Theoretical emulsification Flashcards
what is a single emulsion?
2 component system
o/w or w/o
what is a double emulsion?
3 component system
w/o/w or o/w/o
what does an emulsifier do?
forms film around droplets and stabilises by lowering interfacial energy
what does a viscosity enhancer do?
inhibits droplet diffusion and prevents coalescence
what does attraction promote?
droplet consolidation
instability
what does repulsion promote?
droplet separation
stability
DLVO theory?
2 forces impact stability
electrical repulsion
Van der Waals attraction
what is sedimentation?
Particles (droplets) sink in continuous phase under opposing forces.
what promotes sedimentation?
larger droplets
greater density difference
lower viscosity
what promotes sedimentation?
larger droplets
greater density difference
lower viscosity
what does stokes law state?
expresses the drag force resisting the fall of small spherical particles through a fluid medium
2 factors that determine emulsion type?
phase volume ratio
Bancroft rule
what is Bancroft’s rule?
The phase in which the emulsifier is more
soluble is the continuous phase
bulker proportion of emulsifier faces outwards
what is hydrophile-lipophile balance (HLB)?
scale indicating overall hydrophilicity/lipophilicity of an emulsifier
what does a low HLB indicate?
more lipophilic emulsifier
