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  • 1
    Electronic Resource
    Electronic Resource
    End effects for highly elastic-constant viscosity fluids (1986)
    Springer
    Rheologica acta 25 (1986), S. 95-101 
    Details
    ISSN: 1435-1528
    Keywords: End effect ; elastic-constant viscosity fluid ; Boger fluid ; primary normalstress difference ; shear-thinning properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract In the light of a new interpretation, we have studied the end effects for highly elastic-constant viscosity fluids commonly called Boger fluids. In terms of entrance effect only, the presence of primary normal-stress differences in absence of shear-thinning properties results in a decrease of the entrance correction below the Couette (Newtonian) value, whereas the total end correction can be substantially increased by an amount which is strongly dependent on the Weissenberg number or recoverable shear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01332128
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  • 2
    Electronic Resource
    Electronic Resource
    Thermorheological analysis of glass beads-filled polymer melts (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 821-828 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The complex viscosity of two thermoplastic polymer melts (high density polyethylene and polystyrene) filled with polydisperse glass beads (10-53 μm) has been studied in the domain of linear viscoelasticity as a function of frequency, temperature, and filler concentration. In the experimental windows examined, the complex viscosity can be well described by a new empirical model, which contains a Cross-type viscosity model for the frequency dependence, a Quemada-type model for the filler concentration dependence, and a compensation effect for the temperature dependence. This model allows the prediction of the complex viscosity of a glass bead-filled thermoplastic melt provided only four parameters are known, namely: the average maximum packing volume fraction characteristic of the filler geometry and size distribution, the flow activation energy of the thermoplastic, the shear-thinning parameter, and an adjustable parameter, also characteristic of the thermoplastic.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301404
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  • 3
    Electronic Resource
    Electronic Resource
    Rheological simulation of in-line bubble interactions (1997)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 265-267 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690430130
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  • 4
    Electronic Resource
    Electronic Resource
    Finite element analysis of viscous mixing with a helical ribbon-screw impeller (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 939-944 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A finite element analysis was carried out to study the mixing patterns of a viscous Newtonian fluid into a stirred tank. A helical ribbon screw impeller (HRS) was used as the mixing device. The numerical simulation involved the full three-dimensional resolution of the equations of change governing the flow in the tank. The circulation time and the torque were determined and compared with experimental data. A good agreement was found, showing the usefulness of the numerical approach for design purposes.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690380614
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of pH on the batch fermentation of pullulan from sucrose mediumPresented at the 7th International Biotechnology Symposium, New Delhi, India, February 19-25, 1984. (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 202-207 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two strains of the yeast-like fungus Aureobasidium pullulans 2552 and 140B have been used for the fermentative production of the polysaccharide pullulan from a sucrose synthetic medium. In the batch fermentation, either in Erlenmeyers or in the fermentor, the pH of the culture medium was decreased rapidly from its initial pH value of 5.5 to the self-stabilized final value of 2.5 within 24 h. Experiments on the effect of initial pH on the fermentation revealed that at very low initial pH values, such as at pH 2, the polysaccharide production was in-significant. However, the biomass concentration obtained was very high at this very low initial pH value. This interesting phenomenon was served as the basic principle for the development of the bistaged pH fermentation process for the production of pullulan. In this process the first stage of fermentation was conducted at the very acidic pH for the best production of biomass. When the biomass concentration reached its maximum value, the second stage of fermentation was initiated by adjusting the medium pH to a higher value for promoting the synthesis of the polysaccharide. Experiments conducted in Erlenmeyers and in the fermentor confirmed this concept. The bistaged pH process enhanced the polysaccharide concentration in the medium, influenced the rheological properties of the fermentation broth, and has a potential of operation under nonsterile and nonaseptic conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270216
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of lactic fermentation on the rheological properties of κ-carrageenan/locust bean gum mixed gels inoculated with S. thermophilus (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 1403-1408 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260341110
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of shear on the inactivation kinetics of the enzyme dextransucrase (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1061-1067 
    Details
    ISSN: 0006-3592
    Keywords: protein ; inactivation ; shear ; denaturation ; aggregation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An inactivation model previously developed to characterize the rate of enzyme activity loss in unstirred solutions was extended to take into account orthokinetic interactions resulting from convective mixing. A synergistic relationship between shear rate and temperature was observed; the rate of inactivation of the enzyme dextransucrase was unaffected by the action of shear below 25°C, but was increased by the shear rate at 30°C. Shear rate does not appear to influence the equilibrium between native and denatured dextransucrase either directly in solution or indirectly by augmenting the turnover of the gas-liquid interface. However, a second-order plot of the inverse of relative activity (AO/A) versus Gt (shear rate × time) of dextransucrase at a constant temperature was linear because of the influence of shear on the coagulation of the denatured enzyme. The addition of 0.01 g L-1 of polyethylene glycol (MW 20,000) blocked this coagulation reaction, thereby completely inhibiting the shear-induced inactivation of dextransucrase at 30°C. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420907
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  • 8
    Electronic Resource
    Electronic Resource
    Compensation effects in viscosity-temperature dependence of polymer melts (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 529-533 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermal dependence of the parameters of the Carreau A model of viscosity has been investigated for 13 polymeric resins. It was shown that the zero-shear viscosity and the time constant obey an Arrhenius-type law and that, for these parameters, compensation effects are exhibited. The shear-thinning index was found to be fairly independent of temperature. An important consequence of a compensation effect is that only one determination of a parameter at a given temperature gives the complete temperature-dependence of this parameter.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280807
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  • 9
    Electronic Resource
    Electronic Resource
    On correlations of primary normal stresses in polymer solutions (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 1265-1272 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Primary normal stress difference data of some 32 different polymer solutions have been examined and correlated to the shear stress by a simple power-law model. The normal stress at constant shear stress is shown to increase with the molecular weight of the polymer, but decreases with the polymer concentration. The method proposed by Abdel-Khalik, et al., for predicting the primary normal stress difference from viscosity data for these polymer solutions is inadequate. The FENE-P dumbbell model is used to obtain master curves combining normal stress and viscosity data as a function of a dimensionless shear rate. It is found that this presents several drawbacks. It predicts shear-thinning effects with a power-law slope of -2/3, which is found to be too restrictive. The model fails to predict shear-thinning effects for dimensionless shear rates λEγ lower than approximately 0.5. It also fails to predict satisfactorily the low shear rate value of the dimensionless combination of viscosity and first normal stress coefficient Ψ1/λE(η - ηs). An empirically modified correlation is proposed. The fit for a series of polyacrylamide (Dow Separan AP-30) solutions is very good. In the case of a series of monodisperse polystyrene solutions, the fit is not as good, as the data show a more pronounced effect of polymer concentration at high shear rates.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760291809
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  • 10
    Electronic Resource
    Electronic Resource
    Rheology of polystyrene/poly(vinyl methyl ether)blends near the phase transition (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1573-1578 
    Details
    ISSN: 0887-6266
    Keywords: blends, polystyrene/poly (vinyl methyl ether), rheology near phase transition in ; rheology of polystyrene/poly (vinyl methyl ether) blends near phase transition ; viscoelasticity of blends near critical point ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mixtures are expected to show anomalous behavior in their viscoelastic properties close to a critical point. In this study, the reheological behavior of blends of polystyrene and poly (vinyl methyl ether) below, close to, and above the phase separation temperature Ts was investigated. Rheological measurements were carried out at three different compositions in the melt. Below and far from Ts, a satisfactory superposition of the storage and loss moduli G' and G″ was observed at all temperatures and frequencies. Close to Ts deviations were observed for G' at low frequencies (the so-called terminal zone). Above Ts G″ values was still observed over the whole range of frequencies and temperatures. The deviations observed for G' near Ts can be interpreted as due to the presence of significant concentration fluctuations. Plots of log (G'/G″2) as a function of temperature were shown to be sensitive to this anomalous behavior.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090291301
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