(73g) The Role of Deformability in Determining the Structural and Mechanical Properties of Bubbles and Emulsions

Boromand, A. - Presenter, Yale University
We perform computational studies of jammed particle packings in two dimensions undergoing
isotropic compression using the well-characterized soft particle (SP) model and the deformable
particle (DP) model that we developed for compressed bubbles and emulsions. In the SP model,
circular particles are allowed to overlap, generating purely repulsive forces. In the DP model,
particles minimize their perimeter, while deforming at fixed area to avoid overlap during compression. We directly compare the structural and mechanical properties of jammed particle packings
generated using the SP and DP models as a function of the true packing fraction ρ, instead of
the reduced number density φ. We show that near jamming onset the excess contact number
∆z = z−zJ and shear modulus G scale as ∆ρ0.5
in the large system limit for both the SP and DP
models, where ∆ρ = ρ − ρJ and zJ ≈ 4 and ρJ ≈ 0.842 are the values at jamming onset. ∆z and
G for the SP and DP models begin to differ for ρ ≈ 0.88. In this regime, ∆z ∼ G can be described
by a sum of two power-laws in ∆ρ, i.e. ∆z ∼ G ∼ C0∆ρ0.5 +C1∆ρ1.0
to lowest order. We show that the ratio C1/C0 is much larger for the DP model compared to to that for the SP model. We
also characterize the void space in jammed packings as a function of ρ. We find that, unlike the SP model, the DP model is able to describe the formation of Plateau borders as the system approaches ρ = 1. We further show that the results for z and the shape factor A versus ρ for the DP model agree with recent experimental studies of compressed foams and emulsions.