Non-linear viscoelasticity and temporal behavior of typical yield stress fluids: Carbopol, Xanthan and Ketchup

• Published in: Rheologica acta 2010-03, Vol.49 (3), p.305-314
• Main Authors: Benmouffok-Benbelkacem, G., Caton, F., Baravian, C., Skali-Lami, S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and medical sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Complex Fluids and Microfluidics; Cross-disciplinary physics: materials science; rheology; Deformation; material flow; Elasticity; Exact sciences and technology; Fluid dynamics; Fluids; Food industries; Food Science; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); Materials Science; Mechanical Engineering; Non-newtonian fluid flows; Nonlinear viscoelasticity; Original Contribution; Physical properties; Physics; Polymer industry, paints, wood; Polymer Sciences; Properties and testing; Rheological properties; Rheology; Soft and Granular Matter; Technology of polymers; Viscoelasticity; Xanthan; Yield strength; Yield stress
• ISSN: 0035-4511; 1435-1528
• DOI: 10.1007/s00397-010-0430-4

The viscoelastic properties of yield stress fluids are difficult to measure outside the linear viscoelastic regime, in particular above their yield stress. These properties are investigated for several common yield stress fluids using inertio-elastic oscillations. From this coupling between the instrument’s inertia and the viscoelasticity of the materials, the complete simple shear rheology can be determined, including viscoelasticity under flow. Findings show that the tested materials have an almost constant elasticity below and above the yield stress, even for applied stresses several times larger than the yield stress. Moreover, the temporal behavior of the materials is unambiguously determined. Concentrated Xanthan is shown to be thixotropic, while Ketchup mainly shows retarded viscoelasticity. Carbopol does not show long-term temporal dependance but apparently exhibits fracturation.