Hydrophilic-Lipophilic Balance of Emulsifers and Methods for Determination the Emulsion Systems Stability

An emulsion mixture system (usually water, oil and emulsifer) consists of two immiscible phases, the dispersed phase and the dispersion medium (dispersant-continuous). Due to their specifc rheological and physical-chemical properties, emulsions are commonly used in different industries such as cosmetics-pharmaceuticals, food and destruction (road construction, building destruction, etc.). One of the important requirements is appropriate stability of the emulsions over a certain period of time. Emulsions are thermodynamically unstable and several factors affect their instability including the variables of production process and storage conditions. Therefore, emulsifers are suitable to exhibit long-term stability and their performance can be determined by identifying the hydrophilic-lipophilic balance (HLB) characteristic in these compounds. HLB value is a number which is given by the emulsifer to indicate the hydrophilic and lipophilic tendencies of the material. The present work introduces the concept of HLB and methods for determination this character in various ionic and nonionic emulsifers. Considering the relation of the emulsifer HLB to its stability, different methods for evaluation the emulsions stabilities are discussed.