Synergy in carbon black filled natural rubber nanocomposites. Part II: Abrasion and viscoelasticity in tire like applications

Synergistic effect of carbon black (CB) in presence of nanofillers (nanoclay and nanofiber) on mechanical and dynamic mechanical properties was discussed in light of electrostatic interactions and the concomitant microstructural developments, in Part I of this series. These interactions enhanced filler dispersion and ensured efficient stress transfer from the matrix resulting in improvement in properties, undiminished even by continual increase in CB loading. In this part, the micromechanical processes that influence wear behavior have been addressed conjointly with dynamic mechanical properties. Tribological characteristics were studied by sliding rubber wheel samples against a steel blade, in a specially designed abrader, in both transient and steady state conditions. Wear loss was reduced in the dual filler nanocomposites by 33% (over the CB microcomposite) in less stringent and 75% under severe wear conditions. These CB filled nanocomposites also illustrated lowering of coefficient of friction and temperature build-up. This was attributed to efficient heat dissipation due to the formation of a unique microstructural architecture by the participating fillers and also an adhering transfer film on the abraders' counterface. From viscoelastic measurements, the CB filled nanocomposites were also found to lie in the high performance window of good wet skid and low rolling resistance.