Investigation of electrorheological properties of some copolymers and their industrial application

Electrorheological (ER) fluids display remarkable rheological behaviour, being able to convert rapidly and repeatedly from a fluid to a solid when an electric field is applied or removed. In this study, synthesis, characterization and ER properties of poIy(4-vinyl pyridine)/po!y(2-hydroxyethyI methacrylate), po!y(4- VP)/poly(HEMA), copolymers were investigated. The copolymers were synthesised by radicalic polymerization using K2S2O8 initiator. The polymers prepared were characterized by gel permeation chromatography, GPC, viscosity measurements, *H and 13C-NMR, FTTR spectroscopies, dynamic light scattering, (DLS), elemental analysis and end group analysis methods. The copolymers were partially hydrolyzed and washed with LiOH(aq), to prepare lithium salts. Suspensions of polymeric salts were prepared in insulating silicone oil, at a series of concentrations (c = 5-30 %, m/m). Sedimentation stabilities of these suspensions were determined. Flow times of the suspensions were measured under no electric field (E = 0 kV/mm), and under an applied electric field (E * 0 kV/mm) and an ER activity was observed for all the suspensions prepared. Further, the effects of concentration, shear rate, electric field strength, frequency, promoter and temperature onto ER activities of copolymeric salt suspensions were investigated. Dielectric properties of copolymeric salt were determined. Science Code :405 KeyWords :Poly(4-vinyl pyridine) / po!y(2-hydroxyethyl methacrylate), Electrorheological fluids, rheology, ionomers. Page Number :13S Adviser :Prof. Dr. Halil İbrahim ÜNAL