Oscillatory Shear Rheology for Probing Nonlinear Viscoelasticity of Complex Fluids: Large Amplitude Oscillatory Shear

Rheology of peptide‐ and protein‐based physical hydrogels: Are everyday measurements just scratching the surface?

“…While steady‐state shear is used to observe the flow of hydrogels, LAOS measurements are instrumental in characterizing large, rapid material deformations and help offer a more complete perspective of soft material responses to processing. LAOS measurements and some typical rheological responses from complex fluids have been reviewed by Hyun et al and Deshpande et al In order to ascertain the strain and frequency windows in which the studied hydrogel behaves like a solid (i.e., measurements are performed in the LVR), the oscillatory strain sweep measurement and the frequency sweep measurement should be the first measurements to be carried out on a hydrogel during its rheological characterization. A precise idea of frequency and strain response is important since the values of G ′ and G ″ measured by the rheometer during an oscillatory time sweep measurement (e.g., during initial gelation or during rehealing after shear‐thin flow) will be at constant frequency and need to be at strains within the LVR.…”

“…Sometimes, a thorough understanding of the nonlinear rheological behavior of these materials is interesting and beneficial to further explore their use as injectable drug/cell delivery vehicles and load bearing biomaterials. Reviews of large amplitude oscillatory shear (LAOS) measurements (i.e., oscillatory application of strain outside of the LVR) and their utility in probing nonlinear (i.e., outside the LVR) viscoelastic properties of complex fluids such as polymer solutions and melts, emulsions, biological gels, and micellar solutions has been provided by Hyun et al, and Deshpande . Steady‐state shear treatment, the non‐oscillatory ‘spinning’ of the rheometer top plate at a specified rate, consequently applying strain that is far outside the LVR, is the other experimental rheological technique used to subject a hydrogel to shear treatment.…”

Rheological characterization of Poly(ethylene oxide) and carboxymethyl cellulose suspensions with added solids

“…Indeed, dynamic rheometry is an efficient tool to investigate the properties of food or polymer solutions with or without particles under conditions close to the atrest state, i.e. when small amplitude oscillatory shear are applied (Deshpande, 2010). Indeed, this allows the determination of the viscoelastic properties without the disruption of the internal structure of the sample.…”

“…Indeed, this allows the determination of the viscoelastic properties without the disruption of the internal structure of the sample. Under this condition, the sinusoidal stress applied to a non-Newtonian fluid sample can be represented as (Deshpande, 2010;Rao, 1999): s ¼ s 0 sinðutÞ (7) and the linear response of the solution in terms of strain can be monitored and written as…”

An adaptive parallel tempering method for the dynamic data‐driven parameter estimation of nonlinear models

“…This model also involves comparison to the equilibrium value of the structure parameter, based on current stress or shear rate, to calculate the new value. It uses the difference between current conditions and equilibrium conditions as the driving force to calculate the next value of structure parameter, modulus, viscosity, etc …”