Composites based on carbon black reinforced NBR/EPDM rubber blends

This paper investigates the effect of carbon black filler (CB) (loading 60–100 phr) on the cure kinetics, mechanical properties, morphology and thermal stability of acrylonitrile-butadiene/ethylene-propylene-diene (NBR/EPDM) rubber blends. The determination of cure characteristics was estimated by Monsanto Oscillating Disc Rheometer R-100. Mechanical properties such as tensile strength, elongation at break, modulus at 200% and 300% elongation, hardness, have been measured at room temperature on an electric tensile testing machine (Zwick 1425) according to ASTM D 412. Morphology of the cross linked system was carried out by scanning electron microscope (SEM). The cure kinetics were determined from three temperature rheokinetic curves (T1 = 160 °C, T2 = 180 °C and T3 = 190 °C). From obtained results of NBR/EPDM/CB (80/20/70) composite, a correlation between mechanical properties and calculated activation energy of cross link (Eac) and reversion (Ear) process can be concluded. Maximum tensile strength values and synergism for this blend has been observed. The apparent activation energy values (Ea) of degradation were determined by the Kissinger method for NBR, EPDM and NBR/EPDM/CB rubber blend. Ea for the NBR/EPDM/CB rubber blend composite is lower (45.1 kJ/mol) compared to Ea for the rubber based on NBR (156 kJ/mol) and EPDM (75 kJ/mol), which indicates easier formation of rubber blend.