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  • 1
    Electronic Resource
    Electronic Resource
    Maximum Density for Flow of Dispersions of Near Monodisperse Spherical Particles (1994)
    s.l. : American Chemical Society
    Langmuir 10 (1994), S. 1439-1441 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00017a020
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  • 2
    Electronic Resource
    Electronic Resource
    Thermoreversible Gelation of Solutions of Syndiotactic Poly(methyl methacrylate) in Toluene: a Two-Step Mechanism (1994)
    s.l. : American Chemical Society
    Macromolecules 27 (1994), S. 7669-7676 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00104a023
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  • 3
    Electronic Resource
    Electronic Resource
    Experimental and theoretical analysis of band formation in polymeric liquid crystals upon cessation of flow (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 4759-4767 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00044a043
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamic characterization of liquid crystalline polymers under flow-aligning shear conditions (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 7736-7743 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dynamic response of liquid crystalline polymers at high shear rates has been studied by measuring shear and normal stresses during transients following a step in the shear rate. Stepwise increase and decrease as well as flow reversals have been investigated. A solution of poly(benzylglutamate) (PBG) in m-cresol is used in the experiments. One purpose of the work is to perform a comparison with the theoretical predictions that apply to the case of spatially uniform situations. The latter are expected to prevail at high shear rates, when the tumbling character of the nematic phase is effectively suppressed. The results indicate profound differences with respect to previous experiments at lower shear rates. A somewhat surprising result is that the behavior at high shear rates appears to be dominated by the viscous, rather than the elastic stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466816
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  • 5
    Electronic Resource
    Electronic Resource
    Orthogonal superposition measurements using a rheometer equipped with a force rebalanced transducer (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 4090-4096 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design of a device for rheological orthogonal superposition measurements on fluids is discussed. Superposing a small amplitude oscillatory motion on a steady or transient shear flow provides a technique to probe flow-induced microstructural changes in situ by means of mechanical spectroscopy. Oscillations perpendicular to the main shear flow possess intrinsic advantages over the parallel case. It is shown that the closed loop system of a force rebalanced transducer of an existing rheometer can be modified to drive an orthogonal oscillatory motion and to measure the material response. Nonhomogeneous flow, annular pumping or cavitation can occur and have to be avoided by means of a suitable flow cell. A double walled Couette cell, open at the bottom is suggested for that purpose. The device is evaluated with Newtonian fluids and with a viscoelastic polymer solution. The apparatus has two major advantages. First the forces associated with the main shear flow can be measured simultaneously with the orthogonal moduli. Second, the present design is implemented on an instrument already capable of performing parallel superposition measurements, hence the two superposition modes are available on a single instrument. The relative simplicity of the proposed modification could boost the use of orthogonal superposition measurements and facilitate the development of new applications, e.g., to probe the time evolution of the flow-induced anisotropy in complex systems. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148351
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  • 6
    Electronic Resource
    Electronic Resource
    Structure and dynamics of a polymer solution subject to flow-induced phase separation (1991)
    Springer
    Rheologica acta 30 (1991), S. 89-97 
    Details
    ISSN: 1435-1528
    Keywords: Mechanical rheometry ; polarimetry ; polystyrene ; segmental orientation ; flow-induced phase separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Experiments combining mechanical rheometry with polarimetry (birefringence and scattering dichroism) have been conducted on a 6% solution of polystyrene (1.86x106 molecular weight) in dioctyl phthalate. Birefringence is used to measure the extent of segmental orientation, whereas the dichroism is sensitive to orientation and deformation of concentration fluctuations associated with the process of flow-induced phase separation. The results indicate that these fluctuations grow predominately along the neutral (or vorticity axis) of a simple shear flow. At higher rates of shear, orientation in the flow direction is favored. The transition in orientation direction is accompanied by time-dependent behavior in the optical properties of the solution during shear and the onset of shear thickening of the viscosity and the first normal stress difference coefficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366798
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  • 7
    Electronic Resource
    Electronic Resource
    Rheological characterization of bimodal colloidal dispersions (1994)
    Springer
    Rheologica acta 33 (1994), S. 165-174 
    Details
    ISSN: 1435-1528
    Keywords: Colloidal suspensions ; bimodal dispersion ; viscosity ; dynamic moduli ; steric stabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract In order to investigate the effect of the particle size distribution on the rheological properties of concentrated colloidal dispersions both steady-state shear and oscillatory measurements have been performed on well-characterized bimodal dispersions of sterically stabilized PMMA particles. Replacing a minor amount of large particles by small ones in a concentrated dispersion, keeping the total effective volume fraction constant, decreases the viscosity quite drastically. On the other hand, replacing a small amount of small particles by big ones hardly effects the viscosity at all. This behavior can be attributed to the deformability of the stabilizing polymer layer. A procedure is proposed to calculate the limiting viscosities in a bimodal colloidal dispersion starting from the characteristics of the monodisperse systems. A good agreement has been obtained between the calculated values and the experimental results. The linear viscoelastic properties of the concentrated dispersions have been investigated by means of oscillatory measurements. The plateau values of the storage modulus for the bimodal dispersions decrease with an increasing fraction of the coarse particles. By substituting the bimodal dispersion by an equivalent monodisperse system the storage modulus can be superimposed on the values for the monodisperse suspensions when plotted as a function of the mean interparticle distance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00437301
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  • 8
    Electronic Resource
    Electronic Resource
    Structural hysteresis (1975)
    [s.l.] : Nature Publishing Group
    Nature 253 (1975), S. 618-619 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In mechanics, thixotropy is another typical example. It describes materials whose resistance to flow is lowered when subjected to mechanical agitation. In such a system the shear stress, T, will normally not be in phase with a shear rate, y, that is varied periodically. Hence a i-y plot will show a ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/253618a0
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  • 9
    Electronic Resource
    Electronic Resource
    In vitro experiments with an injection technique for cup fixation in total hip arthroplasty (1987)
    Springer
    Archives of orthopaedic and trauma surgery 106 (1987), S. 173-178 
    Details
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new technique has been developed to position the cup rigidly into the acetabulum during total hip joint replacement. After positioning the flanged cup on the acetabulum by means of screws, a low-viscosity cement is injected through a hole in the rim of the cup. A comparison with the standard cementing technique was made on the basis of in vitro experiments. For this purpose a mold was constructed to produce castings simulating the human acetabulum. The distribution of the cement, the pressure developed in the acetabulum, and the penetration of the cement are compared for the two cementing techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00452205
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamisches Verhalten von thixotropen Systemen, II (1972)
    Springer
    Rheologica acta 11 (1972), S. 203-209 
    Details
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Summary The rheological behaviour of a thixotropic system has been investigated in terms of the instantaneous structure. The system consists of magnesium silicate fibres, dispersed in a Newtonian. alkyd resin. The application of low frequency oscillatory measurements in the analysis of such materials is discussed. As the characteristic time for thixotropic recovery proved to be several orders of magnitude larger than the average relaxation time, the viscoelastic response of the instantaneous structures can be measured under vibrations of a suitable frequency. Using this technique changes in the relaxation spectrum due to stationary shearing are measured. Equilibrium structures under stationary and oscillatory flow are compared and the similarity principle between both types of measurements is tested for thixotropic systems. The rate of change of thixotropic recovery under rest and under vibrations is considered.
    Notes: Zusammenfassung Das rheologische Verhalten eines thixotropen Systems wurde als Funktion der momentanen Struktur untersucht. Das System besteht aus Magnesiumsilikat-Fasern, in ein Newtonsches Alkydharz dispergiert. Die Anwendung niedrigfrequenter Schwingungsmessungen in der Analyse solcher Materialien wird diskutiert. Es wird gefunden, daß die charakteristische Zeit für den thixotropen Strukturaufbau um Größenordnungen über dem mittleren Wert der viskoelastischen Relaxationszeit liegt. Es ist daher möglich, das elastoviskose Verhalten der momentanen Strukturen mit Schwingungsmessungen zu erfassen. Mittels dieses Verfahrens wurden Änderungen in dem Relaxationsspektrum, hervorgerufen durch stationäre Strömung, gemessen. Gleichgewichtsstrukturen in stationärer und schwingender Strömung wurden bestimmt, und die Analogie zwischen beiden wurde in dem Falle thixotroper Systeme nachgeprüft. Die Geschwindigkeit des Strukturaufbaus in Ruhe und unter Schwingungen wird betrachtet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01993021
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