Resumo

MANERO, Octavio. Out of equilibrium phase transitions in complex fluids. Educ. quím [online]. 2011, vol.22, n.1, pp.28-31. ISSN 0187-893X.

In this work, various examples of the flow of complex fluids are briefly exposed, in which an induced phase transition occurs out of the thermodynamic equilibrium under the flow strength. The imposed flow generates molecular ordering along certain directions in systems such as micellar solutions, particle suspensions, emulsions, polymer solutions, and so on. This ordering process may also produce flow induced structures that under some conditions generate instabilities in the system. To recover the dynamic equilibrium, i.e., steady state, the system separates in two or various phases, each one with different molecular order. This process is analogous to an equilibrium phase transition, in which the order parameter in this case is proportional to the critical velocity gradients of the system.

Palavras-chave : complex fluids; non equilibrium phase transitions; rheology; rheological modeling; van der Waals.