The characteristics of polar molecule ER fluids and a new type of polar molecule ER fluid

Abstract

Electrorheological (ER) fluid is usually prepared by suspending the particles into dielectric oil. Recently developed polar molecule dominated ER (PM-ER) fluid is consisted of solid particles with polar molecules coating or adsorbing on their surfaces, which is denoted as PM(S)-ER fluid. We have reviewed the main characteristics of PM(S)-ER fluid and explained some observed phenomena. However the lifetime of PM(S)-ER fluid in practical applications is too short because of the friction loss of the polar molecules on the particles. In order to improve the lifetime of ER fluid a new type PM-ER fluid denoted as PM(L)-ER fluid has been developed by dissolving polar molecules into oil instead of adsorbing on the particles. The lifetime of PM(L)-ER fluid is 5 times longer than that of PM(S)-ER fluid, while the shear stress keeps high enough. The manufacture procedure of PM (L)-ER fluid is simple, in addition, the performance and repeatability of the material are easily controlled.