COMPARISON OF MOLECULAR-WEIGHT DISTRIBUTIONS OF CORBETT ASPHALT FRACTIONS BY GEL-PERMEATION CHROMATOGRAPHY

Accurate molecular weight distributions are essential to the determina tion of the molecular structures of asphalt. Due to molecular complexi ty and interaction among the molecules of asphalt, precise measurement for the molecular weights of asphalt can not be achieved. In order to minimize the interactions of asphaltic materials, a petroleum asphalt sample was separated into saturates, naphthalene aromatics, polar aro matics, and asphaltenes. These Corbett fractions were then analyzed by gel permeation chromatography against nondispersive polystyrene stand ards. The molecular weights and the molecular size profiles were obtai ned. Among these Corbett fractions, naphthalene aromatics have the low est number average molecular weight; saturates have the lowest weight average molecular weight and dispersity; and asphaltenes have the high est number and weight average molecular weights and dispersity.