Experimental study of forces between quasi-two-dimensional emulsion droplets near jamming

We experimentally study the jamming of quasi-two-dimensional emulsions. Our\nexperiments consist of oil-in-water emulsion droplets confined between two\nparallel plates. From the droplet outlines, we can determine the forces between\nevery droplet pair to within 8% over a wide range of area fractions $\\phi$. We\nstudy three bidisperse samples that jam at area fractions $\\phi_c \\approx\n0.86$. Our data show that for $\\phi > \\phi_c$, the contact numbers and pressure\nhave power-law dependence on $\\phi-\\phi_c$ in agreement with the critical\nscaling found in numerical simulations. Furthermore, we see a link between the\ninterparticle force law and the exponent for the pressure scaling, supporting\nprior computational observations. We also observe linear-like force chains\n(chains of large inter-droplet forces) that extend over 10 particle lengths,\nand examine the origin of their linearity. We find that the relative\norientation of large force segments are random and that the tendency for force\nchains to be linear is not due to correlations in the direction of neighboring\nlarge forces, but instead occurs because the directions are biased towards\nbeing linear to balance the forces on each droplet.\n