Petroleum macrostructure

The close interplay of analytical methods gives much additional information especially in those areas where the analyzed substances are very complex. Thus, while ultracentrifuge analyses for petroleum (32, 33, 34) gave much information, the broad approach used by others (35, 36, 37) involved x-ray scattering, infrared, NMR, oxidation rates, GPC, MS, pyrolysis, and vapor pressure osmometry (VPO) applied to macrostructures of asphaltic fractions. Molecular complexes substantially larger than the foregoing macrostructures are difficult to characterize by methods short of ozonolysis (38) and general pyrolysis (39). 

Macrostructure. Generally, petroleum-derived asphaltene is uniso-tropic in structure. It can be classified as a mesomorphic liquid, that is, many individually oriented clusters are suspended and randomly distributed within their lower molecular weight homologs (12). The individual clusters are... 

Table II. Some Commonly Used Structural Parameters for the Macrostructure of a Petroleum-Derived Asphaltene...

Figure 3. The general features of the macrostructure of petroleum-derived asphaltenes and related substances...

J.C. Ravey and D. Espinat Macrostructure of petroleum asphaltenes by small angle neutron scattering. Progr. Colloid, Polym. Sci. 81, 127-130 (1990). 

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