jet and two ultrasonic nebulizers. Secondary aerosol characteristics were measured with a Malvern 2600C laser diffraction sizer and the nebulization times, residual volumes and percentage outputs were determined. Results. While the droplet size appeared to be inversely proportional to viscosity for jet nebulizers, it was directly proportional to viscosity for ultrasonic nebulizers. Although fluid systems with lower surface tensions generally produced slightly smaller MMDs, the relationship between surface tension and droplet size was complex. The more viscous fluids required longer nebulization times and were associated with increased residual amounts (lower outputs). The ultrasonic nebulizers did not effectively, and were on occasion unable to, nebulize the more viscous fluids. Conclusions. It follows that there are cut-off values for viscosity and/or surface tension above or below which ultrasonic devices fail to operate. Moreover, jet nebulizers generated an aerosol with an optimum respirable output from median-viscosity fluids.
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    Determination of the Viscosity of an Amorphous Drug Using Thermomechanical Analysis (TMA) (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 672-675 
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    ISSN: 1573-904X
    Keywords: viscosity ; glass ; amorphous ; thermomechanical analysis ; TMA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To evaluate thermomechanical analysis (TMA) as a technique for determining the viscosity of amorphous pharmaceutical materials. This property of amorphous drugs and excipients is related to their average rate of molecular mobility and thus to their physical and chemical stability. Methods. Indomethacin was selected as a model amorphous drug whose viscosity has previously been reported in the literature. A Seiko TMA 120C thermomechanical analyzer was utilized in isothermal penetration mode to determine the viscosity of the amorphous drug over the maximum possible range of temperatures. Results. Using a cylindrical penetration geometry it was possible to accurately determine the viscosity of amorphous indomethacin samples by TMA over the temperature range from 35 to 75°C. The results were consistent with those reported in the literature using a controlled strain rheometer over the range 44−75°C. The limiting lower experimental temperature for the TMA technique was extended to significantly below the calorimetric glass transition temperature (Tg ≈ 42°C), thus allowing a direct experimental determination of the viscosity at Tg to be made. Conclusions. Thermomechanical analysis can be used to accurately determine the viscosity of amorphous pharmaceutical materials at temperatures near and above their calorimetric glass transition temperatures.
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    Viscosities of poly(N-vinylacetamide) solutions in the presence of salts, urea and guanidine hydrochloride (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 1083-1087 
    Details
    ISSN: 1435-1536
    Keywords: Key words Poly(N-vinylacetamide) ; viscosity ; salting-out ; urea ; guanidine hydrochloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary  In the aqueous solutions of poly(N-vinylacetamide) in the presence of Na2SO4 or (NH4)2SO4, the intrinsic viscosities were small and the Huggins constants were large compared with those in water. Similar but much less effects were observed for NaF. Opposite effects were found, however, for NaSCN. The poor solvent quality of aqueous sulfate solutions was significantly improved by the addition of guanidine hydrochloride to 3 M or higher. Urea was much less effective in improving the solvent quality. The different M28.8neffects observed between urea and GdnHCl may be explained by their different binding affinities to amide group. Solubilization of PNVA flocculates induced by the presence of 0.8 M Na2SO4 took place by adding urea to 1 M, although only small changes were detected in the viscosity behavior accompanying the addition of 1 M urea.
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    Morphology of anomalous polystyrene/ polybutyl acrylate composite particles produced by seeded emulsion polymerization (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 186-189 
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    ISSN: 1435-1536
    Keywords: Key words Composite polymer particle ; seeded emulsion polymerization ; morphology ; phase separation ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Recently, we found that “golf ball”-like polystyrene (PS)/polybutyl acrylate (PBA) composite particles could be produced by seeded emulsion polymerization of butyl acrylate (BA) with PS seed particles. In this article, the effects of the polymerization temperature, BA monomer concentration, and the presence of 1-octanol, which is a good solvent for PBA and a poor solvent for PS in the polymerization, on the morphology was studied.
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    Significance of shear induced structure in surfactants for drag reduction (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 816-823 
    Details
    ISSN: 1435-1536
    Keywords: Key words Drag reduction ; surfactants ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Cationic drag reducing surfactants are suitable means for reducing the energy costs in city district heating and cooling systems. Water used in these systems is usually a treated water, however, the loss of water due to the leakage is often supplied by water from the municipal network and thus the content of ions in the system may increase. That is why the influence of ions present in water and temperature on viscosity curves has been investigated and the effect of both on Shear Induced Structure (SIS) is shown here. We have proved that SIS is not an indispensable condition for the surfactant ability of drag reduction.
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    Measurement of particle diffusion coefficients with high accuracy by dynamic light scattering (1997)
    Springer
    Colloid & polymer science 104 (1997), S. 110-112 
    Details
    ISSN: 1435-1536
    Keywords: Dynamic light scattering ; n-heptane ; particle diffusion ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present a novel optical scattering cell for the measurement of particle diffusion coefficients by dynamic light scattering, which may be utilised for particle size analysis and viscosity measurements. A major feature of the cell is that it allows measurements without knowledge of the refractive index of the dispersing liquid, which facilitates viscosity measurements over an extended range of temperature, where refractive indexes are often not found tabulated. This improvement is achieved by the use of a symmetrical set-up. The light scattering system has been tested by measuring the diffusion coefficient of silica particles in water, where the results showed a total standard deviation of 0.5% including measurements at various angles of incidence. In order to prove the capability of the system for accurate viscosity measurements,n-heptane, where reliable reference values are available, has been investigated in a temperature range of 20°–80°C. The viscosities measured showed a maximum deviation of the mean from the reference values of below 1.0%.
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    A hard sphere microemulsion (1997)
    Springer
    Colloid & polymer science 104 (1997), S. 157-159 
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    ISSN: 1435-1536
    Keywords: Microemulsion ; hardsphere ; compressibility ; diffusion ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present data from an investigation of an oil-in-water nonionic three-component microemulsion system under conditions where spherical droplets with a radius of approximately 80 A form. The structural and dynamic properties of the microemulsion have been studied using a combination of small-angle neutron scattering, static and dynamic light scattering, pulsedgradient NMR self-diffusion and low shear viscosity measurements. We demonstrate that these liquid-like droplets have properties which to a very good approximation mimic those of classical hard sphere suspensions over a large range of volume fractions.
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    The time dependence of chitosan/nonionic surfactant solution viscosity (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 375-383 
    Details
    ISSN: 1435-1536
    Keywords: Chitosan ; nonionic surfactant ; interaction ; viscosity ; time-dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The measurement of the viscosity of semiconcentrated chitosan (0.08–0.14%) solutions in the system with octaethyleneglycolmonon-dodecylether (C12E8) was carried out using Cannon-Fenske capillary viscometer. The interaction was—as expected—very weak, vut when the time dependent hydrodynamic behaviour of the system was considered, the interaction has been established at particular surfactant concentrations. The most significant time dependence is shown in a form of sudden viscosity drop in a region close to and above CMC value of the surfactant, which implied existence of the interaction between chitosan and surfactant. At low surfactant concentrations viscosity values vere constant with increasing surfactant concentration, but solution also showed time dependent decrease in the viscosity which has been connected with well known time dependent viscosity of pure chitosan solution. The viscometry enabled monitoring of the extent of chitosan/surfactant association by establishing the viscosity decrease rate constant. The rate constant was derived from the first order constant of the quadratic polynomial curves used for the approximation of experimental values when these are presented in the form of viscosity-time profiles. This method showed the existence of critical surfactant concentration values (C 1,C 2 andC 3). These values are closely connected with the proposed interaction model which is based on the assumption that spherical surfactant micelles are bound by chitosan molecule.
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    Microphase separation of PEG-modified urethane acrylate and the swelling behavior of its gels (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 1025-1032 
    Details
    ISSN: 1435-1536
    Keywords: PEG-modified urethane acrylate ; microphase separation ; viscosity ; interfacial tension ; gel-swelling ratio ; contact angle measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The viscosity of PEG-modified urethane acrylate (PMUA) showed peculiar behavior in the course of soap-free emulsification. Moreover, the viscosity change with added amounts of water was influenced by the reaction molar ratio of polyethylene glycol (PEG). The rate of increase in viscosity slowed and the ratio of increase in viscosity increased as the reaction molar ratio of PEG increased. This peculiar viscosity behavior was due to the microphase separation between hydrophilic and hydrophobic segments of PMUA, and the orientation of polyoxyethylene groups at O/W interface which influenced droplet size of the soap-free PMUA emulsion. The location of polyoxyethylene groups of this resin at O/W interface was confirmed using the adsorption isotherm measurement of PMUA molecules containing polyoxyethylene groups at water/benzene interface. The microphase separation behavior of PMUA between hydrophilic and hydrophobic segments could apply to the preparation of the PMUA gels containing peculiar structure. PMUA gels were prepared using dioxane (UAG) and the swelling behavior of these gels were compared to that of gels prepared using water (UAHG) in the same medium. In the same medium, the swelling behavior of UAHG gels differed from that of UAG gels because of the difference in the microstructure of gel due to the microphase separation between hydrophilic and hydrophobic segments. This phase separation in the course of gelation in water could be confirmed using contact angle measurement.
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    Phase conditions, hydrodynamic features and salt influence in the polymer-amphiphile interaction for the EHEC/SDS/water system (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 836-847 
    Details
    ISSN: 1435-1536
    Keywords: Ethyl hydroxyethyl cellulose ; sodium dodecyl sulphate ; interaction ; sodium chloride ; viscosity ; equilibrium dialysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Two fractions of ethyl(hydroxy)ethyl cellulose, EHEC, and their interactions with sodium dodecyl sulphate, SDS, have been investigated. The effect of salt on these interactions was explored. The more hydrophobic fraction exhibits a cloud point (CP) of 30°C, and the more hydrophilic fraction has a CP around 65°C. The properties of the systems were studied by means of hydrodynamic (viscosity), equilibrium dialysis and cloud point measurements. Dye solubilization was used to obtain indications of cluster formation on the polymer backbone. The equilibrium dialysis shows a steep binding beginning at a critical surfactant concentration indicating a cooperative effect in the EHEC/SDS/water system. It is found that when the degree of binding is moderate and only 10–20% of the value at saturation, the specific viscosity effects occur and solutions containing high polymer concentrations pass a marked maximum in viscosity. It is shown that the maximum in viscosity and the collcoil interaction, expressed as Huggins constant,k H, appear a composition with the same fractional amount of SDS adsorbed to both EHEC fractions. It was found that the onset of redistribution and increase in viscosity were shifted to higher SDS concentrations, although still below the normal CMC, for the EHEC fraction with a high CP. When small amounts of salt are present in the EHEC/SDS/water solutions, the CP curves develop a pronounced minimum at low SDS concentrations. The redistribution of SDS to the polymers starts immediately in the presence of salt, but the viscosity of the solutions is affected only in a very narrow composition interval.
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    URL: http://dx.doi.org/10.1007/BF00654741
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    Shear-dependent rheological properties of starch/bentonite composite gels (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 567-579 
    Details
    ISSN: 1435-1536
    Keywords: Key words Bentonite ; starch ; rheology ; viscosity ; thixotropy ; amylogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Rheological properties of starch/bentonite gels (5.3–8.2% solids, 0–100% starch) were investigated at shear rates 0.0083–0.33 s-1 (Brookfield viscometer). Prior to these measurements the strain introduced during preparation of the gel was kept as low as possible. Under these conditions six different types of structural units could be identified in the gel: bentonite particles associated in a band-type structure; bands coated with starch polymers; bundles of bands interlaced and enveloped by starch polymers (strands); individual bentonite platelets dispersed in a polymer matrix; starch polymer networks; and swollen granules. A power-law model was fitted to the experimental viscosity data: μapp= Kγ n-1 . In all cases n was found to be less than 0.5. Its value decreased with the ability of the structural components to reorient under applied shear. K was found to be proportional to the compaction and/or entanglement of the structural units. These trends in K and n were further confirmed by the index of thixotropy (IT) and complex modulus of shear elasticity (G * ) measurements.
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    URL: http://dx.doi.org/10.1007/s003960050120
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    Electrophoretic behaviour and viscosities of metal oxides in mixed surfactant systems (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 72-80 
    Details
    ISSN: 1435-1536
    Keywords: Key words Electrokinetics ; mixed surfactant adsorption ; viscosity ; anatase ; alumina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The electrokinetic behavior and viscosity of anatase and alumina in mixed-surfactant solutions were investigated. Sodium dodecylsulfate and nonionic polyoxyethylene ethers were investigated as model surfactants. Pure nonionic surfactants adsorbed on anatase and coated the particles, so that the zeta potential was nearly zero near the critical micelle concentration of surfactant. At higher surfactant concentrations, an increase in the zeta potentials was observed, suggesting a change in the microstructure of the adsorbed layer. Addition of nonionic surfactant to positively charged anatase and alumina with some preadsorbed sodium dodecylsulfate reversed the surface charge of the oxide to negative, indicating enhanced coadsorption of the anionic surfactant. At higher concentrations of the nonionic surfactant, the charge reversed back to positive. Nonionic surfactants did not reverse the surface charge of these oxides in the absence of the anionic surfactant. Coenhanced adsorption of nonionic and anionic surfactants was used to stabilize alumina at the isoelectric point, where neither surfactant adsorbed appreciably on its own. These results suggest a dramatic change in conformation of the surfactant chains in mixed systems. Further explanation and justification of the proposed changes in adsorbed surfactant conformation require spectroscopic evidence.
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    URL: http://dx.doi.org/10.1007/s003960050211
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    Investigation of shear-induced structures in lyotropic mesophases by scattering experiments (1997)
    Springer
    Colloid & polymer science 104 (1997), S. 90-96 
    Details
    ISSN: 1435-1536
    Keywords: Lamellar phase ; hexagonal phase ; vesicle ; viscosity ; neutron scattering ; light scattering ; SALS ; SANS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of shear on the structure of lyotropic liquid crystalline phases was investigated by small angle light and neutron scattering (SALS, SANS). Three different systems were studied involving nonionic and ionic surfactants: a hexagonal phase, a lamellar phase and a defective lamellar phase. Three different regimes are discussed in the hexagonal phase. A polydomain sample with dominating elastic properties, an aligned sample with the rodlike micelles being aligned in flow direction and characterized by a stripe texture. This texture can be disrupted at high shear rates leading to a further decrease of the moduli. Different regimes were also found with the defective lamellar phase. Multilamellar vesicles were formed at intermediate shear rates leading to an increase of viscosity. At higher shear rates these vesicles were destroyed and oriented lamellae were obtained. The lamellae were aligned with the layer normal parallel to the neutral (vorticity) axis. Vesicles were also obtained with a classical lamellar phase. Here the vesicles could not be destroyed at high shear rates but a butterfly pattern was observed in light and neutron scattering.
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    URL: http://dx.doi.org/10.1007/BF01182419
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    On-line measurement of elasticity and viscosity in flowing polymeric liquids (1996)
    Springer
    Rheologica acta 35 (1996), S. 110-116 
    Details
    ISSN: 1435-1528
    Keywords: Slit die ; on-line rheometry ; first normal stress difference ; hole pressure ; Stressmeter ; viscosity ; molten polymers ; multigrade oil elasticity ; high shear rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A new slit-die rheometer (the “Stressmeter”) for on-line and sample measurement of the viscosity, η, and the first normal stress difference, N 1, in steady shear flow for molten polymers and other high-viscosity liquids is described. Two liquid-filled transverse slots, located in one die wall near the center station, give pressures P 2 and P 3 from whose difference the wall shear stress σ is calculated. In the other die wall at a location opposite the center of the P 2 slot is a flush-mounted transducer, giving a pressure P 1. N 1 is calculated from the hole pressure P * = P 1−P 2. A metering pump, used to measure the flow rate Q, is supplied with melt either from an extruder (online mode) or from a pressurized sample cylinder (sample mode). The wall shear rate γ is calculated from Q and σ; the Weissenberg-Rabinowitsch correction and a new small-viscous-heating-correction algorithm (affecting σ) are used. Viscous heating corrections are small; entrance and exit errors are negligible. The instrument is tested by comparing its results with those obtained from cone-plate and capillary rheometers. Measurement ranges extend to σ = 200 kPa, γ = 3000 s−1, and temperature = 250°C.
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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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    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 
    Details
    ISSN: 1435-1528
    Keywords: Key words Translational diffusion ; probes ; rotation ; viscosity ; local segmental dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The translational diffusion coefficients of rubrene and tetracene in amorphous polyisobutylene (PIB) were measured using the holographic fluorescence recovery after photobleaching technique. Over the temperature range from 400 to 235K (T g =205K), tracer diffusion coefficients from 10–7 to 10–14cm2/s were observed. These diffusion coefficients have essentially the same temperature dependence as the rotational correlation times for these two probes in PIB. Both of these observables have a slightly stronger temperature dependence than does the viscosity. These results contrast strongly with the results of similar experiments on polystyrene and polysulfone. These results are consistent with the hypothesis that local segmental dynamics are more spatially homogeneous in PIB than in polystyrene and polysulfone.
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    Polymer contribution to the thermal conductivity and viscosity in a dilute solution (Fraenkel Dumbbell model) (1997)
    Springer
    Rheologica acta 36 (1997), S. 269-276 
    Details
    ISSN: 1435-1528
    Keywords: Key words Transport phenomena ; thermal conduction ; bead-spring models ; polymer solutions ; viscosity ; normal stresses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The phase-space kinetic theory for polymeric liquid mixtures is used to obtain an expression for the polymer contribution to the thermal conductivity of a nonflowing, dilute solution of polymers, where the polymer molecules are modeled as Fraenkel dumbbells. This theory takes into account three mechanisms for the energy transport: diffusion of kinetic energy (including the Öttinger-Petrillo term), diffusion of intramolecular energy, and the work done against the intramolecular forces. This paper is an extension of previous developments for the Hookean dumbbell model and the finitely-extensible dumbbell model. A comparison among the dumbbell results suggests that the thermal conductivity increases with chain stiffness. In addition, the zero-shear-rate viscosity and first normal-stress coefficient are also given for the Fraenkel dumbbell model.
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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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    Steady shear viscosity of short fibre suspensions in thermoplastics (1998)
    Springer
    Rheologica acta 37 (1998), S. 289-298 
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    ISSN: 1435-1528
    Keywords: Key words Reinforced ; thermoplastics ; viscosity ; convergent channel ; shear-thinning ; fibre suspension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The rheological behaviour of a polyethylene, two polyamides and a silicone oil filled with different fibre contents are studied in capillary rheometry. The viscosity increase induced by the fibres is important for the silicone oil, and negligible for the polyethylene. The polyamide is intermediate. The same classification stands for the pressure loss in the convergent channel upstream from the capillary. A constitutive equation based on a cell model which takes into account the shear-thinning behaviour of the matrix is built. The predictions of the model are in correct agreement with the measurements.
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    URL: http://dx.doi.org/10.1007/s003970050116
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    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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    Rheology and processing of salad dressing emulsions (1995)
    Springer
    Rheologica acta 34 (1995), S. 513-524 
    Details
    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 
    Details
    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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    Interparticle interaction in aerosol-OT microemulsion system studied by dynamic light scattering and viscosity (1997)
    Springer
    Colloid & polymer science 106 (1997), S. 79-82 
    Details
    ISSN: 1435-1536
    Keywords: w/o microemulsion ; AOT ; interparticle interaction ; dynamic light scattering ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Aerosol-OT water-in-oil microemulsions in isooctane was studied. By using dynamic light scattering and viscosity we measured two coefficients relating to hydrodynamic interparticle interaction, that is, α from DLS and Huggins coefficientk H from viscometry. TheW 0(=[H2O]/[AOT]) dependence of these coefficients in the range ofW 0=5–15 showed a critically different tendency compared to that in the rest of the range ofW 0 measured (W 0=15–50). The present results are in good agreement with our previous evidences which show the existence of an oligomeric phase in theW 0 range 5–15 using small-angle X-ray scattering.
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    Status of the round robin on the transport properties of R134a (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 63-78 
    Details
    ISSN: 1572-9567
    Keywords: R134a ; dilute gas ; refrigerant ; saturation properties ; 1,1,1,2-tetrafluoroethane ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper contains a status report on an international project coordinated by the Subcommittee on Transport Properties of Commission 1.2 of the International Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of R134a. The project has involved the remeasurement of the transport properties of a single sample of R134a in nine laboratories throughout the world in order to test the hypothesis that at least part of the discrepancy could be attributed to the purity of the sample. This paper provides an intercomparison of the new experimental results obtained to data in this project for the viscosity and the thermal conductivity in both gaseous and liquid phases. The agreement between the viscosity data from the laboratories contributing to the project was improved with several techniques, now producing consistent results. This suggests that the purity of the samples of R134a used in previous work was at least partly reponsible for the discrepancies observed. For the thermal conductivity in the liquid phase the results of the measurements are also more consistent than before, although not for all experimental techniques. Not all of the previous measurements suffered from significant sample impurities, so the present measurements on a consistent high-purity sample can he used to detect data sets which are outhers, possibly because of impurities. Identification of laboratories and techniques with systematic differences may require the examination of data for several fluids. The implications for future measurements of the transport properties of other refrigerants are significant.
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    Measurements of the viscosity of new refrigerants in the temperature range 270–340 K at pressures up to 20 MPa (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 133-143 
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    ISSN: 1572-9567
    Keywords: high pressure ; refrigerants ; vibrating wire ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A recently modified vibrating-wire instrument was employed to measure the liquid viscosity of a wide selection of new refrigerants under pressure. Calibration of the viscometer with water over the range of measurements confirmed that the estimated uncertainty of the measurements is 0.5%, while the precision is 0.3%. With this instrument, the viscosity of chlorofuorocarbons (CFC's) and alternative refrigerants. R11. R12. R22, R32. R124, R125. 11134a. R 141 b, and R152a, was measured over the temperature range from 270 to 340 K, from just above the saturation pressure up to 211 M Pa. The experimental data, represented by polynomial functions of temperature and pressure, are used in a comparative examination of other recently reported experimental measurements of the viscosity of all these refrigerants. to investigate the uncertainty with which the viscosity is known.
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    Critical dynamics of a sheared micellar solution (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 355-361 
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    ISSN: 1572-9567
    Keywords: critical dynamics ; micellar solution ; shear effects ; spinodal decomposition ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated the dynamic behavior of a nonionic micellar solution of tetra-ethylene glycoln-decylether (C10 E4) in water near its critical point in the presence of shear. The non-Newtonian behavior of the viscosityν can be represented byν ν* = [ 1 +a(Sτ4)=]ω2, whereν* is the viscosity in the absence of shear,S is the shear rate. τ4 is the lifetime of the critical Iluctuations,a is a system-dependent constant, and ω = 0.02 In addition, we have found that, before attaining a steady state, the sheared mixture undergoing phase separation shows significant shear-dependent rheological effects due to the presence of concentration domains.
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    The Viscosity of Toluene in the Temperature Range from 210 to 370 K at Pressures up to 30 MPa (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1367-1377 
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    ISSN: 1572-9567
    Keywords: toluene ; vibrating-wire technique ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper presents new measurements of the viscosity of toluene over a temperature range from 210 to 370 K, from the saturation line up to pressures of 30 MPa. The measurements were performed with a vibrating-wire viscometer. The uncertainty of the measurements, confirmed above room temperature with the measurement of the viscosity of water, is estimated to be ±0.5%.
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    URL: http://dx.doi.org/10.1023/A:1021428819290
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    Validation of an accurate vibrating-wire densimeter: Density and viscosity of liquids over wide ranges of temperature and pressure (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 781-802 
    Details
    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
    Topics: Physics
    Notes: Abstract A new vibrating-wire instrument for the meaasurement of the density of fluids at high pressures was described in a previous paper. The technique makes use of the buoyancy force on a solid sinker and detect, this force with a vibrating wire placed inside the measuring cell. Owing to the simple geometry of the oscillating element there exists a complete theoretical description of its resonance characteristics. enabling the calculation of the density of the fluid from their measurement. In the present paper a new method for the determination of the cell constants is outlined which permits the operation of the densimeter essentially as an absolute instrument. Furthermore. it is shown that the viscosity ol the fluid can be measured Simultaneously with the density. New results for three fluids are presented: for cyclohexane at temperatures from 298 to 348 K and pressures up to 40 MPa. for 2,2,4-trimethylpentane between 197 and 348 K at 0.1 MPa, and for 1,1,1,2-tetrafluoroethane from 197 to 298 K close to saturation. The sets of measurements where chosen with the intention of testing the performance of the apparatus. complementing previous work at higher pressures. The densities and viscosities measured exhibit the same accuracy for all of the three fluids over the entire temperature and pressure ranges and were obtained using the same set of cell parameters The precision of the densities is ±0.03% and their estimated accuracy is ±0.05%. File viscosities have a precision of ±0.6%, and an estimated accuracy of ±2%.
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    Revised Viscosities of Saturated Liquid Halocarbon Refrigerants from 273 to 353 K (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 909-912 
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    ISSN: 1572-9567
    Keywords: halocarbons ; refrigerants ; saturated liquid ; vapor buoyancy effect ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper presents revised saturated liquid viscosities for 15 halocarbon refrigerants, that is, R11, R12, R22, R13B1, R152a, R113, R123, R123a, R143a, R114, R134a, R141b, R142b, R225ca, and R225cb, reported in our previous papers [1, 2], in which the vapor buoyancy correction for the sealed capillary viscometer was not applied. The maximum corrections amount to from 1.2% for R225cb to 17.4% for R143a. The erroneous data in our previous papers should be considered obsolete except for the low-vapor density refrigerants R11, R123, R123a, R113, R141b, R225ca, and R225cb, for which the maximum correction is 2.4%.
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    URL: http://dx.doi.org/10.1023/A:1006666308831
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    Prediction of Fluid Mixture Transport Properties by Molecular Dynamics (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 437-448 
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    ISSN: 1572-9567
    Keywords: alkanes ; carbon dioxide ; diffusion ; mixtures ; molecular dynamics ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Equilibrium molecular dynamics simulations of mixtures of n-decane with methane, ethane, and carbon dioxide and of the mixture carbon dioxide–ethane were performed using the anisotropic united atoms model for n-decane and one-and two-center Lennard–Jones models for the light components. The Green–Kubo relations were used to calculate the viscosity, thermal conductivity, and inter- and intradiffusion. Viscosities are predicted with a maximum deviation of 30% at low gas concentrations and less than 10% deviation at high gas concentrations. The viscosity and thermal conductivity are less sensitive to the cross interactions than the diffusion coefficients, which exhibit deviations between models and with experiments of up to 60%.
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    URL: http://dx.doi.org/10.1023/A:1022513411043
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    Nonequilibrium Molecular Dynamics Simulation of the Rheology of Linear and Branched Alkanes (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 449-459 
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    ISSN: 1572-9567
    Keywords: alkanes ; nonequilibrium molecular dynamics ; order tensor ; rheology ; shear thinning ; viscosity ; viscosity index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Liquid alkanes in the molecular weight range of C20–C40 are the main constituents of lubricant basestocks, and their rheological properties are therefore of great concern in industrial lubricant applications. Using massively parallel supercomputers and an efficient parallel algorithm, we have carried out systematic studies of the rheological properties of a variety of model liquid alkanes ranging from linear to singly branched and multiply branched alkanes. We aim to elucidate the relationship between the molecular architecture and the viscous behavior. Nonequilibrium molecular dynamics simulations have been carried out for n-decane (C10H22), n-hexadecane (C16H34), n-tetracosane (C24H50), 10-n-hexylnonadecane (C25H52), and squalane (2, 6, 10, 15, 19, 23-hexamethyltetracosane, C30H62). At a high strain rate, the viscosity shows a power-law shear thinning behavior over several orders of magnitude in strain rate, with exponents ranging from −0.33 to −0.59. This power-law shear thinning is shown to be closely related to the ordering of the molecules. The molecular architecture is shown to have a significant influence on the power-law exponent. At a low strain rate, the viscosity behavior changes to a Newtonian plateau, whose accurate determination has been elusive in previous studies. The molecular order in this regime is essentially that of the equilibrium system, a signature of the linear response. The Newtonian plateau is verified by independent equilibrium molecular dynamics simulations using the Green–Kubo method. The reliable determination of the Newtonian viscosity from non-equilibrium molecular simulation permits us to calculate the viscosity index for squalane. The viscosity index is a widely used property to characterize the lubricant's temperature performance, and our studies represent the first approach towards its determination by molecular simulation.
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    URL: http://dx.doi.org/10.1023/A:1022565427881
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    Thermophysical Properties of Aqueous Solutions Near the Equilibrium Freezing Temperature (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 749-759 
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    ISSN: 1572-9567
    Keywords: aqueous solutions ; capillary-rise method ; surface tension ; thermal conductivity ; transient hot-wire method ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the surface tension, viscosity, and thermal conductivity of LiBr and LiSCN aqueous binary solutions have been performed to determine the thermophysical properties near the equilibrium freezing temperature. A differential capillary-rise method for surface tension and the transient hot-wire method for thermal conductivity were employed. Furthermore, a rotational viscometer was utilized for the measurement of viscosity. Correlation equations for the data of the aqueous binary test solutions as a function of temperature and concentration are presented.
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    The Effect of Model Internal Flexibility Upon NEMD Simulations of Viscosity (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 45-55 
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    ISSN: 1572-9567
    Keywords: viscosity ; NEMD simulation ; flexible models ; rigid bond lengths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The influence of model flexibility upon simulated viscosity was investigated. Nonequilibrium molecular dynamics (NEMD) simulations of viscosity were performed on seven pure fluids using three models for each: one with rigid bonds and angles, one with flexible angles and rigid bonds, and one with flexible bonds and angles. Three nonpolar fluids (propane, n-butane, and isobutane), two moderately polar fluids (propyl chloride and acetone), and two strongly polar fluids (methanol and water) were studied. Internal flexibility had little effect upon the simulated viscosity of nonpolar fluids. While model flexibility did affect the simulated viscosity of the polar fluids, it did so principally by allowing a density-dependent change in the dipole moment of the fluid. By using a rigid model with the same geometry and dipole moment as the average flexible molecule at the same density, it was shown that the direct effect of flexibility is small even in polar fluids. It was concluded that internal model flexibility does not enhance the accuracy of viscosities obtained from NEMD simulations as long as the appropriate model geometry is used in the rigid model for the desired simulation density.
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    URL: http://dx.doi.org/10.1023/A:1006600719847
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    Densities, Viscosities, Sound Speeds, and Excess Properties of Binary Mixtures of Methyl Methacrylate with Alkoxyethanols and 1-Alcohols at 298.15 and 308.15 K (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 1153-1174 
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    ISSN: 1572-9567
    Keywords: density ; methyl methacrylate +alcohol binary liquid mixtures ; molecular interactions ; relative association ; solvation number ; sound speed ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The densities, viscosities, and sound speeds were measured for six binary mixtures of methyl methacrylate (MMA)+2-methoxyethanol (ME), +2-ethoxyethanol (EE), +2-butoxyethanol (BE), +1-butanol (1-BuOH), +1-pentanol (1-PeOH), and +1-heptanol (1-HtOH) at 298.15 and 308.15 K. The mixture viscosities were correlated by Grunberg–Nissan, McAllister, and Auslander equations. The sound speeds were predicted by using free length and collision factor theoretical formulations, and Junjie and Nomoto equations. The excess viscosities and excess isentropic compressibilities were also calculated. A qualitative analysis of both of these functions revealed that structure disruptions are more predominant in MMA+1-alcohol than in MMA+alkoxyethanols mixtures. The estimated relative associations are found to become less in MMA+alcohol mixtures than in pure alcohols. The solvation numbers derived from the isentropic compressibility of the mixtures, considering MMA as a solvent, showed that structure making interactions are also present in MMA + alkoxyethanols in addition to the structure disruptions.
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    URL: http://dx.doi.org/10.1023/A:1026402222130
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    Thermophysical properties of natural gases for on-line metering (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 195-204 
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    ISSN: 1572-9567
    Keywords: ethane ; gas metering ; methane ; natural gas ; prediction ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The evaluation of the background transport properties of natural gas multicomponent mixtures over a moderate temperature and pressure range around ambient is considered in the context of the development of certifiable sensors for the measurement of mass and energy fluxes. The best available, theoretically based procedures to predict the properties are compared with experimental information to test the internal consistency, accuracy, and range of validity of the prediction. This is of primary concern to the demonstration of the viability of such sensors. It is shown that for low to moderate pressures, it is possible to achieve an internal consistency of the order of a few parts in a thousand and an accuracy of better than ± I %. At very high pressures the predictive scheme is also satisfactory, with errors of the order of a few percent. However, the procedure employed here systematically underestimates the thermal conductivity of the gas mixtures studied for intermediate pressures owing to the neglect of the critical enhancement even for temperatures quite far removed from the critical. The range of conditions for which the critical enhancement of the thermal conductivity is significant in mixtures is explored with data for binary mixtures of methane and ethane.
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    A new apparatus for measuring high viscosity of solids (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 577-584 
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    ISSN: 1572-9567
    Keywords: anelasticity ; laser interferometry ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new apparatus which is capable of measuring Newtonian viscosity as high as 108-1014 Pa · s has been developed. The upper and the lower faces of a cubic specimen 1 x 1 x I cm3 in size are respectively bonded to movable and fixed plates, and a constant shear stress is applied to the specimen. The displacement of the upper plate is measured and recorded as a function of time utilizing the HP-5528A optical laser measuring system. The sensitivity of the displacement measurement is 10 nm. Measurements at temperatures up to 200°C can be made by using a small furnace installed around the specimen. A variety of adhesive materials, polymers and ceramics, have been tested for the specimen-plate bonding. Aqueous Sauereisen cement showed a stable and rigid bonding in the experimental temperature range. Experiments for rubber (soft) and silicon crystal (hard) specimens have been performed to ascertain the reliability of the present method. The apparatus is also able to measure the anelasticity (mechanical relaxation) of solids, but is not adaptable to the measurement of the shear modulus of specimens; because the instantaneous displacement of the movable plate at the moment of the loading is mostly due to the rotational and inhomogeneous elastic deformations of the specimen.
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    URL: http://dx.doi.org/10.1007/BF01441923
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    Correlation and prediction of dense fluid transport coefficients. VII. Refrigerants (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 761-772 
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    ISSN: 1572-9567
    Keywords: density ; high pressure ; refrigerants ; Tail equation ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A recently developed scheme, based on considerations of hard-sphere theory, is used for the simultaneous correlation of the coefficients of viscosity and thermal conductivity for the refrigerants R11, R12, R22, R32. R124, R125, R134a, R141b, and R152a in excellent agreement with experiment, over extended temperature and pressure ranges. Values for the roughness factors and correlations for the characteristic volume are presented. The overall average absolute deviations of the experimental viscosity and thermal conductivity measurements from those calculated by the correlation are 2.1 and 2.3%, respectively, over a temperature range from 200 to about 10 K below the critical temperature and a pressure range from saturation to about 40 MPa. Since the proposed scheme is based on recent and accurate density values, a Tail-type equation was also employed to correlate successfully the density of the refrigerants. The overall average absolute deviation of the experimental density measurements from those calculated by the correlation is ±0.08%.
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    Correlation and extrapolation scheme for the composition and temperature dependence of viscosity of binary gaseous mixtures: Carbon dioxide + ethane (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1245-1255 
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    ISSN: 1572-9567
    Keywords: binary gaseous mixture ; carbon dioxide ; ethane ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental viscosity data of ethane, carbon dioxide, and three mole fractions of the binary system carbon dioxide + ethane in the temperature range 293.15〈T⩽633.15 K and in the density range 0.01⩽ρ⩽0.05 mol·L−1 reported earlier were evaluated simultaneously to find out a useful correlation and extrapolation scheme for the viscosity of binary systems in the range of moderate densities. A procedure based on the ideas of the modified Enskog theory has been found to give the best results. Dependent on temperature, the collision diameters related to the equilibrium radial distribution function at contact are fitted to viscosity values of the pure substances and of at least one mixture. The results are compared with experimental data from the literature. A recommendation is given concerning the density range in which the first density contribution to the viscosity coefficient of the system carbon dioxide + ethane is sufficient to be included.
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    URL: http://dx.doi.org/10.1007/BF02081292
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    Determination of the viscosity of various hydrocarbons and mixtures of hydrocarbons versus temperature and pressure (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1309-1334 
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    ISSN: 1572-9567
    Keywords: density ; high pressure ; hydrocarbons ; mixtures ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamic viscosityη and densityρ of 10 pure substances and three binary systems were measured as a function of temperatureT (298.15, 313.15, 333.15, 353.15, and 363.15 K.) and pressureP (⩽100 MPa). The pure substances were toluene,p-xylene,m-xylene,o-xylene, methylcyclohexane, methylnaphthalene, decahydronaphthalene, phenyldodecane, heptamethylnonane, and tetramethylpentadecane (pristane). The three binaries were toluene + tetramethylpentadecane, toluene + methylnaphthalene, and toluene + heptamethylnonane, for molar fractionsx of toluene ranging between 0 and 1. The three binaries are highly “contrasted” systems, i.e., systems in which the viscosities of the pure components are very different for eachP, T pair. In all, 547 experimental determinations were carried out (279 experimental data for viscosity of the pure substances and 268 data concerning the mixtures: x⊋0 and 1).
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    The viscosity of gaseous propane and its initial density dependence (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1335-1351 
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    ISSN: 1572-9567
    Keywords: n-alkanes ; propane ; second viscosity virial coefficient ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Results of five series of high-precision viscosity measurements on gaseous propane, each differing in density, are reported. The measurements were performed in a quartz oscillating-disk viscometer with small gaps from room temperature up to about 625 K and for densities between 0.01 and 0.05 mol · L−1. The experimental data were evaluated with a first-order expansion, in terms of density, for the viscosity. Reduced values of the second viscosity virial coefficients deduced from the zero-density and initial-density viscosity coefficients for propane and for furthern-alkanes are in close agreement with the theoretical representation of the Rainwater-Friend theory for the potential parameter ratios by Bich and Vogel. A new representation of the viscosity of propane in the limit of zero density is provided using the new experimental data and some data sets from literature. The universal correlation based on the extended principle of corresponding states extends over the temperature range 293 to 625 K with an uncertainty of ±0.5 % and deviates from earlier representations by about 1 % at the upper temperature limit.
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    Viscosities of HFC-32 and HFC-32/lubricant mixtures (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 75-83 
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    ISSN: 1572-9567
    Keywords: capillary viscometer ; free-volume model ; lubricant oil ; mixture ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A modified capillary tube method has been used to measure viscosities for HFC32 over a temperature range from -20 to 90°C and a pressure range from 0.1 to 5.3 M Pa, and for the liquid mixtures of HFC-32 with a synthetic polyolester oil at temperatures from 20 to 75°C and oil mass fractions from 0.44 to 1. Estimated uncertainties in the measured viscosities do not exceed ± 1.2 and ± 1.8°% for the pure fluocarbon and the mixtures, respectively. It is found that viscosity isotherms for HFC-32 at subcritical temperatures exhibit a minimum with increasing pressure, with the viscosity decreasing as much as 10% relative to its value at one atmosphere. Correlations are presented for dilute gas viscosities, excess viscosities, and saturated liquid and vapor viscosities. These correlations are shown to lit our data within experimental uncertainties. For HFC-32/lubricant mixtures, a free-volume viscosity model has been applied to correlate the experimental data.
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    The thermal conductivity and viscosity of acetic acid-water mixtures (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 111-125 
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    ISSN: 1572-9567
    Keywords: acetic arid ; aqueous mixtures ; thermal conductivity transient hot-wire technique ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity and thermal conductivity of acetic acid water mixtures were measured over the entire composition range and at temperatures ranging from 293 to 453 K. Viscosity measurements were performed with a high-pressure viscometer and thermal conductivity was measured using a modified transient hot-wire technique. A mercury filled. glass capillary was used as the insulated hot wire in the measurements. The l iscosity data showed unusual trends with respect to composition. At it given temperature. the viscosity was seen to increase with increasing acid concentration, attain a maximum. and then decrease. The thermal conductivity, on the other hand, decreased monotonically with acid concentration. A generalized corresponding-states principle using water and acetic acid as the reference fluids was used to predict both viscosity and thermal conductivity with considerable sucres.
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    Thermal conductivity and viscosity of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123) (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 293-328 
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    ISSN: 1572-9567
    Keywords: 2,2-dichloro-1,1,1-trifluoroethane ; HCFC-123 ; R123 ; thermal conductivity ; thermal diffusivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity and the viscosity data of CFC alternative refrigerant HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane: CHCI2-CF3) were critically evaluated and correlated on the basis of a comprehensive literature survey. Using the residual transport-property concept, we have developed the three-dimensional surfaces of the thermal conductivity-temperature-density and the viscosity-temperature-density. A dilute-gas function and an excess function of simple form were established for each property. The critical enhancement contribution was taken no account because reliable crossover equations of state and the thermal conductivity data are still missing in the critical region. The correlation for the thermal conductivity is valid at temperatures from 253 to 373 K, pressures up to 30 MPa, and densities up to 1633 kg m−3. The correlation for the viscosity is valid at temperatures from 253 to 423 K, pressures up to 20 MPa. and densities up to 1608 kg·m−3. The uncertainties of the present correlations are estimated to be 50% for both properties, since the experimental data are still scarce and somewhat contradictory in the vapor phase at present.
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    Saturated liquid viscosity correlations for alternative refrigerants (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 361-372 
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    ISSN: 1572-9567
    Keywords: ozone friendly ; refrigerants ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This article presents dimensionless equations for the temperature dependence of the saturated liquid viscosity of R32, R123 R124, R125, R134a. R141b. and R152a valid over a temperature range of engineering interest. The correlation has the form Φ n D =A +BT, where ΦD is the dimensionless fluidity (l ηD) andT D is a dimensionless temperature.n. A. andB are evaluated for each of the above refrigerants based on a least-squares fit to experimental data. This equation is found to provide an improved fit over those existing in the literature up toT D=0.8.
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    Excess volumes and excess viscosities of binary mixtures of 1-bromo-2-methylpropane + an isomer of butanol at 298.15 and 313.15 K (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 347-359 
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    ISSN: 1572-9567
    Keywords: activation energy ; binare mixtures ; free energy ; I-bromo-methypropane ; butanols ; viscosity ; excess volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Excess volumesV E, excess viscositiesη E, and excess free energies of activation of flow G*E at 298.15 and 313.15 K are reported for binary mixtures of 1-bronw-2-methypropane and each of the alcoholic isomers of I-butanol. The results were obtained from density and viscosity measurements and show positive values forV 4 and negative for bothη E andG *E for all mixtures over the entire composition range.
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    Mutual Diffusion Coefficient and Dynamic Viscosity Near the Critical Consolute Point Probed by Dynamic Light Scattering (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 791-803 
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    ISSN: 1572-9567
    Keywords: binary mixture ; critical consolute point ; dynamic light scattering ; mutual diffusion coefficient ; nitroethane–isooctane ; triethylamine–water ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The possibility of applying dynamic light scattering to simultaneous determination of the mutual diffusion coefficient and the viscosity of binary liquid systems was studied near the critical consolute point. When seed particles are added to the system, the particle diffusion coefficient is measured, and the viscosity is obtained using the Stokes–Einstein relation. Since the amplitude of light scattered from concentration fluctuations is low in a mixture with a small difference between the refractive indices of the pure components, this approach allowed the determination of the viscosity of a critical mixture of nitroethane and isooctane, without a signal component from mutual diffusivity superimposed. In contrast, particle aggregation prevented the determination of the viscosity of a critical mixture of triethylamine and water. Despite this difficulty, and an unidentified contribution in the signals obtained, the mutual diffusion coefficient and the critical exponent v could be determined in this system without a noticeable influence from the addition of seed particles.
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    Tests of Predictive Viscosity Models for Pure Liquids (1999)
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    International journal of thermophysics 20 (1999), S. 815-823 
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    ISSN: 1572-9567
    Keywords: alkanes ; alkanols ; alkenes ; aromatics ; corresponding states ; cycloalkanes ; esters ; liquids ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is of considerable importance to be able to predict accurately the viscosity of liquids over a wide range of conditions. In the present work, the ability of the three-parameter generalized corresponding states principle (GCSP) for the prediction of the viscosity of pure liquids is demonstrated. The viscosity of six different classes of pure liquids, viz., alkanes (19 compounds; 207 data points), cycloalkanes (6 compounds; 74 data points), alkenes (9 compounds; 146 data points), aromatics (4 compounds; 123 data points), alkanols (8 compounds; 89 data points), and esters (4 compounds; 28 data points) have been predicted over a wide range of temperatures using the three-parameter (T c, P c, θ) GCSP. Five options for the third parameter (θ) were studied, viz., Pitzer's acentric factor ω, molar mass M, characteristic viscosity η*, critical compressibility factor Z c, and modified acentric factor Ω, in addition to groups ωZ c and ΩZ c being treated as composite third parameters. Pressure effects were neglected. Good agreement between experimental and predicted values of viscosity was obtained, especially with either ω or η* being used as the third parameter. Furthermore, the viscosities of alkanes predicted by the TRAPP method and an empirical, generalized one-parameter model for liquid hydrocarbons provide comparisons with the more accurate GCSP method. The GCSP provides a simple and yet a powerful technique for the correlation and prediction of viscosities of a variety of pure liquids over a wide range of temperatures.
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    Viscosity and Surface Tension Measurements in Microgravity (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1005-1015 
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    ISSN: 1572-9567
    Keywords: Co–Pd alloy ; electromagnetic levitation ; liquid metals ; microgravity ; Pd–Cu–Si alloy ; surface tension ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity and surface tension of liquid metals can be measured by observing the oscillations of a levitated drop. The frequency is related to the surface tension, while the viscosity determines the damping of the oscillations. If no external forces are present, as in microgravity, these relations are particularly simple and precise. During the recent Spacelab mission MSL-1, such experiments have been performed on Co–Pd and Pd–Cu–Si using the electromagnetic levitation facility TEMPUS. It was possible to obtain data over a wide temperature range, including the undercooled regime. While the temperature dependence of the surface tension remains linear over the complete range, the temperature dependence of the viscosity is much more pronounced and is discussed in terms of different models.
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    High-Temperature Containerless Viscosity Measurement by Gas-Film Levitation (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1071-1083 
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    ISSN: 1572-9567
    Keywords: gas-film levitation ; high temperature ; oxide melts ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The gas levitation process development program has, so far, been focused mainly on contact-free manipulation, on molding and shaping of liquids, on high-temperature contact-free treatment, and on shaping and solidification of interesting materials for scientific and technical purposes. Recently proposed by Parayre for viscosity measurements, this process eliminates the perturbing effects of the container, in particular, that of crystallization when studying supercooled liquids. The method consists of extracting viscosity values from the damped decay of perturbed liquid drops floating on a gas-film. An apparatus has been designed and developed for viscosity values higher than 1 Pa·s and at temperatures up to 2000°C. The method was applied to a silicate glass of industrial interest containing 70 wt% per cent of SiO2, with viscosities ranging from 102 to 106 Pa·s. Experimental results are compared with the Vogel–Fulcher–Tamann law for viscosity predictions. This paper demonstrates the industrial and scientific interest of this new method for viscosity determinations, which can be used for the working and softening points of any glass. These results may lead to a better understanding of network-forming or network-modifying behavior in oxide glasses.
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    URL: http://dx.doi.org/10.1023/A:1022698619162
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    Viscosity of Binary Mixtures of Alkyl Acetates with Hexane, Tetrachloromethane, and Trichloromethane (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1449-1465 
    Details
    ISSN: 1572-9567
    Keywords: alkyl acetate ; chloromethane ; Gibbs energy of activation ; hexane ; liquid mixtures ; molecular interactions ; tetrachloromethane ; trichloromethane ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity η for binary mixtures of methyl acetate (MA), ethyl acetate (EA), n-amyl acetate (nAA), isoamyl acetate (iAA), decyl acetate (DeA), and dodecyl acetate (DoA) with hexane and of MA, EA, nAA, and iAA with tetrachloromethane and trichloromethane has been measured at 303.15 K over the entire range of composition. The viscosity data have been correlated with the equations of Grunberg and Nissan; Hind, McLaughlin, and Ubbelohde; Tamura and Kurata; Katti and Chaudhri; McAllister; Heric and Brewer; and Auslaender. The viscosity deviations Δη and excess Gibbs energy of activation ΔG*E of viscous flow based on Eyring's theory have been calculated. The results have been analyzed in terms of disruption of dipolar association of alkyl acetate and molecular interaction between alkyl acetate and chloromethane.
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    URL: http://dx.doi.org/10.1023/A:1021441122016
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    Transport properties of 1,1-difluoroethane (R152a) (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 731-757 
    Details
    ISSN: 1572-9567
    Keywords: 1,1-difluoroethane ; correlation ; critical region ; HFC-152a ; R152a ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Based on reliable. carefully selected data sets. equations for the thermal conductivity and the viscosity of the refrigerant R 112a are presented. They are valid at temperatures from 240 to 440 K, pressures up to 20 MPa. and densities up to 1050 kg · m−3. including the critical region.
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    URL: http://dx.doi.org/10.1007/BF01439187
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    Survey of Experimental Data of Thermophysical Properties for Difluoromethane (HFC-32) (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1653-1666 
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    ISSN: 1572-9567
    Keywords: critical parameters ; dielectric constant ; difluoromethane ; dipole moment ; heat capacities ; HFC-32 ; pvT behavior ; refractive index ; saturation densities ; second virial coefficient ; speed of sound ; surface tension ; survey ; thermal conductivity ; vapor pressure ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A survey of experimental data for HFC-32 was prepared at the Institute of Thermomechanics in connection with planned experiments. In tabular form, surveys of thermodynamic, transport, and other property measurements, including pvT behavior, second virial coefficient, vapor pressure, saturation densities, critical parameters, heat capacities, speed of sound, thermal conductivity, viscosity, surface tension, refractive index, dielectric constant, and dipole moment, are presented. Tables include author)s) name(s), reference, year of publication, ranges of measurements, number of points, stated uncertainty, sample purity, and experimental method.
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    URL: http://dx.doi.org/10.1023/A:1022697610870
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    Correlation for Viscosity and Thermal Conductivity of Liquid Halogenated Ethane Refrigerants1 (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 367-375 
    Details
    ISSN: 1572-9567
    Keywords: correlation ; hard spheres ; liquid ; refrigerants ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity and thermal conductivity of liquid halogenated ethane refrigerants from about 200 K to near the critical temperature, at saturation and also at pressures up to 50 MPa, are shown to be satisfactorily correlated on the basis of a scheme developed by Dymond and Assael from consideration of hard-sphere theory.
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    URL: http://dx.doi.org/10.1023/A:1006627411689
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    New Correlation Functions for Viscosity Calculation of Gases Over Wide Temperature and Pressure Ranges (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 1011-1031 
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    ISSN: 1572-9567
    Keywords: dense fluids ; Rainwater–Friend theory ; second viscosity virial coefficient ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of 14 supercritical gases over a wide temperature–pressure range is calculated with a new correlation scheme. Highly accurate realistic interatomic potentials of the noble gases are used in the Chapman–Enskog calculation of the zero-density viscosity and in the Rainwater–Friend theory to determine the initial density dependence of the viscosity. At densities beyond the range of the theory, a variant of the residual viscosity is developed. It is shown that the temperature dependence of the residual viscosity function increases with the number of atoms in the molecule. By including this temperature dependence, the accuracy of the predicted results improves significantly. The accuracy of this method is within the experimental uncertainties.
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    URL: http://dx.doi.org/10.1023/A:1026437702566
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    Saturated Liquid Viscosity and Surface Tension of Alternative Refrigerants (2000)
    Springer
    International journal of thermophysics 21 (2000), S. 1225-1253 
    Details
    ISSN: 1572-9567
    Keywords: dynamic light scattering ; R23 ; R32 ; R123 ; R125 ; R134a ; R143a ; R152a ; refrigerants ; surface light scattering ; surface tension ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Light scattering by thermally excited capillary waves on liquid surfaces or interfaces can be used for the investigation of viscoelastic properties of fluids. In this work, we carried out the simultaneous determination of the surface tension and the liquid kinematic viscosity of some alternative refrigerants by surface light scattering (SLS) on a gas–liquid interface. The experiments are based on a heterodyne detection scheme and signal analysis by photon correlation spectroscopy (PCS). R23 (trifluoromethane), R32 (difluoromethane), R125 (pentafluoroethane), R143a (1,1,1-trifluoroethane), R134a (1,1,1,2-tetrafluoroethane), R152a (1,1-difluoroethane), and R123 (2,2-dichloro-1,1,1-trifluoroethane) were investigated under saturation conditions over a wide temperature range, from 233 K up to the critical point. It is estimated that the uncertainty of the present surface tension data for the whole temperature range is less than ±0.2 mN·m−1. For temperatures up to about 0.95T c, the kinematic viscosity of the liquid phase could be obtained with an absolute accuracy of better than 2%. For the highest temperatures studied in this work, measurements for the kinematic viscosity exhibit a maximum uncertainty of about ±4%. Viscosity and surface tension data are represented by a polynomial function of temperature and by a van der Waals-type surface tension equation, respectively. The results are discussed in detail with comparison to literature data.
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    URL: http://dx.doi.org/10.1023/A:1006689724974
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    Liquid Viscosity of Binary Mixtures of Methanol with Ethanol and 1-Propanol from 273.15 to 333.15 K (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 3-13 
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    ISSN: 1572-9567
    Keywords: ethanol ; methanol ; mixtures ; 1-propanol ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The liquid viscosities and densities of two binary mixtures of methanol with ethanol and 1-propanol were measured in the temperature range from 273.15 to 333.15 K with a capillary viscometer and a glass pycnometer, respectively. The uncertainties in the measured viscosities were estimated to be smaller than 1.3%. The experimental viscosity values could be fitted to the Mertsch and Wolf equation within 2%.
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    URL: http://dx.doi.org/10.1023/A:1021438800094
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    Viscosity and Excess Volume at High Pressures in Associative Binaries (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 161-189 
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    ISSN: 1572-9567
    Keywords: excess activation energy of flow ; excess volume ; high pressure ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamic viscosity η and the density ρ of three pure substances (water, 2-propanol, diacetone alcohol) and the three associated binaries were measured versus temperature T (303.15, 323.15, and 343.15 K) and pressure P. For the binary systems the mole fractions x of each component were, successively, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1. For viscosity the experimental results (P≤100 MPa) represent a total of 540 data points: 54 for the pure substances and 486 for the binary mixtures (x≠0 and x≠1). For density the experimental results (P≤70 MPa) represent 1260 values: 126 for the pure substances and 1134 for the binary mixtures (x≠0 and x≠1). The mixtures with water are highly associative and the curves for the variation of η with composition exhibit a maxima. The variations of the excess activation energy of viscous flow ΔG E are discussed. Moreover, the measurements of ρ are sufficiently accurate to determine the excess volumes V E versus pressure, temperature, and composition.
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    A High-Temperature Viscometer for Molten Materials (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 427-435 
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    ISSN: 1572-9567
    Keywords: high temperature ; molten salts ; oscillating-cup viscometer ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An oscillating-cup viscometer for the measurement of the viscosity of molten materials from room temperature to 1400 K was developed. The instrument is described in detail and the working equations are presented. The operational behavior was tested with water at room temperature. Preliminary measurements show that the new viscometer is capable of measuring the viscosity of water at room temperature to within 0.2%. As the primary objective of this work is the establishment of standard reference data for high-temperature viscosity measurements in molten salts, molten metals, and molten semiconductors, references of earlier viscosity measurements of molten KNO3 are given.
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    URL: http://dx.doi.org/10.1023/A:1022561326972
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    Viscosity of Gaseous HFC-134a (1,1,1,2-Tetrafluoroethane) Under High Pressures (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1285-1295 
    Details
    ISSN: 1572-9567
    Keywords: HFC-134a ; Lennard–Jones potential ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of gaseous HFC-134a (1,1,1,2-tetrafluoroethane) was measured with an oscillating disk viscometer of the Maxwell type from 298.15 to 398.15 K at pressures up to 5.5 MPa. Intermolecular potential parameters for the Lennard–Jones 12-6 model were determined from the viscosity data at 0.1 MPa. The viscosity equation developed by Krauss et al. was applied to correlate the present viscosity data. In addition, the correlations proposed by Stiel and Thodos and by Lee and Thodos were tested for fitting the experimental viscosity data.
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    URL: http://dx.doi.org/10.1023/A:1021919215793
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    Prediction of the Viscosity of Supercritical Fluid Mixtures (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1297-1313 
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    ISSN: 1572-9567
    Keywords: high pressure mixture ; supercritical fluids ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method for predicting the viscosity of supercritical, multicomponent fluid mixtures, at any density, from the zero-density viscosity of pure components is presented. The method is based upon the results for a rigid-sphere model, suitably interpreted to apply to real fluids, and on the finding that the excess viscosity of pure supercritical fluids can be adequately described by a density function independent of temperature. The density range of the method extends to twice the critical density of the pure component with the smallest critical density. The only exception is for the methane-rich mixtures where the mixture density should not exceed 12000 mol·m−3. The uncertainty ascribed to the predictions made by this method is of the order of ±5%.
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    URL: http://dx.doi.org/10.1023/A:1021971232631
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    Viscosity of Aqueous Solutions of CO2 at High Pressures (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1315-1323 
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    ISSN: 1572-9567
    Keywords: carbon dioxide ; Flory's theory ; viscosity ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental viscosity measurements of aqueous solutions of CO2 along three isotherms at 273, 276, and 278 K for pressures up to 30 MPa are reported. The measurements have been carried out in a falling capillary viscometer and have an estimated uncertainty of ±1.5%. The experimental values were compared with the correlation proposed by Kanti et al. derived from Flory's theory. The equation is in poor agreement with the experimental values, but the equations of Kanti et al. and of Grunberg and Nissan with one adjustable parameter yield good agreement with the experimental data.
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    URL: http://dx.doi.org/10.1023/A:1021923316701
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    Viscosity and Density at High Pressures in an Associative Ternary (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1325-1341 
    Details
    ISSN: 1572-9567
    Keywords: density ; excess activation energy of viscous flow ; high pressure ; ternary mixture ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamic viscosity η and the density ρ of the associative ternary mixture water+diacetone alcohol+2-propanol have been measured as a function of temperature T (303.15, 323.15, and 343.15 K) and pressure P (≤100 MPa). The experimental results correspond to 698 values of η and ρ. With reference to the 54 values previously published on pure substances and 486 values for three corresponding binaries, the system is globally described by 1188 experimental values for various values of P, T and composition. The results for η are discussed in terms of excess activation energy of viscous flow.
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    URL: http://dx.doi.org/10.1023/A:1021975300772
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    Liquid Densities, Kinematic Viscosities, and Heat Capacities of Some Ethylene Glycol Dimethyl Ethers at Temperatures from 283.15 to 423.15 K (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 1343-1358 
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    ISSN: 1572-9567
    Keywords: corresponding states ; density ; ethylene glycol dimethyl ether ; group-contribution method ; heat capacity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Liquid densities and heat capacities at 1 MPa, and kinematic viscosities at atmospheric pressure of monoethylene glycol dimethyl ether (MEGDME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TrEGDME), tetrathylene glycol dimethyl ether (TEGDME), pentaethylene glycol dimethyl ether (PeEGDME), and polyethylene glycol 250 dimethyl ether (PEGDME 250) were measured in the temperature range from 283.15 to 423.15 K. For each substance, experimental data were correlated with temperature using empirical polynomial equations. The experimental data were also used to evaluate the predictive capability of some estimation methods of liquid densities and heat capacities for the studied ethylene glycol dimethyl ethers. The densities estimated by the Yen–Woods equation agree with our experimental values with a root-mean-square relative deviation (RMSD) of 3.21% for all ethylene glycol dimethyl ethers. The best estimated results of liquid heat capacities were obtained from the Rowlinson equation based on the corresponding-states principle, with a RMSD of 1.12%. The group-contribution methods give the worst results, especially at high temperatures.
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    URL: http://dx.doi.org/10.1023/A:1021927417610
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    Correlation and Prediction of the Transport Properties of Refrigerants Using Two Modified Rough Hard-Sphere Models (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 149-161 
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    ISSN: 1572-9567
    Keywords: viscosity ; thermal conductivity ; rough-hard-sphere ; refrigerants ; refrigerant mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two methods are presented for the correlation and prediction of the viscosities and thermal conductivities of refrigerants R11, R12, R22, R32, R124, R125, R134a, R141b, and R152 and their mixtures. The first (termed RHS1) is a modified rough-hard-sphere method based on the smooth hard-sphere correlations of Assael et al. The method requires two or three parameters for characterizing each refrigerant but is able to correlate transport properties over wide ranges of pressure and temperature. The second method (RHS2) is also a modified rough-hard-sphere method, but based on an effective hard-sphere diameter for Lennard–Jones (LJ) fluids. The LJ parameters and the effective hard-sphere diameter required in this method are determined from a knowledge of the density–temperature behavior of the fluid at saturation. Comparisons with the rough-hard-sphere method of Assael and co-workers (RHS3) are shown. We also show that the RHS2 method can be used to correlate as well as predict the transport properties of refrigerants.
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    Correlation of dense fluid self-diffusion, shear viscosity, and thermal conductivity coefficients (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 155-165 
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    ISSN: 1572-9567
    Keywords: correlation methods ; dense liquids ; diffusion coefficient ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A general procedure has been developed for simultaneously fitting any two of the self-diffusion coefficient, the viscosity (as the fluidity), and the thermal conductivity (as its reciprocal) as Dymond reduced coefficients, (D*,η*,λ*), to a simple function of the volume and the temperature for dense fluids. For example,D*=ζ1+ζ2 V r/(1+ζ3,/V r), whereV r=V[1-ζ1(T−T r)-ζ2(T−T r)2].T r is any convenient temperature, here 273.15 K. AsV r is common to the two properties, only eight coefficients, ζj and ζk are required. Such reduced transport-coefficient curves are geometrically similar for members of groups of closely related compounds. The procedure has been extended to give “family” curves for such groups by fitting a pair of transport properties for three substances from the group in a single regression. Overall, fewer coefficients are required than for other schemes in the literature, and the fitting functions used are simpler. The curves so constructed can be used for the correlation of data obtained from different sources, as well as interpolation and, to a limited extent, extrapolation. A comparison is made for a number of compotmd groups between simultaneous fits of the pairs (D−η ), (D−λ), and (η−λ)
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    URL: http://dx.doi.org/10.1007/BF01438966
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    Viscosity and density of liquid mixtures ofn-alkanes with squalane (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 773-779 
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    ISSN: 1572-9567
    Keywords: capillary viscometer ; density ; n-butane ; n-hexane ; squalane ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Viscosity and density measurements are reported for binary liquid mixtures ofn-butane andn-hexane with squalane in the temperature range from 273 to 333 K. The viscosity measurements have been carried out by using a capillary viscometer calibrated with standard liquids. that is. JS5, JSIO, JS20, and water. The uncertainty in the viscosity data was estimated to be ± 1.7%. The density needed for the calculation of the viscosity has been measured by using a glass pycnometer within an accuracy of ±0.04%. In the prediction of the viscosity, the scheme of Assael et al. fails for mixtures of this type differing greatly in size.
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    Measurement of density, sound velocity, surface tension, and viscosity of freely suspended supercooled liquids (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 545-555 
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    ISSN: 1572-9567
    Keywords: density ; levitation technique ; supercooling ; surface tension ; sound velocity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Noncontact methods have been implemented in conjunction with levitation techniques to carry out the measurement of the macroscopic properties of liquids significantly cooled below their nominal melting point. Free suspension of the sample and remote methods allow the deep excursion into the metastable liquid state and the determination of its thermophysical properties. We used this approach to investigate common substances such as water,v-terphenyl. succinonitrile, as well as higher temperature melts such as molten indium, aluminum, and other metals. Although these techniques have thus far involved ultrasonic, eletromagnetic, and more recently electrostatic levitation, we restrict our attention to ultrasonic methods in this paper. The resulting magnitude of maximum thermal supercooling achieved has ranged between 10% and 15% of the absolute temperature of the melting point for the materials mentioned above. The methods for measuring the physical properties have been mostly novel approaches, and the typical accuracy achieved has not yet matched the standard equivalent techniques involving contained samples and invasive probing. They are currently being refined, however, as the levitation techniques become more widespread and as we gain a better understanding of the physics of levitated liquid samples.
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    URL: http://dx.doi.org/10.1007/BF01441920
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    Viscosities of Multicomponent Silicate Melts at High Temperatures (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 309-323 
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    ISSN: 1572-9567
    Keywords: experiment ; model ; silicate melts ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the present work; the viscosities in the quaternaries CaO–Fe n O–MgO–SiO2, Fe n O-MgO–MnO–SiO2, and CaO–MgO–MnO–SiO2 and the quinary CaO–Fe n O–MgO–MnO–SiO2 were studied. The experimental technique employed was the well-established rotating cylinder method, using a Brookfield digital viscometer mounted over a specially designed graphite furnace. Generally, iron crucibles were used along with iron spindles. Periodic calibrations of the experimental setup were made using the standard reference slag recommended by the European Union. The measurement's were carried out up to a maximum temperature of 1773 K in all cases. The reliability of the measurements were checked at different rotation speeds as well as during thermal cycling, and excellent reproducibility of the results was noted. The experimental viscosity values were incorporated into a viscosity model. Equations based on the model for calculating the viscosities of the quarternary systems CaO–Fe n O–MgO–SiO2, Fe n O–MgO–MnO–SiO2, and CaO–MgO–MnO–SiO2 and the quinary system CaO–Fe n O–MgO–MnO–SiO2 are provided.
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    URL: http://dx.doi.org/10.1023/A:1021419406512
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