A sensitive dynamic viscometer for measuring the complex shear modulus in a steady shear flow using the method of orthogonal superposition

Zeegers, Jch Jos; Ende, Dirk van den; Blom, C.; Altena, E. G.; Beukema, G.J.; Mellema, J.

doi:10.1007/bf00712320

Cited by 27 publications

(14 citation statements)

References 9 publications

(10 reference statements)

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“…A new method for dispersions has been developed to superimpose oscillations orthogonally onto a steady shear flow. Thus one probes the structural changes by the determination of G 4 at a certain shear rate (42). This method was used to probe ordering domains flowing in disordered material and corroborates the microstructural picture proposed in [17").…”

Section: Electrostaticmentioning

confidence: 95%

Experimental rheology of model colloidal dispersions

Mellema

1997

Current Opinion in Colloid & Interface Science

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Experimental rheological aspects of colloidal dispersions are now being investigated with improved skills and with better defined model systems. New methods allow more detailed investigations. The relationship between the rheological macroproperties, microproperties and processes is the focus of the most recent investigations. Better insight has been gained concerning this relationship.type of flow field is usually shear, because a well defined extensional flow for dispersions is still not an option. Addresses

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Section: Electrostaticmentioning

confidence: 95%

Experimental rheology of model colloidal dispersions

Mellema

1997

Current Opinion in Colloid & Interface Science

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“…Yet, there is a significant body of work that suggests the orthogonal superposition is extremely difficult to interpret. The idea originated in the polymer rheology community [59,60], but there is a consensus in the literature since then that strongly indicates that unambiguous interpretation of such data requires a valid non-linear constitutive model [61][62][63][64]. However, it does appear that the orthogonal superposition is more readily interpreted than is parallel superposition [63,64].…”

Section: Examination Of Their Full Dynamic Curves Reported In the Supmentioning

confidence: 99%

Exploring the validity of time-concentration superposition in glassy colloids: Experiments and simulations

Peng

Wang

et al. 2018

Phys. Rev. E

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Superposition approaches have generally been proposed to create a dynamic rheological map to access colloidal glassy dynamics beyond experimental time windows. However, the validity of the superposition approaches in colloids near the glass transition is questionable owing to the well-known emergence of a β-relaxation process there. Here, we employ a time-concentration superposition (TCS) approach, analogous to time-temperature superposition (TTS) and TCS approaches in molecular systems, utilizing a combination of macroscopic rheological experiments and microscopic Brownian dynamics (BD) simulations, where concentration jumps are performed by a sudden growth of particle size (soft PS-PNIPAM particles in experiment and nearly hard spheres in simulation) at a fixed number of particles. We have examined whether a characteristic master curve can be obtained through horizontal and vertical shifting of the dynamic data, finding that TCS does not hold for either the experimental or simulation systems. We identify the origin of this breakdown as not only the emergence of a strong β-relaxation process but also its overlap with the α-relaxation in both the experimental soft-sphere and the simulated near hard-sphere colloids near to the glass transition concentration. Further understanding of the lack of validity of TCS results from analysis of both experimental and simulation data in the framework of the Baumgaertel-Schausberger-Winter (BSW) relaxation spectrum which provide a means to determine the concentration dependences of both the α-and the β-relaxations, which seem to follow TCS themselves.

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“…Double walled Couette cells as used by Zeegers et al 10 have also been considered. A disadvantage of a double Couette cell is that, apart from an unavoidable difference in shear rate across the gap, the average shear rates are normally different at the two sides of the oscillating cylinder.…”

Section: Double Wall Couette Cellmentioning

confidence: 99%

“…Limitations of the device of Mewis and Schoukens were the difficulty in aligning the flow cell and the fact that the suspension of the device was not robust enough to cover a very wide range of viscosities. Recently, Zeegers et al 10 reported a somewhat similar device designed specifically for low viscosity fluids. Zeichner and Macosko 11 described orthogonal superposition measurements on polymer melts, using an on-line rheometer.…”

Section: Introductionmentioning

confidence: 99%

Orthogonal superposition measurements using a rheometer equipped with a force rebalanced transducer

Vermant

Moldenaers

Mewis

et al. 1997

Review of Scientific Instruments

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Articles you may be interested inNew high-temperature rotational rheometer for silicate melts, magmatic suspensions, and emulsions Rev. Sci. Instrum. 69, 3398 (1998); 10.1063/1.1149106 Experimental studies of an entangled polystyrene solution in steady state mixed type flowsThe 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.

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A sensitive dynamic viscometer for measuring the complex shear modulus in a steady shear flow using the method of orthogonal superposition

Cited by 27 publications

References 9 publications

Experimental rheology of model colloidal dispersions

Experimental rheology of model colloidal dispersions

Exploring the validity of time-concentration superposition in glassy colloids: Experiments and simulations

Orthogonal superposition measurements using a rheometer equipped with a force rebalanced transducer

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