The Preparation And Determination On The Superheat Limit Of Microemulsion

Pseudo-ternary phase diagrams in four-component systems of n-C7H16/n-C4H9OH/Span80+Tween80/H2O,km=0.5,1,2(km=w(alcohol)/w(surfactant));n-C7H16/i-C4H9OH/Span80+Tween80/H2O,km=0.5;n-C7H16/n-C4H9OH/CTAB/H2O,km=1;n-C7H16/n-C4H9OH/Span80+CTAB/H2O,km=1;n-C7H16/n-C4H9OH/Tween80+CTAB/H2O,km=1 are presented at 30℃ by electrical conductivity. An expected transparent water-in-oil (w/o) micro-emulsion was formed in these systems. On the basis of experimental data, for the micro-emulsion of nonionic surfactants, the size of w/o region minishes with increasing of km, and at the same km, it is obvious smaller than that of ionic surfactants. The electrical conductivities of above system measured by conductivity meter show that percolative conduction exists in both the micro-emulsion of nonionic surfactants and that of ionic surfactants, but they are different. In the system of nonionic surfactants, the electrical conductivity of the w/o micro-emulsion stabilizes before percolative conduction, whereas in the system of ionic surfactants, it increases with increasing of water contents to maximum, and then decreases to minimum, at which a liquid crystal phase forms and EM concentration (we, mass ratio) is about 0.30～0.75.The superheat limit temperatures of above systems except n-C7H16/n-C4H9OH/ Span80+Tween80/H2O (km=2) and n-C7H16/n-C4H9OH/ Tween80+CTAB/H2O (km=1) have been measured by using the column method, and for n-C4H9OH, n-C8H17OH systems, they were measured at the point that the ratio of emulsifier to oil is 0.4(we=0.4) and that of alcohol to surfactant is 0.5 (km=0.5). On the basis of experimental data, the superheat limit temperature of microemulsion increases with increasing of emulsifier concentration, and it stabilizes with increasing of water contents when alcohol and km are same. In addition, it ascends with increasing of the carbon number of unbranched alcohol.These data fill in the gaps in the field of data of superheat limit temperatures of microemulsion systems, and offer basal data for the burning of emulsificated fuel.