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  • 1
    Electronic Resource
    Electronic Resource
    Rheological studies of moderately concentrated polystyrene solutions. I. A new method for the extrapolation of the zero-shear viscosity (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1205-1216 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of the viscosity coefficient η of solutions of polystyrene (Mw = 6.0 × 105 and 1.77 × 106) in trans-decalin (TD, θ solvent) and toluene (TL, good solvent) as function of shear rate (11-104 s-1), concentration (4.24-11.21 wt %), and temperature (10-50°C) are reported. As a new theoretically grounded method for the determination of the zero-shear viscosity η0 it is proposed to plot η as a function of $\left({\eta \dot \gamma} \right)^3$. The intercepts of the straight lines obtained by this procedure give η0 in good agreement with directly measured values.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210719
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  • 2
    Electronic Resource
    Electronic Resource
    Rheological studies of moderately concentrated polystyrene solutions in the vicinity of the θ temperature. II. Shear-rate dependence for different thermodynamic conditions (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1217-1226 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity data of moderately concentrated polystyrene solutions in trans-decalin (TD) (θ solvent, θ temperature 21°C) and toluene (TL) (good solvent) reported in Part I are discussed in terms of Graessley's entanglement theory. Under good solvent conditions, Graessley's master curve provides an excellent fit up to high shear rates, whereas in the vicinity of the θ conditions the data have to be modified by a parameter ηfric introduced by Ito and Shishido. The characteristic time of mechanical response to flow of chains approximately given by the shift factor τ0 is found in good solvents to be on the order of the Rouse relaxation time. In poor solvents, close to demixing, τ0 tends to much higher values, indicating a reduced chain mobility. The influence of temperature on the viscosity decreases with increasing shear. The resulting apparent energy of activation of flow shows very small or even negative values at high shear rates. This behavior can be explained by the modified Graessley theory, however, in a quite natural way.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210720
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  • 3
    Electronic Resource
    Electronic Resource
    Interdependence of enthalpic and entropic contributions to the second osmotic virial coefficient (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 847-856 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The interdependence of the enthalpic contribution A2, H and the entropic contribution A2, s to the second osmotic virial coefficient for a given polymer-solvent system has been investigated from the experimental and the theoretical point of view. Experimentally, the following common facts were observed for various systems at temperatures and pressures below the critical values for the solvent. Both the isobaric and isothermal dependences can be approximated over relatively wide ranges of A2, H by linear relations with a slope deviating only slightly, but in a characteristic manner from a value of -1. When the temperature is increased at constant pressure one moves along an isobar towards higher A2, H; when the pressure is increased at constant temperature, one moves along an isotherm in the opposite direction, i.e., towards lower A2, H. Theoretically this behavior can be described in a qualitative manner, starting from a relation derived by Patterson and Delmas on the basis of the Prigogine corresponding-states theory. The reasons for the lack of quantitative agreement are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100506
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  • 4
    Electronic Resource
    Electronic Resource
    Measured and calculated solubility of polymers in mixed solvents: Monotony and cosolvencyDedicated to Professor G. V. Schulz in honor of his 70th birthday. (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1115-1132 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By a study of two ternary systems, 4-heptanon-1-chlorobutane-poly(methyl methacrylate) and 2-butanol-1-chlorobutane-poly(methyl methacrylate), differing only in one component of the mixed solvent, two types of demixing behavior are demonstrated: i.e., a monotone change with composition of the mixed solvent (monotony), of which the first system is a good example, and the synergistic behavior (cosolvency) exhibited by the second system. The situation can be seen most clearly from the binodal edges (precipitation thresholds as a function of solvent composition) which were constructed from various types of sections through the binodal surface of the systems.In order to compare experimental results with theoretical calculations, we first characterized the binary subsystems. The polymer solutions, representing conventional (endothermal) theta systems, were investigated by light scattering and cloud point measurements. For the cosolvent 2-butanol-1-chlorobutane the necessary thermodynamic information was accessible from vapor pressure measurements. Applying the Prigogine-Patterson theory to the polymer solutions and using the single-liquid approximation of Scott for the ternary systems yielded theoretical binodal edges in good agreement with experiment except for the branch belonging to mixed solvents rich in 2-butanol. This finding is explained by an abnormal amplification of preferential solvation effects due to the existence of an association equilibrium of the alcohol via hydrogen bonds.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130605
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