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Published on: September 30, 2014
Enhancement of electrorheological effect by particle-fluid interaction
F Aliotta1, P Calandra, M Pochylski
1CNR-Istituto per i Processi Chimico-Fisici, Viale Ferdinando Stagno d'Alcontres 37, I-98158 Messina, Italy. aliotta@ipcf.cnr.it
Summary
Electrorheological suspensions with titania nanoparticles in octanoic acid show a significantly larger electrorheologic effect. This is due to a molecular layer on particle surfaces, increasing effective particle size and volume fraction.
Area of Science:
- Materials Science
- Colloid Science
- Rheology
Background:
- Electrorheological (ER) suspensions change viscosity under an electric field.
- Understanding particle-fluid interactions is key to ER fluid performance.
Purpose of the Study:
- To investigate the influence of particle surface and host fluid interactions on ER suspensions.
- To explain the anomalously large ER effect observed in specific titania dispersions.
Main Methods:
- Comparing ER effects of nanosized titania in octanoic acid with micrometric titania and silica in silicone oil.
- Fitting experimental data with modified conductive models.
- Analyzing the role of surface molecular layers and particle deformation.
Main Results:
- Nanosized titania in octanoic acid exhibited an anomalously large ER effect.
- The effect is attributed to a thin layer of octanoic acid on titania surfaces, increasing effective particle radius and volume fraction.
- Deformation of this soft shell by Coulombic forces also contributes significantly.
Conclusions:
- The formation of a surface molecular layer is crucial for enhancing ER fluid performance.
- Tailoring particle size, surface chemistry, and shell properties can optimize ER fluids for specific applications.
- Further research into surface-induced effects can lead to advanced ER materials.
