Shear-banding fluid(s) under time-dependent shear flows. Part I: Spatiotemporal dynamics

Abstract

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Isolating the effects of thixotropy in geopolymer pastes

“…The small notch located in the low shear portion of the data could be reflective of the film breaking due to the rotation of the spindle and becoming more visible for trials that had an extended wait time. This small feature could also be evidence of shear banding, which occurs in many types of complex fluids 46 . The manner in which the lines correlated with one another could have been an indication of which specific portion of the polymerization reaction the paste had undergone before shearing.…”

“…This small feature could also be evidence of shear banding, which occurs in many types of complex fluids. 46 The manner in which the lines correlated with one another could have been an indication of which specific portion of the polymerization reaction the paste had undergone before shearing. There were three distinct groupings of the first ramp stress curves: A period of 0-30 min were relatively spaced equally from one another, 40-80 min that lay on a similar stress curve, and lastly, 90-140 min that also lay on a similar stress curve located above the rest of the curves.…”

Heterogeneity-induced retraction in viscoelastic fluids following cessation of flow

“…8,41 The increase in shear stress at the end of the stress plateau likely corresponds to the onset of elastic instabilities, as seen in other WLM solutions. 47,50–52…”

“…8,41 The increase in shear stress at the end of the stress plateau likely corresponds to the onset of elastic instabilities, as seen in other WLM solutions. 47,[50][51][52] The gel-like rheological properties of P234-NaCl were previously characterized in D 2 O, 14 but are characterized here due to differences in poloxamer batch and solvent. As a result, the viscoelastic aging rate is slightly faster in this formulation.…”