Primary aggregation of asphaltene in solutions gives rise to 20 � nano-aggregates whose internal part is mostly aromatic whereas peripheral counterpart is rather aliphatic (1). The small angle neutron or X-Ray scattering (SAN(X)S) response gives much larger sizes (50-100 �). A structural model including these two typical sizes, namely a mass fractal model (cluster of nano-aggregates) allows viscosity solutions to be fully predicted (2).Taking advantage of complementary properties of neutrons and X-Ray with respect to scattering length density (SLD), we focus on small length scale of SAN(X)S curves relative to nano-aggregate structure. The core-shell cylinder form factor (Rcore =12, Rshell=6, Hcylinder=10 �) allows to fit both curves. The core and shell SLD values are found consistent with respectively aromatic and aliphatic compositions of asphaltene. Relevance of this model in terms of shape, dimensions, polydispersity, mass, aggregation number, diffusion coefficient and its implication on asphaltene solution properties will be discussed.

Insight into asphaltene nano-aggregate structure inferred by small angle neutron and X-ray scattering

240th National Meeting (2010)

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