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. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48447.