Phase transitions in ternary systems and oil-in-water emulsions containing cetrimide and fatty alcohols

Abstract

Differential scanning calorimetry (D.S.C.) was used to investigate phase transitions in stable and unstable emulsions prepared with cetrimide/fatty alcohols. Ternary systems, formed by interacting cetrimide and fatty alcohol in water and chosen to represent the continuous phases of the corresponding emulsions, were also investigated. Stability was followed using rheological techniques. The ternary systems prepared from each alcohol showed similar properties to the corresponding emulsions. All systems were semisolid immediately after preparation. Thus flow curves were in the form of anticlockwise hysteresis loops and apparent viscosities high. On storage, the cetostearyl alcohol systems remained semisolid and stable, whereas the pure alcohol systems became mobile and emulsions eventually separated. In unstable systems, flow curves changed and apparent viscosities reduced. The D.S.C. data for each ternary system gave similar transitions to those of the corresponding emulsion. In the stable cetostearyl alcohol ternary system and emulsion, two broad endotherms were present. These did not alter over the 30-day testing period. In contrast, the unstable pure alcohol ternary systems and emulsions, showed several endothermic transitions, which changed as systems aged and became mobile. The D.S.C. results correlated well with microscopic and rheological experiments from previous work. They imply that emulsion continuous phases, formed from the interaction of cetrimide and fatty alcohol in water can exist in several forms, each