β Scribed by Y.C. Liu; Eric Y. Sheu; S.H. Chen; D.A. Storm
No coin nor oath required. For personal study only.
Small-angle neutron scattering (SANS) was used to study the fractal structure of Ratawi petroleum asphaltenes in toluene. For analysis of the SANS data, the asphaltene aggregates are modelled as polydisperse fractal objects containing monodisperse asphaltene micelles as unit particles. This model is applicable to asphaltene concentrations of lo-80 wt%. The results show that the asphaltenes are well dispersed with a low agglomeration number when the concentration is 5 40%, and the fractal dimension is N 3.0. Above 40 wt%, large clusters start to form, and the fractal dimension decreases to a minimum of N 1.8 at 60 wt%. Above 60 wt% the average cluster size gradually decreases, while the fractal dimension increases, regaining N 3.0 at > 75 wt%. This is attributed to a phase inversion phenomenon. In addition, the clustering of asphaltene micelles is found to follow a reaction-limited aggregation process.
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