A new approach for calculating the true stress response from large amplitude oscillatory shear (LAOS) measurements using parallel plates

Fahimi, Z Zahra; Broedersz, Chase P.; Kempen, Ths Thomas van; Florea, Daniel; Peters, Gwm Gerrit; Wyss, Hans M.

doi:10.1007/s00397-013-0738-y

Cited by 17 publications

(5 citation statements)

References 23 publications

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“…It was reported that method‐2 was less sensitive to experimental noise than method‐1, and also directly compatible with FT‐rheology. [ 29 ] Following these, different transient shear experiments on a shear thinning fluid and an elastoviscoplastic gel were performed and the extent of stress correction needed as well as corresponding influencing factors were discussed. [ 27 ] Further, model independent correction factors correlating higher harmonics of torque in parallel plate to that of stress in CP geometry, applicable only in the medium amplitude oscillatory shear (MAOS) regime were reported.…”

Section: Background: Reconciling Parallel Plate Measurementsmentioning

confidence: 99%

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Selection of geometry for nonlinear rheology using large amplitude oscillatory shear: Poly (vinyl alcohol) based complex network systems

Ramya

Deshpande

2023

Vinyl Additive Technology

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Oscillatory rheology is a common technique to characterize the linear and nonlinear mechanical response of complex materials. The present work studies two crosslinked systems of poly(vinyl alcohol) (PVA): physically crosslinked PVA-Borax, and glutaraldehyde (GA) based chemically crosslinked PVA-hyaluronic acid (HA) gel. Both exhibit nonlinear viscoelasticity with characteristic intracycle mechanisms during large amplitude oscillatory shear (LAOS), owing to H-bonding (physical) and covalent (chemical) interactions respectively, unlike PVA solutions/vinyl polymer melts. Parallel plate (PP) geometry is commonly utilized for rheology of crosslinked systems due to flexible gaps, and ease to retain exact material shapes. Unlike the widely employed cone and plate (CP) geometry for LAOS analysis, the inherent deformation and flow fields are not uniform in PP, which manifests as qualitative difference in the response of the material within the two geometries. A quantitative dissimilarity in the response of PVA based crosslinked systems is demonstrated in this work. Three approaches for PP correction from literature are explored to obtain a geometry independent response of the systems. Therein, the true stresses are computed from the apparent stresses via torque balance, their harmonics, and harmonic ratios based single-point correction. The first two are shown to have limited application, owing to their implicit assumption of geometry independence in the linear regime. The third approach is found to be effective upto medium strain amplitudes. We outline these shortcomings, and present guidelines to analyze PP LAOS results for the two PVA systems. The analysis can be generalized for the broader class of complex network systems' nonlinear rheology.cone and plate geometry, crosslinked polymers, oscillatory rheology, parallel plate geometry, poly(vinyl alcohol) | INTRODUCTIONVinyl polymers are versatile materials, and are a subject of extensive research since decades, owing to their ease of synthesis, degradation resistant carbon-carbon backbone, and good thermoplasticity. [1][2][3] They find applications in several fields ranging from construction, packaging, electronics, environmental protection to medical devices. [2,3]

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Section: Background: Reconciling Parallel Plate Measurementsmentioning

confidence: 99%

“…Several theories are available for parallel plate correction and are found to have their distinct range of applicability. [21][22][23][25][26][27][28][29][30][31][32] They are widely employed for steady/transient shear, but less often for oscillatory shear of complex polymeric systems.…”

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confidence: 99%

Selection of geometry for nonlinear rheology using large amplitude oscillatory shear: Poly (vinyl alcohol) based complex network systems

Ramya

Deshpande

2023

Vinyl Additive Technology

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“…In fact, due to this nonhomogeneous strain, varying as a function of radius, additional corrections could be applied to recover more accurate measurements for large amplitude deformations. 48 For linear elastic materials at low strain (far below yielding), we expect the shear stress to be linearly related to the shear strain multiplied by the elastic shear modulus, G, or…”

Section: Understanding Shear Stress and Strain In Sandwich Cookie Flowmentioning

confidence: 99%

On Oreology, the fracture and flow of “milk's favorite cookie®”

et al. 2022

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The mechanical experience of consumption (i.e., feel, softness, and texture) of many foods is intrinsic to their enjoyable consumption, one example being the habit of twisting a sandwich cookie to reveal the cream. Scientifically, sandwich cookies present a paradigmatic model of parallel plate rheometry in which a fluid sample, the cream, is held between two parallel plates, the wafers. When the wafers are counter-rotated, the cream deforms, flows, and ultimately fractures, leading to separation of the cookie into two pieces. We introduce Oreology (/ɔriːˈɒlədʒi/), from the Nabisco Oreo for “cookie” and the Greek rheo logia for “flow study,” as the study of the flow and fracture of sandwich cookies. Using a laboratory rheometer, we measure failure mechanics of the eponymous Oreo's “creme” and probe the influence of rotation rate, amount of creme, and flavor on the stress–strain curve and postmortem creme distribution. The results typically show adhesive failure, in which nearly allw (95%) creme remains on one wafer after failure, and we ascribe this to the production process, as we confirm that the creme-heavy side is uniformly oriented within most of the boxes of Oreos. However, cookies in boxes stored under potentially adverse conditions (higher temperature and humidity) show cohesive failure resulting in the creme dividing between wafer halves after failure. Failure mechanics further classify the creme texture as “mushy.” Finally, we introduce and validate the design of an open-source, three-dimensionally printed Oreometer powered by rubber bands and coins for encouraging higher precision home studies to contribute new discoveries to this incipient field of study.

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“…Yield strain γy of both unaged ( ) and aged (△) Laponite from oscillatory strain amplitude sweeps at a constant frequency (ω = 10 rad s −1 , the raw data with parallel plate correction [42][43][44]). (B) Inferred aging of yield stress, σy ≈ G ′ γy, using the value γy ≈ 25% with G ′ (τage) data in Fig.…”

Section: Fig 8 (A)mentioning

confidence: 99%