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GresoGrupo de ReologiaemSistemas Organizados |
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Prof. Dra. Maria Regina Alcantara
E-MAIL: mralcant@iq.usp.br
FONE/FAX: +55 011 3091-2054
RESEARCH INTERESTS.
Lyotropic Liquid Crystals,
nematics
and cholesteric.
Rheology.
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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