emulsions and creams

A dispersion of two immiscible liquids, one dispersed as droplets within the other.

The substance being dispersed as droplets in an emulsion.

The substance in which the droplets of the internal phase are dispersed in.

The tendency of an emulsion to separate over time, with the internal phase separating from the continuous phase.

The increase in surface area between two immiscible liquids when they are emulsified.

The force that resists the mixing of two immiscible liquids.

A measure of the stability of an emulsion over a period of time.

The tendency of an emulsion to separate due to the thermodynamic properties of the system. This is related to the increase in surface area and interfacial tension during emulsification.

The energy required to create an emulsion with a specific droplet size. It is measured in Joules per week (J/WEEK).

A type of instability in emulsions that occurs when dispersed particles move within the continuous phase due to differences in density.

A process of kinetic instability where dispersed particles, less dense than the continuous phase, rise to the surface.

A process of kinetic instability where dispersed particles, denser than the continuous phase, settle to the bottom.

A law that describes the rate of sedimentation or creaming based on particle size, density difference, and viscosity.

Larger particles settle or rise faster due to gravity.

A smaller density difference between the dispersed and continuous phases leads to slower sedimentation or creaming.

A higher viscosity of the continuous phase slows down sedimentation or creaming.

A phenomenon where droplets in a colloid collide and join together, forming larger droplets, leading to a decrease in overall surface area.

A process where droplets in a colloid collide and associate with each other, moving together as a group, but their individual surface areas remain unchanged.

The process by which smaller droplets in a dispersion transfer their molecules to larger droplets through the continuous phase, driven by the difference in internal pressure between droplets of different sizes.

A surface-active ingredient (surfactant) that migrates to the interface between two phases, reducing interfacial tension and creating repulsive forces between the dispersed particles.

The ability of an emulsifier to surround dispersed particles with a physical barrier that prevents them from colliding and coalescing. This usually involves extending into the continuous phase, creating a 'shield' around each particle.

The ability of an emulsifier to create an electrical charge on the surface of each dispersed particle, creating repulsive forces that hinder coalescence and flocculation.

The tendency of a system to resist changes in its surface area. It is influenced by the type of molecules involved and the temperature.

As viscosity increases, the rate of creaming or sedimentation decreases, because the viscous fluid hinders the movement of dispersed particles.

The electrical potential that exists between the surface of a particle and the surrounding liquid, influencing the stability of a colloidal system.

The diffuse layer surrounding a charged particle in a liquid is constantly moving, creating a slipping plane which separates the bound layer from the diffuse layer. The Zeta Potential is a measure of the electric potential at this slipping plane.

A system is considered colloidally stable when particles repel each other enough to remain dispersed in the liquid. This typically happens when the Zeta Potential is above ±30 mV.

When the Zeta Potential is below ±30 mV, there is not enough repulsion between particles, leading to them clumping together and causing instability in the system.

Zeta potential only measures stability related to particle aggregation, such as flocculation and coalescence. It doesn't consider other factors like sedimentation.

The viscosity of an emulsion is directly proportional to the volume fraction of the dispersed phase. Larger volume fractions result in greater viscosity.

The phase volume (φ) is the percentage volume of the dispersed phase in an emulsion. This value is key in understanding whether the emulsion is water-in-oil or oil-in-water.

The Bancroft Rule predicts the type of emulsion based on the emulsifier's solubility. The emulsifier is more soluble in the continuous phase.

A surfactant mixture with both high and low HLB values can create a more stable emulsion compared to a single surfactant.

The HLB of a surfactant mixture can be calculated using the weighted average of the HLB values of the individual surfactants.

The substance being dispersed as droplets in an emulsion.

The substance in which the droplets of the internal phase are dispersed.

The concentration at which the adsorbed monolayer becomes saturated with surfactant molecules. Any additional surfactant molecules will form micelles.

Spherical aggregates of surfactant molecules in an aqueous solution.

Emulsifying agent, which stabilizes the mixture by reducing interfacial tension.

Determines whether the emulsion is oil-in-water (o/w) or water-in-oil (w/o).

A general principle of emulsion stability where smaller droplets are more stable, as they have a larger surface area-to-volume ratio.