Abstract: The coexistence curves of three pseudobinary microemulsion systems, consisting of surfactant, water and n-alkane, were determined by measurements of refractive index. The critical exponent β was deduced precisely from coexistence curves, which are consistent with the 3D-Ising exponent when the temperatures approach to the critical points. The experimental results also indicate that the critical amplitude scaling laws for chain molecular solutions are valid for these microemulsion systems.

Key words: Microemulsion, Critical phenomina, Coexistance curves, Scaling laws