Grupo de Reologia 
 Sistemas Organizados

Prof. Dra. Maria Regina Alcantara
FONE/FAX: +55 011 3091-2054


Lyotropic Liquid Crystals,  nematics and cholesteric.
Magnetorheological Fluids
Optical Microscopy under polarized light.
Nuclear Magnetic Resonance of organized systems, particularly deuterium, sodium and cesium  NMR.

            The rheological properties of lyotropic liquid crystals are often affected by their mechanical history, which may result in a modification of the microscopic structure of the material. Shear induced transitions were observed in concentrated solutions at defined salt content, indicating that the micellar size is affected by the flow. The anisotropic rheological behavior of lyomesophases has been studied in recent years by means of oscillating and non-oscillating rheological techniques, especially using the cone-and-plate geometries. The rheological parameters have been used to understand the spatial arrangement of the system constituent units and the way they change their order near the transition regions. Results published by our laboratory indicated that these systems are pseudoplastic and are characterized by a complicated transient response, either rheopexic or thixotropic, depending on whether the micelles are cylindrical or discotic, respectively.  Additionaly  our group has also been interested by the study of the rheology of magnetorheological fluids  based on carbonyl iron powders .
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