Abstract
Concentrated emulsions with volume fractions exceeding the critical value have diverse applications in foods, cosmetics, coatings, and pharmaceuticals. They have a jammed structure and tend to exhibit a solid-like behavior. Unfortunately, the mechanical properties of monodisperse concentrated emulsions are challenging to study by experiments or simulations because of thermodynamic instability and droplet coalescence. A mesoscopic simulation method is employed to study the mechanical properties of the concentrated emulsion. Knowledge of the microstructure and interdroplet interaction among monodisperse droplets is not a prerequisite. Effects of the volume fraction (ϕ), droplet diameter (D), and interfacial tension (σ) on Young’s modulus (E) and bulk modulus (K) are investigated systematically. For ϕ < ϕc, Young’s modulus is absent and the bulk modulus rises with increase ϕ. For ϕ > ϕc, both Young’s and bulk moduli are found to grow with increasing ϕ and σ. However, these solid-like properties become more prominent as D is decreased. On the basis of the interfacial energy per unit volume, our simulation results can be well represented by the relations E ∼ ϕ0.13(ϕ-ϕc)1.55(σ/D) and K ∼ ϕ1.06(ϕ-ϕc)0.15(σ/D). Moreover, the relationship for soft materials E = 3 K(1 − 2ν) is satisfied. The Poisson’s ratio (ν) is very close to 0.5 but still decreases slightly with increasing ϕ.
Published Version
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