Effect of filler geometry on interfacial friction damping in polymer nanocomposites

Single-walled carbon nanotube polycarbonate and C ₆₀ polycarbonate nanocomposites were fabricated using a solution mixing method. The composite loss modulus was characterized by application of dynamic (sinusoidal) load to the nanocomposite and the pure polymer samples. For a loading of 1 weight %, the single-walled nanotube fillers generated more than a 250% increase in loss modulus compared to the baseline (pure) polycarbonate. Even though the surface area to volume ratio and surface chemistry of C ₆₀ is similar to that for nanotubes, we report no significant increase in the energy dissipation for the 1% weight C ₆₀ nanoparticle composite compared to the pure polymer. We explain these observations by comparing qualitatively, the active sliding area (considering both normal and shear stresses) for a representative volume element of the nanotube and the nanoparticle composites. These results highlight the important role played by the filler geometry in controlling energy dissipation in nanocomposite materials.