Properties of a two-dimensional asphaltene network at the water-cyclohexane interface deduced from dynamic tensiometry

Patrick Bouriat (1) , N.E. Kerri , Alain Graciaa (1) , Jean Lachaise (1)

1 TEFC - Thermodynamique et Energétique des fluides complexes

Static and dynamic tensiometries show that a newly prepared water/asphaltenated cyclohexane interface behaves as expected: the mean area occupied per asphaltene molecule is 2 nm2, and variations of interfacial tension and dilatational elastic modulus with time indicate that equilibrium is reached more slowly than that for usual surfactants. The use of the time/temperature superposition principle allows a detailed rheological study of a 2 day old interface of the same type which has reached equilibrium. It is found that the two-dimensional asphaltene network exhibits a glass transition zone, behaves as a gel near its gelation point, and is built by a universal process of aggregation.

Mots clés: Asphaltene networks; Dilatational elastic modulus; Dynamic tensiometry; Surface active molecules Engineering controlled terms: Elastic moduli; Gelation; Glass transition; Interfaces (materials); Surface active agents; Thermal effects; Viscoelasticity Engineering main heading: Binary mixtures PaperChem Variable: Glass Transition Temperature; Surfactants; Viscoelasticity

Domaines: Chimie-Physique [physics.chem-ph]

Patrick Bouriat, N.E. Kerri, Alain Graciaa, Jean Lachaise. Properties of a two-dimensional asphaltene network at the water-cyclohexane interface deduced from dynamic tensiometry. Langmuir, 2004, 20 (18), pp.7459-7464. ⟨10.1021/la049017b⟩. ⟨hal-00685725⟩