Electrorheological Properties of Polypyrrole and its Composite ER Fluids

Electrorheological Properties of Polypyrrole and its Composite ER Fluids

Electrorheological (ER) fluids are suspensions of polarizable nonconducting or semiconducting particles in a nonconducting continuous phase of low relative polarizability. In the absence of an electric field, they have the properties of suspensions of neutral solid particles. Upon the application of an electric field, an organized structure of particles is formed and the ER fluids exhibit a remarkable change in rheological properties, including a drastic increase in apparent viscosity as well as yield stress. Various mechanisms have been proposed to explain the ER behavior to understand the ER behaviors and design effective ER fluids. Polypyrrole (PPy) is one of the most promising semiconducting polymers because it has higher conductivity and environmental stability than many other semiconducting polymers. PPy and its composites have been extensively used as ER materials and their ER fluids showed promising ER responses. ER properties of PPy based ER fluids (PPy, PPy copolymer, PPy coated particles, and PPy nanocomposites, etc.) and the ER behaviors of PPy based ER fluids such as shear, yield, and transient stress behavior and additive effect are reviewed.

Electrorheological (ER) fluids are suspensions of polarizable nonconducting or semiconducting particles in a nonconducting continuous phase of low relative polarizability. In the absence of an electric field, they have the properties of suspensions of neutral solid particles. Upon the application of an electric field, an organized structure of particles is formed and the ER fluids exhibit a remarkable change in rheological properties, including a drastic increase in apparent viscosity as well as yield stress. Various mechanisms have been proposed to explain the ER behavior to understand the ER behaviors and design effective ER fluids. Polypyrrole (PPy) is one of the most promising semiconducting polymers because it has higher conductivity and environmental stability than many other semiconducting polymers. PPy and its composites have been extensively used as ER materials and their ER fluids showed promising ER responses. ER properties of PPy based ER fluids (PPy, PPy copolymer, PPy coated particles, and PPy nanocomposites, etc.) and the ER behaviors of PPy based ER fluids such as shear, yield, and transient stress behavior and additive effect are reviewed.