The Role of CNTs in Promoting Hybrid Filler Networking and Synergism with Carbon Black in the Mechanical Behavior of Filled Polyisoprene

The filler networking process promoted by multiwalled CNTs is studied in neat and CB-filled poly(1,4-cis-isoprene) matrices. TEM analysis, tensile, dynamic-mechanical, and electrical measurements reveal that the CNTs form a filler network at low concentration in neat PI and a continuous hybrid filler network at a lower CNT concentration in the presence of CB, with a remarkable increase of the nonlinear dynamic-mechanical behavior of the nanocomposites at low deformation. A synergistic effect between CB and CNTs is demonstrated. The addition of CNTs to the CB-filled PI matrix leads to initial modulus values much larger than those calculated by simple addition of the two initial moduli of the composites containing only CB and only CNTs, respectively.