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Yielding and Flow in Adhesive and Nonadhesive Concentrated Emulsions

2006; American Physical Society; Volume: 96; Issue: 13 Linguagem: Inglês

10.1103/physrevlett.96.138302

1092-0145

Lydiane Bécu, Sébastien Manneville, Annie Colin,

Pickering emulsions and particle stabilization

The nonlinear rheological response of soft glassy materials is addressed experimentally by focusing on concentrated emulsions where interdroplet attraction is tuned through varying the surfactant content. Velocity profiles are recorded using ultrasonic velocimetry simultaneously to global rheological data in the Couette geometry. Our data show that nonadhesive and adhesive emulsions have radically different flow behaviors in the vicinity of yielding: while the flow remains homogeneous in the nonadhesive emulsion and the Herschel-Bulkley model for a yield stress fluid describes the data very accurately, the adhesive system displays shear localization and does not follow a simple constitutive equation, suggesting that the mechanisms involved in yielding transitions are not universal.