An effect of carbonization on the electrorheology of poly(p-phenylenediamine)

Abstract Particles of poly( p -phenylenediamine) were synthesized by the oxidation of p -phenylenediamine with ammonium peroxydisulfate at two oxidation levels. They were carbonized at 200–800 °C in inert atmosphere and subsequently tested in electrorheological (ER) suspensions. Scanning electron microscopy, Raman spectroscopy and thermogravimetric analysis were used to characterize an influence of the carbonization on the molecular structure and particles size and shape. Subsequently, ER suspensions were prepared by mixing polymer particles and silicone oil. In order to determine an effect of carbonization on the ER behaviour, a number of rheological measurements under various external electric fields were carried out. Dielectric spectroscopy was used for the evaluation of the influence of particles carbonization on the ER performance of suspensions as well. Although the particles carbonized at 600 °C exhibited nearly the same ER effect as the original particles due to significantly higher specific surface area, the efficiency of ER performance was the highest for original, i.e. non-carbonized particles. This is due to lower field-off viscosity in comparison to ER fluids based on carbonized particles.