Magnetic viscoelastic behavior in a colloidal ferrofluid
| Autor: | R. Peredo-Ortíz, M. Hernández-Contreras, R. Hernández-Gómez |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Physics
Ferrofluid 010304 chemical physics Transport coefficient General Physics and Astronomy Mechanics 010402 general chemistry 01 natural sciences Viscoelasticity 0104 chemical sciences Condensed Matter::Soft Condensed Matter Langevin equation Viscosity Einstein relation 0103 physical sciences Relaxation (physics) Physical and Theoretical Chemistry Rotational Brownian motion |
| Zdroj: | The Journal of Chemical Physics. 153:184903 |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/5.0021186 |
| Popis: | Based on the stochastic Langevin equation, we derived the total friction experienced by a tracer particle diffusing in thermally equilibrated colloidal magnetic fluids. This transport property leads to new expressions for its long-time diffusion coefficients, which satisfy an Einstein relation with the frictions of its translational and rotational Brownian motion. Further use of the nano-rheology theory allowed us to derive also the viscoelastic modulus of the colloid from such a property. The temporal relaxation of the viscoelasticity and transport coefficient turns out to be governed by the intermediate scattering function of the colloid. We derived an explicit formula for this evolution function within a hydrodynamic theory to include rotational degrees of freedom of the particles. In the limit of short frequencies, the viscous moduli render a new expression for the static viscosity. We found that its comparison with known experiments, at low and high concentration of ferroparticles in magnetite ferrofluids, is fair. However, comparing the predicted viscoelastic moduli with computer simulations as a function of frequency yields poor agreement. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|