Abstract. Acrylonitrile-butadiene rubber (NBR) and blends of poly(3-thiopheneacetic acid)/ acrylonitrile-butadiene rubber, P3TAA/NBR, were fabricated, and the electrorheological properties, dielectric, and electrical conductivities were investigated . The electrorheological properties were determined under an oscillatory shear mode in a frequency range of 0.1 to 100 rad/s at various electric field strengths, from 0 to 2 kV/mm, at a fixed 27°C to observe the effects of acrylonitrile content (ACN) in the rubber systems and the conductive particle concentration in the blends. For the pure rubber systems, the storage modulus response (ΔG′) is linearly dependent on its dielectric constant (ε′), and increases with the ACN content. For the NBR/P3TAA blends, the storage modulus response varies nonlinearly with the dielectric constant. The bending responses of the rubbers and the blends were investigated in a vertical cantilever fixture. For the pure rubber system, the bending angle and the dielectrophoresis force vary linearly with electric field strength. For the blend system, the bending angle and the dielectrophoresis force vary nonlinearly with electric field strength.Keywords : smart polymers, electrorheological properties, dielectric properties, acrylonitrile-butadiene rubber, poly(3-thiopheneacetic acid) eXPRESS Polymer Letters Vol.2, No.12 (2008) [866][867][868][869][870][871][872][873][874][875][876][877] Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2008.101 The presence of fillers, such as electrically conductive additives, in elastomers has been observed to change their electrical, dielectric, and mechanical properties, along with their morphology [3,5,6]. The incorporation of the conductive materials into dielectric elastomers has been widely studied as both magnetorheological (MR) and electrorheological (ER) fluids. Lokander and Stenberg (2003) studied the MR properties of NBR having different acrylonitrile amount as well as blends of NBR with iron particles [7]. Dynamic mechanical properties, under the influence of an electric field, of doped poly(3-hexylthiophene), P3HT, blended with a silicone elastomer have also been investigated [8]. Shiga (1997) reported the ER effect of polymethacrylic acid cobalt(II) salt (PMACo) particles in silicone gel; increase in the elastic modulus induced by an electric field was 4 kPa, with a particle volume fraction of more than 25%. As the particles were incorporated into the rubber matrix, interaction between the particles occurred under an electric field [9]. In our previous work, various matrix systems were used to investigate the electrorheological (ER) properties, with emphasis on the effects of electric field strength, particle concentration, and operating temperature. The systems were poly(dimethyl siloxane) (PDMS) networks containing camphorsulfonic acid (CSA)-doped polyaniline (PANI) particles [10]. The ER properties of PDMS gel and PPV/PDMS blends were studied for the effect of particle electrical conductivity [11]. The ER p...

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