Procedures for DSC analysis of percolative microemulsions

In this paper we report about the procedure for investigating the thermal p roperties of three-component water-in-oil microemulsions exhibiting a perco lative behavior. The thermal properties of these highly disperse systems ar e analyzed both on freezing the liquid samples and upon their melting. A th ermal cycle suitable for evidencing the higher order phase transition at th e percolative threshold temperature is presented. Since the latter transiti on was found to depend on the system's thermal history, a modification of t he DSC set up is described that allows the refilling of the liquid nitrogen Dewar without requiring the removal of any of the instrument parts and ena bles to maintain the calibration assessment through long time lasting measu ring runs. The change in the specific heat, at constant pressure, at the pe rcolation transition was evaluated. The thermal hystheresis associated with the transition is also discussed. (C) 2000 Elsevier Science B.V. All right s reserved.