The electrorheological responses of suspensions of polypyrrole-coated polyethylene particles

Abstract

The electrorheological (ER) responses of polypyrrole (PPy)-coated polyethylene (PE) suspensions in mineral oil were investigated. PPy was coated on PE particles to enhance the particle polarization by increasing the particle surface conductivity, which would lead to an enhanced ER response. The ER response of the PPy-coated PE suspensions is greatly enhanced compared to that of the PE suspension. The dielectric properties of the corresponding suspensions show that the ER enhancement arises from the enhanced particle polarization. Various PPy-coated PE particles were synthesized by controlling the amount of pyrrole or FeCl3·6H20 during the pyrrole polymerization, and the ER responses of their suspensions were investigated. The ER response initially increases with the amount of pyrrole or FeCl3·6H20, passes through a maximum, and then decreases with the amount of pyrrole or FeCl3·6H20. The increase in the ER response with amount of pyrrole or FeCl3·6H20 is due to the enhanced particle polarization with the increased particle surface conductivity. The decrease in the ER response at large amounts of pyrrole or FeCl3·6H20 arises from the increased conduction between the PPy-coated PE particles. Poly(vinyl alcohol) was coated on the PPy-coated PE particles to restrict the increased conduction. The ER response is greatly enhanced by the poly(vinyl alcohol) coating on the PPy-coated PE particles, suggesting that the effective ER suspensions can be prepared by both enhancing the particle surface conductivity and restricting the increased conduction.