Rheo-dielectric effect in liquid suspensions

Abstract

A rheo-dielectric effect, dielectrostriction, relates the polarizability of a material to its deformation. Stress, strain, strain rate or some combination of these parameters could be the state variables for a given material. The description of the dielectrostriction in isotropic materials involves two material coefficients. A key advantage of the presented experimental technique is the utilization of a single deformation mode, shear deformation, for two independent measurements of the material coefficients in liquid suspensions. The study is conducted with micro- and nano-sized alumina oxide (Al₂O₃) particles dispersed either in silicone oil (Newtonian fluid) or in liquid silicone elastomer (viscoelastic fluid). The dielectrostriction response of each suspension is compared with those of the corresponding base liquids. The selection of strain or stress as the state variable of deformation is discussed. Material coefficients for both the strain- and stress-based descriptions are presented for each system.

Keywords:

• micro- and nano-suspensions
• polarization
• rheo-dielectric relation
• suspension rheology
• dielectrostriction effect

Acknowledgements

The authors thank Professors Lih-Sheng Turng and Robert E. Rowlands from UW-Madison, and Professor Haimei Li of Zhengzhou University for helpful discussions. This work was supported in part by the National Science Foundation Grant #CMS-0437890 and Wisconsin Alumni Research Foundation. We also thank Michelle Schoenecker for technical assistance.