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Rheology Of Foams And Highly Concentrated Emulsions: III. Static Shear Modulus
Published 1986 · Materials Science
Abstract The static shear modulus of a series of concentrated, well-characterized oil-in-water emulsions has been determined and is found to be accurately represented by G = 1.769 σ R 32 φ 1 3 (φ − 0.712) , where σ is the interfacial tension, R32 is the surface-volume mean drop radius, and φ is the volume fraction of the dispersed phase. The equation is believed to have universal applicability, and should be equally valid for foams, although the values of the numerical constants may depend slightly on the drop size distribution and the thickness of the aqueous films between the droplets. Older theories for the limiting case of φ ≈ 1 overpredict the modulus by a factor of exactly, or close to, 2. The source of this error may be traced to the underlying model, which does not meet the condition of mechanical equilibrium at the lines of intersection of the interdroplet films as the network is strained.