Additional information
Background
An emulsion is a mixture in which two immiscible substances, like oil and water, stay mixed together with the help of a third substance called an emulsifier. An invert emulsion or “backwards” emulsion refers to an emulsion in which oil is the continuous or external phase and water is the dispersed or internal phase so that, in a given period of time after mixing oil and water phases with the help of an emulsifier, the emulsion may break down and may return gradually to the oil and water split. Therefore, there is a crucial need for improving the performance of these emulsions by developing effective techniques of mixing to increase the homogeneity of the emulsion and finding new and effective emulsifiers to increase the emulsion stability for long time.
Invert emulsions (water-in-oil type) are the most frequently used type of invert emulsions. They are mainly consisting of two liquid phases: dispersed phase (water) and continuous phase (oil). Emulsifiers that are introduced into these emulsions are usually included in the ingredients of the two phases before mixing them, they might be oil-soluble emulsifiers and water soluble emulsifiers. The water phase introduced into this emulsion is usually homogenized with oil phase at a high speed (20,000 rpm for 1.5 min using a homogenizer), thus the smaller water droplets in the final emulsion are completely surrounded by the larger oil droplets to produce water in oil emulsion. Therefore, during application, the oil droplets prevent the water droplets from evaporation especially at hot and dry conditions.