Representative stress–strain curves for the nanocomposites are depicted in Fig. 1. The ultimate tensile properties reflect the expected tendency considering the presence of the nanophased fillers in the natural rubber matrix. Incorporation of nanotubes in rubber leads to an increase in tensile strength and a reduction in elongation at break as shown in Fig. 1. In this plot, nanocomposite specimens display a reduction in strain-to-failure of more than 20%. This behavior is consistent with typical particle filled-rubber samples. However, it is interesting to note that the tensile strength of the SiC/NR appears to be superior to the SWNT/NR with the same filler content, and that of the pristine natural rubber.