Macrostructure and rheological properties of chemically modified residues and bitumens

Rheological and X-ray scattering techniques were applied to investigate how the addition of phosphorus compounds to a refinery vacuum residue (Safaniy a) modifies its macroscopic behavior. The modified vacuum residue has a col loidal structure different from the original product. Rheological data show the more "gellike" nature of the modified sample in the temperature range from 0 to 40 degrees C. Its higher polydispersity and lower fractal dimensi on D-f also indicate that a shift toward a more gellike state occurs. The m odified sample flow properties appear to be strongly dependent on the chemi cal and structural modifications of the single separated fractions. Compare d to the strong modifications involving the asphaltene fraction, the change s which occur to the resin fraction properties are less important.