Intrinsic nonlinearity from LAOStrain—experiments on various strain- and stress-controlled rheometers: a quantitative comparison

Merger, Dimitri; Wilhelm, Manfred

doi:10.1007/s00397-014-0781-3

Cited by 36 publications

(8 citation statements)

References 38 publications

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“…The sample of 1,4-cis-polyisoprene used was anionically synthesized in the Karlsruhe laboratory ( M w = 84,000 g/gmol [59]; PDI ≡ M w M n = 1.04 [59]; M e = 4,000 g/gmol [60]; T g = −61.7ºC measured using differential scanning ( ), of the complex viscosity, η* ω ( ), were measured in parallel-disk flow using small-amplitude oscillatory shear flow with R = 8.0mm and h = 0.5mm [62,63] at T = 52.8°C with ! γ 0 ω < 0.01 , and we present these results in Figure 18.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The value λ = 0.0158s compares with the value of λ ≡ 1 ω c = 0.011s deduced from the crossover frequency, ω c [where Table 1 and in Figs. 2 a) and b) of [59]. Hence, the PI-84k, in cone-plate flow, seems to obey the single relaxation time corotational Maxwell model, include the slope of 2 [and thus the scaling exponent implied by Eq.…”

Section: Theory Versus Measurementmentioning

confidence: 97%

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Large-amplitude oscillatory shear: comparing parallel-disk with cone-plate flow

et al. 2015

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Theory Versus Measurementmentioning

confidence: 97%

Large-amplitude oscillatory shear: comparing parallel-disk with cone-plate flow

et al. 2015

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“…The data points affected by noise or inaccurate analysis of TA's TRIOS software were either excluded from the manuscript or the nonlinear viscoelastic parameters were recalculated from the Lissajous-Bowditch plots. As the LAOS measurements were performed on a stress controlled rheometer, the data can be affected by inertia [50]. An oscillatory mapping of the geometry was performed to compensate for the influence of instrument inertia.…”

Section: B Shear Rheometrymentioning

confidence: 99%

“…However, when the torque generated by instrument inertia is large, the rheometer's compensation routines are not sufficient to completely eliminate the effect of instrument inertia. To insure high quality data, the relative ratio of inertia torque to sample torque, T inertia =T sample , was checked for each experimental data point and was found to be very low, T inertia =T sample < 5%, indicating that the influence of inertia on the sample data is very small [50]. Any experimental artifacts such as wall slip and edge fracture are identified by examining the intensity of even harmonics which are sensitive to asymmetric artifacts [51].…”

Section: B Shear Rheometrymentioning

confidence: 99%

A comparison of linear and branched wormlike micelles using large amplitude oscillatory shear and orthogonal superposition rheology

Khandavalli¹,

Hendricks²,

Clasen³

et al. 2016

Journal of Rheology

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In this study, we present a comparative investigation of linear and branched wormlike micelles using two nonlinear rheological tools: orthogonal superposition rheology and large amplitude oscillatory shear (LAOS) rheology. The surfactants were a series of mixtures of octyl trimethyl ammonium bromide (C 8 TAB) and sodium oleate (NaOA). A transition from linear to branched wormlike micelles was obtained by either varying the relative ratio of NaOA to C 8 TAB at a fixed total surfactant concentration or by fixing the ratio of NaOA to C 8 TAB and varying the total surfactant concentration. Orthogonal superposition rheology imposes a small amplitude oscillatory shear strain over an orthogonally imposed shear flow to probe the effect of shear on the storage and loss modulus of the fluid. For both the linear and branched wormlike micelle solutions, the plateau modulus, the relaxation times, and the dynamic viscosity were all found to be sensitive to the strength of the orthogonally imposed shear rate. However, the nonlinear effects were much more pronounced for the case of the branched wormlike micelle solutions. This is likely due to a breakdown of the branched wormlike micelles under flow which can be inferred from the decrease in the plateau modulus and the subsequent increase in the calculated mesh size of the entangled micelle network with increasing orthogonal shear-rate. In the LAOS measurements, both the linear and branched wormlike micelles exhibited a qualitatively similar trend in the viscoelastic nonlinearities as the strain amplitude of the imposed oscillatory flow was increased. However, the strength of viscoelastic nonlinearities, both within an oscillatory cycle and with increasing strain amplitude, of the branched wormlike micelles was found to be significantly larger than those observed for the linear wormlike micelles. Additionally, at large strain amplitudes, the Lissajous-Bowditch plots of the branched wormlike micelle solutions were found to exhibit a secondary loop resulting from a negative elastic modulus. This is indicative of a stress overshoot and likely the result of a cyclical breakdown and reformation of the underlying wormlike micelle entangled structure during an oscillatory cycle. V

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“…Therefore, the visualization of the response signal of each measuring point is important and should be investigated. One approach to study the nonlinear response is the frequency distribution of the applied Fourier transformation Merger and Wilhelm 2014). Another possible approach is to plot the applied strain versus the measured stress in a Lissajousplot.…”

Section: Introductionmentioning

confidence: 99%

Shear localisation in interfacial particle layers and its influence on Lissajous-plots

Birbaum¹,

Haavisto

Koponen

et al. 2016

Rheol Acta

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Interfacial rheological measurements often show in their nonlinear Lissajous-plots rhombus or saddle-like shapes indicating complex local deformation behaviour. A strong interacting silica particle and an almost not interacting clay particle were studied in respect to their interfacial rheological properties. Large amplitude oscillation shear measurements were performed with a bicone geometry and combined with optical measurements, from which particle tracks were calculated. A correlation was found between the appearance of shear localisation and Lissajous-plot shapes. Silica particles showed shear localisation at the bicone edge and rhombic plateaus in the Lissajous-plot, while the shear localisation for the clay particles was observed at the cup's wall as saddle-like shaped Lissajous-plots

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Intrinsic nonlinearity from LAOStrain—experiments on various strain- and stress-controlled rheometers: a quantitative comparison

Cited by 36 publications

References 38 publications

Large-amplitude oscillatory shear: comparing parallel-disk with cone-plate flow

Large-amplitude oscillatory shear: comparing parallel-disk with cone-plate flow

A comparison of linear and branched wormlike micelles using large amplitude oscillatory shear and orthogonal superposition rheology

Shear localisation in interfacial particle layers and its influence on Lissajous-plots

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