AGGREGATION OF ASPHALTENES AS DETERMINED BY CALORIMETRY

The critical micelle concentrations (CMCs) of petroleum asphaltenes were determined at 25°C in mixtures of n-alkanes and toluene using a calorimetric titration method. CMC was correlated to the Hildebrand solubility parameter. CMC determinations in polar solvents showed that the correlation is valid only for the alkane-toluene system. The role of resins in formation of the micelle was investigated, showing that resins may lead to formation of a different kind of micelle that may be more stable toward precipitation. The resins did not act as cosolvents in the asphaltic solution. © 1991.