Electrorheological Properties of Suspensions Prepared from Polystyrene- Block- Polyisoprene Copolymer

Authors : Mustafa YAVUZ

Pages : 19-32

View : 14 | Download : 5

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Considerable scientific and industrial interest is currently being focused on a class of materials known as electrorheological insert ignore into journalissuearticles values(ER); fluids, which display remarkable rheological behaviour, being able to convert rapidly and repeatedly from a liquid to solid when an electric field insert ignore into journalissuearticles values(E); is applied or removed. In this article, the synthesis, characterization, partial hydrolysis and ER properties of polystyrene- block}-polyisoprene copolymer insert ignore into journalissuearticles values(COP); were investigated. The block copolymer was characterized by GPC, viscosity measurements, 1 H-NMR and FTIR spectroscopies, particle size measurements, and elemental analysis. The polystyrene block of the copolymer was partially hydrolyzed by a series of chemical reactions and then converted to a lithium salt by washing with a lithium hydroxide solution. Colloidal suspensions of this polymeric salt were prepared in silicone oil, at a series of concentrations insert ignore into journalissuearticles values(5-33% m/m);. Colloidal stabilities of these suspensions were determined at 20oC and 80oC. Flow times of suspensions were measured under no electric field insert ignore into journalissuearticles values(E = 0); , and under an applied electric field insert ignore into journalissuearticles values(E \neq 0); , and ER activity was observed. Further, the effects of solid particle concentration, shear rate insert ignore into journalissuearticles values( \dot{g} );, electric field strength, addition of a polar promoter and high temperature on ER activities of colloidal suspensions were investigated, and excess shear stresses were determined.
Keywords : Electrorheological fluids, polystyrene block polyisoprene copolymer, colloidal dispersions