Abstract
Cetostearyl alcohol has been incorporated into cosmetic or pharmaceutial emulsions to give them an appropriate consistency and a long term stability. It is well known that cetostearyl alcohol forms a gel phase with a nonionic surfactant in an aqueous system, and the properties of the gel phase depend on several factors such as the ratio of fatty alcohols. The aim of the present Paper is to investigate the effect of the structural difference of the lipophilic part of surfactants on the stability of the gel phase in the nonionic surfactant / cetostearyl alcohol / water ternary systems using differential scanning calorimeter. It is concluded that the gel phase formed by the surfactant having the bended alkyl chain is more unstable than that formed by the case of the straight alkyl chain, and we discussed the reason why the former is more unstable after long term storage by means of the measurements of the ${\Delta}$H.