Properties of aniline-modified strontium titanyl oxalate-based electrorheological suspension

Abstract

Aniline-modified strontium titanyl oxalate (STO) particles were fabricated with a precipitation method. The structures of the particles were analyzed by x-ray diffraction analyses, Fourier transform infrared spectrometry and thermogravimetric analysis. Scanning electron microscopy was used to analyze the morphology of the particles. The results indicate chemical bonds are formed between STO and aniline. By tuning the molar ratio of aniline to Ti, the morphology of the aniline-modified STO particles can be sphere, polyhedron and a mixture composed of clusters of nano particles and micro rod-like particles. Electrorheological (ER) properties, temperature effect, thixotropy and sedimentation stability of the ER fluids based on the pure STO and the aniline-modified STO were tested. The results indicate all the properties strongly depend on the content of the aniline during the fabrication process of the particles. The ER fluid with a molar ratio of aniline/Ti of 2 presents the highest shear stress, yield stress, leak current density and the most stable ER behavior at changing temperatures. The reason is the particles have polyhedron morphology and absorbed polar aniline molecules. Because of the stable space grid structure formed by the particles with a molar ratio of aniline/Ti of 3, the ER fluid exhibits better thixotropy and sedimentation stability than the others.