| Nano-scale solid particles have an affect on the stability of emulsion droplets but direct optical observation is impossible due to the particles' diminutive dimensions. In this study, silicon oil, water and glass beads were used to construct a solids-stabilized emulsion droplet model. Ground-based and reduced-gravity experiments with the model were performed and the model confirmed that particles that protrude from the droplets could form a physical barrier between the drops and prevent coalescence between two droplets. The model also showed that when hydrophobic beads were introduced from the water phase, additional energy is required to force the beads on to the interface. The beads' behaviour near the interface is consistent with fluid drainage (causes beads to stop on the interface before 'popping' forces (hold hydrophobic beads on water side of the interface) and line tension (prevents hydrophobic beads from crossing the interface), although surface heterogeneity cannot be completely ruled out. |
