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1

Digitale Medien

Rheology of Lyocell Solutions from Different Cellulose Sources (2000)

Collier, B. J. ; Dever, M. ; Petrovan, S. ; [weitere]

Springer

Journal of polymers and the environment 8 (2000), S. 151-154

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ISSN: 1572-8900

Schlagwort(e): Lyocell ; cellulose ; rheology ; viscosity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Energietechnik , Maschinenbau

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1014881901010

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2

Digitale Medien

Effect of Starch Granule Size on Viscosity of Starch-Filled Poly(hydroxy ester ether) Composites (2000)

Zhou, Genwen ; Willett, J. L. ; Carriere, Craig J. ; [weitere]

Springer

Journal of polymers and the environment 8 (2000), S. 145-150

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ISSN: 1572-8900

Schlagwort(e): Starch ; particle size ; composite ; viscosity ; polyester

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Energietechnik , Maschinenbau

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1014829916940

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3

Digitale Medien

Phenomenological equations for multicomponent fluids (1972)

Aono, Osamu

Springer

Journal of statistical physics 5 (1972), S. 113-125

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ISSN: 1572-9613

Schlagwort(e): Nonequilibrium thermodynamics ; electrolyte solution ; high-temperature plasma ; state variable ; forces and fluxes ; nonlocal linear relation ; Onsager reciprocity ; hydrodynamic equation of motion for component ; Navier-Stokes equation ; diffusion ; viscosity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract Ahydrodynamic equation of motion for each component of a multicomponent fluid is derived on the basis of nonequilibrium thermodynamics. Special care has been directed to the choice of state variables. In some limiting cases, this equation leads to customary phenomenological equations, such as the equation for diffusion and the Navier-Stokes equation. The viscosity is a consequence of nonlocal coupling of forces and fluxes. The reciprocity between the linear coefficients is examined closely.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01008374

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4

Digitale Medien

Transport Coefficients of Hydrogen and Argon–Hydrogen Plasmas (2000)

Murphy, A. B.

Springer

Plasma chemistry and plasma processing 20 (2000), S. 279-297

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ISSN: 1572-8986

Schlagwort(e): Transport coefficients ; transport properties ; viscosity ; thermal conductivity ; electrical conductivity ; diffusion coefficient ; Chapman–Enskog method ; hydrogen ; argon ; plasma

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Maschinenbau , Technik allgemein

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1007099926249

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5

Digitale Medien

Fluorescence Study of the Relaxation Process in Excited Hetarylthiazole Cations (2000)

Volchkov, V. V. ; Druzhinin, S. I. ; Kossanyi, J. A. ; [weitere]

Springer

Journal of fluorescence 10 (2000), S. 161-161

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ISSN: 1573-4994

Schlagwort(e): Excited state ; quinolyl ; structural relaxation ; viscosity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009447226786

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6

Digitale Medien

Energy Deactivation of Electronic Excitation of 2-N-Piperidine-5-(2",2"-Dicyanvinyl)Thiophene Depending on the Solvent Viscosity (2000)

Bondarev, S. L. ; Knyukshto, V. N. ; Tikhomirov, S. A. ; [weitere]

Springer

Journal of applied spectroscopy 67 (2000), S. 935-938

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ISSN: 1573-8647

Schlagwort(e): fluorescence ; viscosity ; picosecond spectroscopy ; conformer

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1004144623480

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7

Digitale Medien

Viscosity properties of mineral paraffinic base oils as a key factor in their primary biodegradability (2000)

Haus, Frédérique ; Junter, Guy-Alain ; German, Jean

Springer

Biodegradation 11 (2000), S. 365-369

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ISSN: 1572-9729

Schlagwort(e): aromatic hydrocarbons ; biodegradation ; CEC L-33-A-93 test ; lubricants ; mineral base oils ; viscosity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract The primary biodegradability of two types of paraffinic base oils (solvent and catalytically dewaxed oils) and their blends was evaluated using the CEC L-33-A-93 test. The biodegradability values varied between 10% and 75%. Base oil mixtures displayed varying contents in aromatic and polar compounds and a wide range of kinematic viscosity (KV) values, from roughly 10 to 600 cSt (at 40°C), while their viscosity indices were almost constant (90-100). The biodegradability of oils was closely related to their content in polycyclic aromatic hydrocarbons and was also decreasing with kinematic viscosity. For the two types of base oils, a linear relationship could be set between the biodegradation percentages and the logarithms of KV values. These results show that, beside overall chemical features such as the contents in aromatic compounds, KV may be a prominent parameter for assessing the primary biodegradability of mineral base oils.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1011672016757

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8

Digitale Medien

Revised Viscosities of Saturated Liquid Halocarbon Refrigerants from 273 to 353 K (2000)

Kumagai, A. ; Yokoyama, C.

Springer

International journal of thermophysics 21 (2000), S. 909-912

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ISSN: 1572-9567

Schlagwort(e): halocarbons ; refrigerants ; saturated liquid ; vapor buoyancy effect ; viscosity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: 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%.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1006666308831

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9

Digitale Medien

The Effect of Model Internal Flexibility Upon NEMD Simulations of Viscosity (2000)

Fuller, N. G. ; Rowley, R. L.

Springer

International journal of thermophysics 21 (2000), S. 45-55

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ISSN: 1572-9567

Schlagwort(e): viscosity ; NEMD simulation ; flexible models ; rigid bond lengths

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1006600719847

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10

Digitale Medien

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)

Sastry, N. V. ; Patel, S. R.

Springer

International journal of thermophysics 21 (2000), S. 1153-1174

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ISSN: 1572-9567

Schlagwort(e): density ; methyl methacrylate +alcohol binary liquid mixtures ; molecular interactions ; relative association ; solvation number ; sound speed ; viscosity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1026402222130

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