Driven torsion pendulum for measuring the complex shear modulus in a steady shear flow

Ende, Dirk van den; Mellema, J.; Blom, C.

doi:10.1007/bf00373241

Cited by 11 publications

(4 citation statements)

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“…Linear viscoelastic measurements were also performed at high frequencies, using three torsion resonators and a nickel tube resonator. Those instruments were developed in our laboratory and details on design and principle can be found in Oosterbroek et al, Blom and Mellema, and van den Ende et al With those instruments, dynamic moduli of weak gels can be measured at a discrete set of frequencies between 70 Hz and 250 kHz, at ambient temperatures. To allow interpretation of the results the surface loading criterion should be satisfied .…”

Section: Methodsmentioning

confidence: 99%

“…Those instruments were developed in our laboratory and details on design and principle can be found in Oosterbroek et al, Blom and Mellema, and van den Ende et al With those instruments, dynamic moduli of weak gels can be measured at a discrete set of frequencies between 70 Hz and 250 kHz, at ambient temperatures. To allow interpretation of the results the surface loading criterion should be satisfied . This means that the shear wave generated by the torsion bar must be damped significantly before it is reflected by the walls of the container.…”

Section: Methodsmentioning

confidence: 99%

“…To allow interpretation of the results the surface loading criterion should be satisfied. 10 This means that the shear wave generated by the torsion bar must be damped significantly before it is reflected by the walls of the container. For the data presented in this paper, this criterion was satisfied.…”

Section: Mesoscopic Observationsmentioning

confidence: 99%

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Linear Rheology of Guar Gum Solutions

et al. 2000

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We have investigated the linear viscoelastic behavior of guar gum solutions as a function of frequency, temperature, polymer concentration, and molecular weight. This was done to sort out the importance of different relaxation mechanisms like reptation or the breakup of physical bonds. In the kilohertz regime, Rouse behavior is observed. At lower frequencies, two storage modulus plateau zones were found, indicating two additional relaxations. One is operative between 1 and 100 Hz and gives rise to a very broad relaxation spectrum, even for monodisperse guar. Describing the dependencies of the relaxation time and low-shear viscosity on concentration and molecular weight with power laws resulted in unusually high coefficients. The second relaxation becomes manifest below 0.01 Hz and has not been earlier reported. Here the temperature dependence is very strong whereas all other dependencies are weak. Analyzing the experiments with existing models for transient polymer networks revealed that at best a partial decription of the experimental dependencies can be obtained. It was concluded that at least two different relaxation mechanisms must play a role, classical reptation not being one of these. Best overall predictions were obtained with a model assuming two types of associations. However, also the picture of star polymer-like structures held together via bonds with a long lifetime could give comparable predictions. For a further distinction between these mechanisms, more information about the mesoscopic structure is needed.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Linear Rheology of Guar Gum Solutions

et al. 2000

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“…In order to study the linear viscoelastic properties of a complex fluid while it is in a steady shear state a new torsion pendulum apparatus was developed by Van den Ende et al (1992) a few years ago. With this apparatus a small amplitude shear deformation is superimposed parallel on a steady shear flow.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 1995

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A new instrument to carry out complex viscosity measurements in equilibrium and in a steady shear flow has been developed. A small amplitude harmonic excitation is superimposed orthogonally to the steady shear rate component. It is realized by a thin-walled cylinder, which oscillates in the axial direction in a rotating annular cup. The cylinder is suspended from a spring and guided by an air bearing. The spring, which itself is attached to an axially oscillating exciter, has been designed especially for a low linear and a large torsional spring constant. The motion of the cylinder and exciter is recorded and analysed. The applicable frequency ranges from 0.001 up to 50 Hz, the steady shear rate from 0.001 up to 100 s-1 and the oscillatory shear amplitude from 3 down to 0.003. The temperature can be set and controlled between 5 ° and 70°C.

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