Crack growth resistance of natural rubber reinforced with carbon nanotubes

Carbon nanotubes (CNTs)/natural rubber (NR) composites are prepared through ultrasonically assisted latex mixing combined with a two‐roll mixing process, and their crack growth behavior is examined to evaluate their fatigue properties. CNTs/NR shows a reinforcement of crack growth resistance compared to unfilled NR. The measurements of the tearing energy and the hysteresis loss show that CNTs/NR exhibits more energy dissipation than NR. Also, strain‐induced crystallization (SIC) around the crack tip of CNTs/NR and NR composite was examined at different fatigue strains. CNTs positioned at the crack tip led to a crack branching at low fatigue strain, which is responsible for the improvement of the crack growth resistance of CNTs/NR. However, the inclusion of CNTs renders NR higher crystallinity and larger crystallization zones in front of the crack tip at high fatigue strains, which allows more energy dissipation during crack growth. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48447.