LAUSR

Abstract Dual-filler systems may promote synergetic effects to mechanical properties in rubber compounds. The use of metakaolin (M) and carbon black (C) in nitrile rubber (NBR) compounds was studied with respect to rheological and non-obvious mechanical tests. The reaction order of the curing process was not influenced by the filler system, however, carbon black presented a slowdown effect in the vulcanization process. Cyclic uniaxial tests indicated that stress softening was observed even for unfilled compound; however, notably only-carbon black filled compound experienced the highest values for decrease in stress softening after second cycle. Although the polymer chains alone are the main driving force of hysteresis, it was more negatively affected by carbon black than by metakaolin. Moreover, dual filler composites experienced balanced results for stress softening, and other properties as Payne effect and complex viscosity.