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  • 1
    Electronic Resource
    Electronic Resource
    Dependence of non-Newtonian flow properties of polystyrene solutions on solvent viscosity (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 399-407 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Steady shear viscosities were measured over a range of shear rates from lower to upper-Newtonian flow region for solutions of polystyrene in the high-viscosity solvent tricresyl phosphate at three different temperatures. The influence of solvent viscosity on the non-Newtonian flow property was studied and compared with the results obtained previously by use of a lowviscosity solvent with similar solvent power for polystyrene as tricresyl phosphate. For the moderately concentrated solutions, the non-Newtonian viscosity could be explained by Graessley's entanglement viscosity theory modified by a frictional viscosity. The result shows that only the frictional viscosity is affected by variation of solvent viscosity. As the entanglement viscosity decreases with increasing shear rate and is practically masked by the shear independent frictional viscosity, the flow appears as to be upper-Newtonian in spite of the difference in solvent viscosity. The lower critical concentration for entanglement was determined on the basis of a lower limit for the applicability of the modified Graessley theory. The values of the critical concentrations are independent of the magnitude of solvent viscosities.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1980.021810210
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  • 2
    Electronic Resource
    Electronic Resource
    Critical molecular weight for onset of non-newtonian flow and upper newtonian viscosity of polydimethylsiloxane (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 10 (1972), S. 2239-2248 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The flow curves of fractionated polydimethylsiloxanes of different molecular weights were obtained over a wide range of shear rates, from 3 × 10-1 to 4.3 × 106 sec-1, by use of a gas-driven capillary viscometer designed to decrease the experimental error in high shear rate region. Non-Newtonian flow can occur at molecular weights below the critical molecular weight Mc for the entanglement of polymer chain. The critical molecular weight M′c for the onset of the non-Newtonian flow is identical with that of the segment of viscous flow. For the polymer of molecular weights from M′c to Mc, the upper Newtonian viscosity increases with an increase in molecular weight. Above Mc, the upper Newtonian viscosity is almost independent of the molecular weight.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.180101111
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Non-Newtonian behavior in steady flow over the range from the lower to the upper Newtonian region for polystyrene solution (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 35-41 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Graessley's entanglement theory of viscosity modified by a frictional viscosity parameter ηfric is applied to data on solutions of polystyrene in diethyl phthalate at various concentrations and different temperatures. All the data modified give a single master curve over the entire rates of shear, as obtained previously with polydimethyl-siloxanes of various molecular weights and their solutions of various concentrations. The zero-shear viscosity η0, the upper Newtonian viscosity η∞, and ηfric are compared. Three activation energies for flow are estimated from η0, η∞ and ηfric, and are compared. The result suggests that the flow behavior in the upper Newtonian region is much more dependent on ηfric than on the entanglement viscosity term ηent. The ratio of zero-shear entanglement viscosity ηent,0 to ηfric can be used as a measure of the non-Newtonian behavior of the present solutions. Non-Newtonian behavior of the investigated polymer solution becomes appreciable at about ηent,0/ηfric = 2.5. These results are in agreement with previous conclusions based on comparison between η0, η∞ and ηfric for polydimethyl-siloxanes and their solutions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130104
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  • 4
    Electronic Resource
    Electronic Resource
    Non-Newtonian flow curves including lower and upper Newtonian regions for dilute and moderately concentrated polystyrene solutions (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 725-734 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The non-Newtonian viscosity in steady flow was measured for solutions of polystyrene (M̄w/M̄n = 1.1) in diethyl phthalate at 30.0°C. In the moderately concentrated solutions, from 6.03 × 10-2 to 5.62 × 10-1g/cm3, the viscosity data modified by frictional parameters fit the Graessley theoretical curve for a narrow distribution polymer. The dilute solutions, from 3.26 × 10-3 to 1.57 × 10-2 g/cm3, were nonentangled systems whose non-Newtonian properties could be explained by the excluded volume effect as proposed by Fixman. On the basis of the non-Newtonian data, it was concluded that the solution of 3.30 × 10-2 g/cm3 was a lower critical entanglement concentration, which was distinguished from the usual higher critical concentration for entanglement. This lower critical concentration was also found in the concentration dependence of the activation energy of flow and the absorbance at 310 nm.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.180160414
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  • 5
    Electronic Resource
    Electronic Resource
    Modified graessley theory for non-newtonian viscosities of polydimethylsiloxanes and their solutions (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 617-628 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A deviation from Graessley's theory of entanglement viscosity appears at very high shear rates when the flow of polydimethylsiloxanes of various molecular weights and their solutions with various concentrations is measured by the capillary method. In order to explain this deviation, a modified Graessley theory is proposed according to the previously reported suggestion that frictional viscosity appears not to be negligible at high shear rates. A reducing procedure taking a frictional viscosity parameter into account was performed. All of the reduced data are combined to give a master curve in spite of a wide range of molecular weight, concentration, and shear rate (from the lower Newtonian to very highest non-Newtonian flow region). The findings from the reducing procedure completely explain the mechanism of non-Newtonian flow for the bulk polymers with various molecular weights, including those below the critical molecular weight for entanglement, and for polymer solutions at any concentration. The viscosity of the linear polymer system consists of the shear-dependent entanglement term ηent proposed by Graessley and the shear-independent frictional term ηfric. The non-Newtonian behavior depends on the ratio of ηent/ηfric at the shear rate of measurement. The ratio of zero-shear entanglement viscosity ηent,0 to ηfric and the critical shear rate for onset of the non-Newtonian flow may be used as a measure of the non-Newtonian behavior of the system and a measure of capability for its rising, respectively. The Graessley theory is to be included in the present modified theory and is applicable to the case of ηentηfric ≫ 1.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120313
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  • 6
    Electronic Resource
    Electronic Resource
    Steady-shear viscosity of polydimethylsiloxanes over the range from the lower to the upper Newtonian region (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 2283-2289 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of non-Newtonian behavior for flow from the lower to the upper Newtonian region is explained by a modification of Graessley's theory. In the theory proposed here, a viscosity ηfric, which is based on friction between polymer segments and is almost shear-independent, is introduced in addition to Graessley's entanglement viscosity ηent, which decreases with increasing shear rate. The theory is applied to previously obtained data on steady flow of polydimethylsiloxanes of different molecular weights. The agreement between calculated and experimental results is good. In polymers with the molecular weight above the critical molecular weight for entanglement Mc, the major contribution to viscosity near zero shear rate is ηent. As the shear rate increases, the flow curve has an inflection where ηfric cannot be disregarded in comparison with ηent. In the upper Newtonian region, ηfric has more influence on the viscosity than ηent. The theory can also explain the experimental results on flow of polymers with molecular weight below Mc, which were shown to be slightly non-Newtonian in the previous paper.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.180111117
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  • 7
    Electronic Resource
    Electronic Resource
    Capillary end-correction in the upper newtonian region (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 10 (1972), S. 2097-2100 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.180101021
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