Electrical and Mechanical Properties of Manganese Dioxide (Magnetite) Filled NBR Rubber Blends

Different concentrations of fillers MnO2 and Fe3O4 were incorporated into acrylonitrile butadiene rubber (NBR) interlinked composites. The prepared composites systems were irradiated by electron at constant dose of 50 kGy to induce radiation crosslinking under atmospheric conditions. The effect of different contents of fillers and temperature variation on dc electrical conductivity, sigma(dc)., in NBR/MnO2 and NBR/Fe3O4 mixture system was investigated. The calculated activation energy, sigma E-dc., from dc. was found to be highly affected by both the type and concentration of the fillers. Whilst, the dielectric properties namely; dielectric constant, epsilon', dielectric loss, epsilon'', and the ac electrical conductivity, sigma(ac)., were measured as functions of frequency, temperature and for different filler concentrations of MnO2 and Fe3O4. The ac electrical conductivity was calculated from dielectric measurements and by employing a simple relationship. The analysis of the ac. results shows that the conductivity increases up to a temperature of about 330 K. Further increase of temperature reduces the conductivity of Fe3O4 samples, while, the conductivity of MnO2 samples tends to show almost constant values after this temperature. Mechanical properties, tensile strength (TS), tensile modulus at 100% elongation (M100), and hardness were established as a function of different concentrations of filler MnO2 and Fe3O4. It was found that, filler incorporation into the NBR matrix is one of the major factors that enhance the tensile strength as well as hardness resistance. While, the elongation at break shows an adverse behavior by increasing content of MnO2 and Fe3O4 filler.