ASPHALTENES IN POLAR-SOLVENTS

Various techniques were employed to study the colloidal properties of asphaltenes in solutions. Based on surface tension, viscosity, dielectric relaxation, conductivity, and small angle neutron scattering measurements, we have found that asphaltene molecules exhibit a strong propensity for self-association, and that these aggregates are approximately spherical in shape. Unlike micelles, these aggregates do not grow with increasing concentration. This is mainly due to packing constraints, resulting from the complicated molecular structure of asphaltenes. The conductivity and dielectric relaxation measurements suggest that the electron transformation between asphaltene molecules is the main mechanism in forming aggregates, but these aggregates do not percolate at either high concentration, or high temperature (60-degrees-C).