Experimental Study On Influence Of Liquid Phase On Properties Of Oxalate Group-modified Amorphous Titanium Oxide Nanoparticles-based Electrorheological Fluid

Electrorheological (ER) fluid is a suspension made of dielectric particles dispersing in an insulating liquid. The viscosity and yield stress of ER fluid can vary continuously, reversibly and rapidly as the change of applied electric field. Because of its special characteristics, the ER fluid can serve as an electrical-mechanical interface with potential applications in controllable clutches, dampers, valves, etc. ER fluids can be considered as a tow-phase system with liquid phase as a basic phase. It is no doubt that the dispersing liquid plays a important role in improving ER properties. Scholars focus on the development of different dispersing media, none has systematically investigated the role of the dispersing liquid. In order to find out the optimal liquid phase materials, the article dedicated to the research of the influence of liquid phase on properties of ER. This is to make up for the absence of the research of liquid phase and improve the ER properties with theoretical and practical significance.In this article Electrorheological (ER) fluids were fabricated by dispersing oxalate group-modified amorphous titanium oxide nanoparticles in silicone oil with different viscosity and different terminal groups (hydroxyl, hydrogen, and methyl) to study the influence of liquid phase on properties of electrorheological fluid. The study is divided into two parts:(1) Dimethyl silicone oil with different viscosity (10cSt,50cSt,100cSt,500cSt and1000cSt) were as the dispersion liquid. The yield stress, zero-field viscosity, ER efficiency, response time, and sedimentation stability were tested to find the influence of the viscosity of silicone oil on properties of ER fluids. The results indicate that the ER fluids based on the silicone oil with kinematic viscosity of50cSt presents the optimal ER efficiency, and the fluids based on the silicone oil with kinematic viscosity of100cSt shows the shortest response time and good sedimentation stability. The mechanism is the silicone oil with larger viscosity provides larger viscous force, but makes the nanoparticles easier to agglomerate. The microstructure observation of the ER fluids shows that higher viscosity of oil leads to form thicker column structure. Wettability experiments show that higher viscosity of oil leads to lower permeability. (2) Silicone oil with similar viscosity but different terminal groups (hydroxyl, hydrogen, and methyl) were as the dispersion liquid. The yield stress, zero-field viscosity, ER efficiency, leak current density, shear stability and sedimentation stability was tested to find the influence of the terminal group of silicone oil on properties of ER fluids. The results indicated that the ER fluids based on the silicone oil with polar terminated group presents improved yield stress, higher ER efficiency, and better sedimentation stability, but larger leakage current density, while the ER fluids based on the silicone oil with small terminated group presents higher yield stress, higher ER efficiency, and less leakage current density, but worse sedimentation stability. The microstructure observation of the ER fluids shows that silicone oil with hydroxyl terminated group forms thicker column structure than silicone oil with hydrogen terminated group and silicone oil with methyl terminated group.