Fabrication and electro-responsive electrorheological characteristics of rice husk-based nanosilica suspension

Rice husk-based nano-sized silica particles were prepared using both acid and thermal treatment methods for applications to electro-responsive electrorheological (ER) fluids when dispersed in silicone oil. The morphology of the nano-sized silica particles was observed by scanning electron microscopy, and their chemical structure and thermal stability were examined by Fourier-transform infrared spectroscope and thermo-gravimetric analysis, respectively. The ER properties of the nano-sized silica particle-based ER suspension was investigated using a rotation rheometer under various electric field strengths, showing a conduction mechanism with a slope of 1.5 for a plot of the yield stress versus the applied electric field strength. In addition, its shear stresses increased with increased electric field strengths along with ER efficiency and became stable over the entire shear rate range when the electric field reached 2.0 kV/mm. Typical solid-like behaviors of the ER suspension was also confirmed by both higher storage moduli than the loss moduli and shear relaxation modulus property. © 2018 Taiwan Institute of Chemical Engineers