Dependence of suspension complex viscosity on frequency: Strain-controlled vs. stress-controlled tests

Martone, Raffaella; Paduano, Liana P.; Carotenuto, Claudia; Minale, Mario

doi:10.1063/1.5046047

Cited by 4 publications

(3 citation statements)

References 24 publications

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“…In the literature, it is generally assumed that if SS is rate-independent, OS is also frequency-independent. However, recent experiments challenge this assumption and demonstrate a frequency-dependent rheology in the absence of any ratedependence in SS [13][14][15]. In this Letter, we combine experiments with simulations and show that weak repulsive or adhesive interparticle forces are enough to induce the sought frequency-dependence in OS, while keeping SS rate-independent.…”

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confidence: 79%

Weakly adhesive suspension shows rate-dependence in oscillatory but not steady shear flows

Ge,

Martone,

Brandt

et al. 2020

Preprint

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confidence: 79%

Weakly adhesive suspension shows rate-dependence in oscillatory but not steady shear flows

Ge,

Martone,

Brandt

et al. 2020

Preprint

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“…In particular, the obtained equations should be extended to a relation between viscosity and shear rate. This can be straightforwardly done invoking the renowned Cox–Merz rule that is known to be valid for homogenous and heterogeneous fluids, though for the latters only in the limit of low concentrations . Moreover, the TTCS allows fully characterizing the viscoelasticity of a polymer by a single quick experiment: A cooling ramp at fixed frequency, followed by a frequency sweep test at constant temperature (Fig.…”

Section: Resultsmentioning

confidence: 99%

Non‐Isothermal Crystallization Kinetics of an Ethylene‐Vinyl‐Acetate. II. Time‐Temperature‐Crystallinity‐Superposition

Carotenuto

Grassia

Paduano

et al. 2019

Polymer Engineering & Sci

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Ethylene vinyl acetate (EVA) is a random copolymer of ethylene and varying amounts of vinyl acetate that interfere with poly‐ethylene chain packing reducing crystallinity, thus improving transparency and lowering the melting temperature to 40°C–60°C. The material viscoelastic properties in its working conditions may thus depend on the crystallinity degree. The crystallization process is here rheologically studied in non‐isothermal conditions and the frequency spectra are measured at different temperatures to investigate the viscoelasticity of EVA. Coupling the crystallization kinetics and the viscoelastic spectra at different temperatures, that is, at different degree of crystallinity, we here determine two independent shift factors, one for the time‐crystallinity shift, the other for the time‐temperature shift, so to propose a new time‐temperature‐crystallinity‐superposition to reconcile all the data on a single master curve. In this way, the experimentally observable frequency range has been widened significantly so to detect all the relaxation times of the material from the shortest to the largest ones. POLYM. ENG. SCI., 59:2550–2556, 2019. © 2019 Society of Plastics Engineers

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“…So far, it has been assumed that the suspension microstructure depends on the strain amplitude (γ 0 ) and strain history (γ tot ) in OS, and rate dependence (if any) is manifested in both SS and OS. However, recent experiments challenge this assumption and demonstrate a frequency (ω)-dependent rheology in OS in the absence of any rate-dependence in SS [8][9][10]. These authors demonstrate that, in OS, the suspension viscosity only depends on the maximum shear rate (γ 0 ω) and that data taken at different volume fractions (φ) can be rescaled on a single master curve, so to highlight a universal behavior of these materials.…”

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confidence: 99%

Irreversibility and rate dependence in sheared adhesive suspensions

Ge¹,

Martone²,

Brandt³

et al. 2021

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Recent experiments report that slowly-sheared noncolloidal particle suspensions can exhibit unexpected rate(ω)-dependent complex viscosities in oscillatory shear, despite a constant relative viscosity in steady shear. Using a minimal hydrodynamic model, we show that a weak interparticle attraction reproduces this behavior. At volume fractions φ = 20 ∼ 50%, the complex viscosities in both experiments and simulations display power-law reductions in shear, with a φ-dependent exponent maximum at φ = 40%, resulting from the interplay between hydrodynamic, collision and adhesive interactions. Furthermore, this rate dependence is accompanied by diverging particle diffusivities and pronounced cluster formations even at small oscillation amplitudes γ0. Previous studies established that suspensions transition from reversible absorbing states to irreversible diffusing states when γ0 exceeds a φ-dependent critical value γ c 0,φ . Here, we show that a second transition to irreversibility occurs below an ω-dependent critical amplitude, γ c 0,ω ≤ γ c 0,φ , in the presence of weak attractions.

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Dependence of suspension complex viscosity on frequency: Strain-controlled vs. stress-controlled tests

Cited by 4 publications

References 24 publications

Weakly adhesive suspension shows rate-dependence in oscillatory but not steady shear flows

Weakly adhesive suspension shows rate-dependence in oscillatory but not steady shear flows

Non‐Isothermal Crystallization Kinetics of an Ethylene‐Vinyl‐Acetate. II. Time‐Temperature‐Crystallinity‐Superposition

Irreversibility and rate dependence in sheared adhesive suspensions

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