1998 Volume 23 Issue 3 Pages 104-111
When the volume fraction of emulsion droplets exceed 0.74 as a closest-packing ratio for sphere, the droplets become the polyhedral shape rather than a spherical one. These emulsions are called HIPRE or highly concentrated emulsions. Since the HIPRE with the extreme high volume fraction of the dispersed phase shows visco-elastic and sometimes translucent, they are also refered to as “gel-emulsions”.
The type of gel emulsion formed in a given system depends mainly on the hydrophile-lipophile balance (HLB) of the surfactant. We describe the correlations between the nature of surfactant (HLB) and the emulsions types in a polyoxyethylene-type nonionic surfactant systems. The structure of the contineous phase in HIPREs is also mentioned.
The stability of W/O type HIPREs is enhanced by the addition of inorganic salts or some amphiliphiles such as monoglycerides and lecitions which produce a bilayer in water.
The two new techiniques to produce HIPREs are over-viewed.
