Yielding and flow of monodisperse emulsions

摘要: The authors have measured the yield transition of monodisperse emulsions as volume fraction, {phi}, and droplet radius, {alpha}, are varied. They study crossover from perturbative shear regime, which reflects linear viscoelastic properties, to steady nonlinear, plastic flow. For small oscillatory strains peak amplitude {gamma}, stress, {tau}, is linearly proportional {gamma}. As strain increased, stress becomes nonlinear in {gamma} at strain, {gamma}{sub y}. {phi} dependence y} independent {alpha} exhibits a minimum near critical {phi}{sub c} = 0.635, associated with random close packing spheres. show that {tau}{sub y}, increases dramatically fraction above c}; also scales Laplace pressure, {sigma}/{alpha}, where {sigma} interfacial tension. comparison, they determine over wide range rates, {dot {gamma}}. Below 0.70, flow homogeneous throughout sample, while for higher emulsion fractures resulting highly inhomogeneous along fracture plane. Above 0.58, amore » low rate plateau corresponds technique. Moreover, robust power law on {gamma}} exponents decreasing varying 2/3 {1/2}. colloidal glass transition, disappears entirely.« less