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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Rheological study of mica-filled polypropylene as influenced by a coupling agent (1988)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 9 (1988), S. 419-425 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The rheological behavior of mica-filled polypropylene (PP) composites was investigated within the domain of linear viscoelasticity. The effect of mica concentration and of a silane coupling agent on material functions such as the complex viscosity (η*), the storage modulus (G') and the loss modulus (G") was examined. The dimensions of mica flakes were measured before and after coating with silane. The affinity of PP for the treated and non-treated mica was characterized. It was found that, for low mica concentration (〈30% by weight) the composite exhibits the classical viscoelastic behavior of a homogeneous material. For higher mica concentration, the material shows a strong heterogeneity as evidenced by an important drift at low frequencies in a Cole-Cole representation. It was also found that the presence of a silane coupling agent moves this critical concentration value up to 40% by weight.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750090608
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  • 5
    Electronic Resource
    Electronic Resource
    PVC filled with vacuum pyrolysis scrap tires-derived carbon blacks: An investigation on rheological, mechanical, and electrical properties (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 2159-2167 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Pyrolysis of scrap tires produces oil and carbon black (CB). The purpose of this work is to compare pyrolytic CBs with commercial grades as fillers for poly(vinyl chloride) (PVC). Blending of PVC with CB was performed in the melt at 180°C. The compositions prepared were 1,5,10,20, and 30 wt % of CB. The dynamic rheological, mechanical, and electrical properties of the PVC-CB composites were investigated. The results obtained for the storage modulus and complex viscosity of the composites of PVC with the pyrolytic CBs were between those of a high-grade (Monarch 1100) and a low-grade (Sterling R) commercial CBs. Intermediate tensile modulus, elongation at break, and electrical conductivity were also obtained. The specific surface area of the CB was shown to influence the composite properties. Reduction of the volatile matter and ash contents of the pyrolytic CB led to better properties of the PVC composites. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070461212
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  • 6
    Electronic Resource
    Electronic Resource
    Exit pressure effects in capillary die data (1985)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 669-676 
    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 exit flow from a capillary is analyzed with the help of macroscopic mechanical energy and momentum balances. The analysis shows that primary normal stress differences cannot be determined from the exit pressures under the assumption that the flow is viscometric down to the exit. This assumption and the second one (made by Han [9]) that both slit and capillary exit pressures are the same would lead to unacceptable results. Published exit pressure data for polyethylene melts are shown to be unreliable because of large hole-pressure errors in the pressure measurements. Pressure profiles obtained with a thin tube technique for the flow of a poly(isobutylene) solution indicate that the flow does not remain fully developed near the exit. Moreover, it is shown that for this polymer solution the excess viscous dissipation at the exit contributes to approximately 90 percent of the exit pressure.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760251105
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Highly elastic-constant vicosity fluids (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 459-464 
    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 rheological properties of three types of fluids that exhibit large normal stresses are examined and compared. These fluids have a constant or nearly constant viscosity and can be used as model viscoelastic fluids, covering a range of viscosity from 0.1 to 124 Pa.s. One lubricant, Emkarox FC 31-45000, is shown to have the characteristics of a second-order fluid. Series difficulties encountered in measuring the rheological properties of the Separan - corn syrup solutions (Boger fluids) are reported. The Emkarox and solutions of polyacrylamide (Pusher 700) in mixtures of glycerine and water are proposed as better model fluids.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760230808
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  • 9
    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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  • 10
    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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