Atomic Force Microscopy Investigation of SHRP Asphalts

摘要

Most asphalts (bitumens) are residua from the distillation of petroleum. Petroleum residua consist of a very large number of different organic compound types. These compound types vary greatly in polarity, from non-polar hydrocarbon waxes to aromatic, heteroatom-containing molecules. At the extremes of polarity, the compound types are immiscible. It has been suggested that the more polar constituents of petroleum residua form extensive molecular associations, involving stacking of individual aromatic sheets (1), hydrogen bonding, and other polar forces. The molecular associations are believed to be dispersed in a relatively non-polar solvent phase and are stabilized by molecules of intermediate polarity. The size of the molecular associations, and their interaction with each other and with solvent, are believed to determine many of the interesting physicochemical properties of asphalts. Thus, asphalts should be interesting subjects for study by AFM. Any micro-heterogenieties should be detectable if the above model, often referred to as the microstructural model, is valid.