Effect of nanotube size on the mechanical properties of elastomeric composites

Using a mesoscale coarse-grained model and dissipative particle dynamics, the mechanical properties of a cross-linked elastomer filled with surface-functionalized carbon nanotubes are investigated under uniaxial stretching, depending on nanotube length, nanotube bulk density, and crosslink density. Importantly, the system is deformed at equilibrium, allowing the cross-linked chains to be fully relaxed. Our results suggest that for a composite with chemical couplings between polymer and fillers, there actually exist different regimes of elastomer reinforcement, manifesting themselves in the stress–strain response, which is found to be dramatically dependent on the nanotube length L and the characteristic network mesh size : while the effect of the filler particles is relatively small at L −1 ∼ 1, there is a sharp increase in the mechanical modulus when L −1 ≫ 1.