Characterization of polymer dispersions by Fourier transform rheology

Kallus, S.; Willenbacher, Norbert; Kirsch, Stefan F.; Distler, Dieter; Neidhöfer, Thorsten; Wilhelm, Manfred; Spiess, Hans Wolfgang

doi:10.1007/s003970100184

Cited by 73 publications

(28 citation statements)

References 4 publications

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“…Regarding solid viscoelastic suspensions subjected to LAOS regime, a number of experimental works have been carried out, mainly focused on colloidal particles [e.g. Kallus et al (2001); Cracium et al (2003); Osman and Atallah (2006)]. Non-colloidal suspensions with spherical particles have been studied by Aral and Kaylon (1997).…”

Section: Rheology Of Viscoelastic Suspensions Of Spheres Under Small mentioning

confidence: 99%

“…The bulk shear stress and the resulting viscoelastic moduli are computed for increasing values of the strain amplitude and for different volume fractions and forcing frequencies. The non-linear response of the suspension is evidenced by Fourier-transform analysis [Neidhöfer and Wilhelm (2001); Kallus et al (2001); Klein et al (2007); Hyun et al (2011)]. Finally, the influence of the suspending fluid viscoelasticity on the particle microstructure is discussed and the potentialities and limitations of the proposed numerical method are summarized.…”

Section: Rheology Of Viscoelastic Suspensions Of Spheres Under Small mentioning

confidence: 99%

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Rheology of viscoelastic suspensions of spheres under small and large amplitude oscillatory shear by numerical simulations

D’Avino¹,

Greco²,

Hulsen³

et al. 2013

Journal of Rheology

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The dynamic response of a viscoelastic suspension of spheres under small and large amplitude oscillatory shear is investigated by three-dimensional direct numerical simulations. A sliding triperiodic domain is implemented whereby the computational domain is regarded as the bulk of an infinite suspension. A fictitious domain method is used to manage the particle motion. After the stress field is computed, the bulk properties are recovered by an averaging procedure. The numerical method is validated by comparing the computed linear viscoelastic response of Newtonian and non-Newtonian suspensions with previous theories and simulations. The numerical predictions are in very good quantitative agreement with experimental data for the Newtonian case, whereas deviations are found with respect to some sets of experiments for semidilute and concentrated viscoelastic suspensions. To investigate on such discrepancies, the effect of aggregates in the bulk of the suspension is examined. The simulations show that the presence of structures significantly alters the loss modulus. Such an effect is more pronounced as the volume fraction increases. In this light, the above mentioned disagreement between simulations and data (and among experimental data themselves) can be rationalized, as its origin can be attributed to inhomogeneous particle configurations. For increasing strain amplitudes, both loss and storage moduli depart from the linear viscoelastic values. Although the deviations are qualitatively similar to the large amplitude response of the unfilled suspending matrix, our results for dilute and semidilute suspensions show that the decrease of the moduli is more and more pronounced as the volume fraction is higher. Furthermore, a higher concentration of solid particles reduces the value of strain amplitude such that the nonlinear behavior is observed. Simulations at higher frequencies also correctly capture the overshoot in the loss modulus for intermediate strain amplitudes. Finally, the effect of fluid elasticity on the particle motion is analyzed. The particles are found to move away from their starting positions and the average distance, computed at the beginning of each cycle with respect to the initial configuration, linearly increases with the number of cycles. The change in the microstructure is attributed to the long-range hydrodynamic interactions mediated by fluid viscoelasticit

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Section: Rheology Of Viscoelastic Suspensions Of Spheres Under Small mentioning

confidence: 99%

Section: Rheology Of Viscoelastic Suspensions Of Spheres Under Small mentioning

confidence: 99%

Rheology of viscoelastic suspensions of spheres under small and large amplitude oscillatory shear by numerical simulations

D’Avino¹,

Greco²,

Hulsen³

et al. 2013

Journal of Rheology

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“…Heymann et al [78] have investigated highly concentrated suspensions of PMMA particles in PDMS, which show a combination of type I and type IV response like a soft gel, and also exhibited a local maximum in the intensity of the third harmonic. Kallus et al [50] characterized rigid polymer dispersions by FTRheology, and also found a local maximum in the Fourier intensities as a function of strain amplitude.…”

Section: Block Copolymer Solutionsmentioning

confidence: 99%

“…For the full reconstruction of a Lissajous curve, we also calculated strain using three different 1 st harmonic phase example: polymer melts [37,61], polymer blends [103], polymer solutions [71,94,104], block copolymer solutions [6,48,105], block copolymer melts [106], suspensions [5,12,14,50,107], ER materials [90,108], MR (magnetorheological) fluids [109], biological materials [110], wormlike micelle solutions [68] and food products [99,111], just to mention some prominent examples. In …”

Section: Nonlinear Shear Stress Waveformsmentioning

confidence: 99%

“…FT-Rheology was used for various complex fluids, such as polymer melts [34][35][36][37][38][39][40][41][42], polymer solutions [43,44], polymer blends [45][46][47], block copolymers [6,48,49] and dispersed systems [5,32,45,50]. Leblanc et al [51][52][53][54][55][56][57][58][59][60] systematically investigated various industrial elastomers and rubber materials with FT-Rheology, including EPDM rubber(ethylene propylene diene M-class rubber) [51][52][53], poly (vinyl chloride) (PVC)/ green coconut fiber (GCF) composites [54], carbon black filled rubber compounds [52,[55][56][57][58], natural rubber [59], polybutadiene rubber (BR) and styrene-butadiene rubber (SBR) [53,56], and thermoplastic vulcanizates (TPVs).…”

Section: Historical Survey Of Laosmentioning

confidence: 99%

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A review of nonlinear oscillatory shear tests: Analysis and application of large amplitude oscillatory shear (LAOS)

Hyun

Wilhelm

Klein

et al. 2011

Progress in Polymer Science

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Dynamic oscillatory shear tests are common in rheology and have been used to investigate a wide range of soft matter and complex fluids including polymer melts and solutions, block copolymers, biological macromolecules, polyelectrolytes, surfactants, suspensions, emulsions and beyond. More specifically, Small Amplitude Oscillatory Shear (SAOS) tests have become the canonical method for probing the linear viscoelastic properties of these complex fluids because of the firm theoretical background [1][2][3][4] and the ease of implementing suitable test protocols. However, in most processing operations the deformations can be large and rapid: it is therefore the nonlinear material properties that control the system response. A full sample characterization thus requires well-defined nonlinear test protocols. Consequently there has been a recent renewal of interest in exploiting Large Amplitude Oscillatory Shear (LAOS) tests to investigate and quantify the nonlinear viscoelastic behavior of complex fluids. In terms of the experimental input, both LAOS and SAOS require the user to select appropriate ranges of strain amplitude (γ 0 ) and frequency (ω). However, there is a distinct difference in the analysis of experimental output, i.e. the material response. At sufficiently large strain amplitude, the material response will become nonlinear in LAOS tests and the familiar material functions used to quantify the linear behavior in SAOS tests are no longer sufficient. For example, the definitions of the linear viscoelastic moduli G΄(ω) and G˝(ω) are based inherently on the assumption that the stress response is purely sinusoidal (linear). However, a nonlinear stress response is not a perfect sinusoid and therefore the viscoelastic moduli are not uniquely defined; other methods are needed for quantifying the nonlinear material response under LAOS deformation. In the present review article, we first summarize the typical nonlinear responses observed with complex fluids under LAOS deformations. We then introduce and critically compare several methods that quantify the nonlinear oscillatory stress response. We illustrate the utility and sensitivity of these protocols by investigating the nonlinear response of various complex fluids over a wide range of frequency and amplitude of deformation, and show that LAOS characterization is a rigorous test for rheological models and 3 advanced quality control.

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