TEMPERATURE-DEPENDENCE OF THE DENSITY OF AN IONIC MICELLAR SYSTEM NEAR THE CRITICAL-POINT

The density of the system dodecylammonium chloride + water + KCI has b een studied as a function of temperature and surfactant composition fo r two different concentrations of KCI. The data of the critical sample s can be described using scaling laws and the 3D Ising value for the c ritical exponent alpha. The range of validity of simple scaling for th e density is found to be larger than for the order parameter. When com bined with previously reported data, the present results confirm the v alidity of the two-scale factor universality hypothesis in this ionic micellar system. The results obtained for off-critical compositions ha ve been found to be compatible with predictions of the so-called linea r model.