The influence of an ionic surfactant on different phases of the system with a non ionic surfactant base

The phase diagrams have been determined by isotherm method. The main obtained results which concern the influence of low quantity of an ionic surfactant on the phase diagrams are as follows: vast and stabilisation of iso trope zone in the system studied. the structural study of the water(C sup 1 sup 2 O sup 6 + 1.5% DSD) decan system shows that the crystalline zones are constituted with lamellar, cubic and direct hexagonal structures at 30 sup o sup . the structural parameters are determined by x-ray diffraction with small angles technique. The study of different zones allows to explain the conformational evolution of chain surfactant. (author)