Crack growth behavior of natural rubber influenced by functionalized carbon nanotubes

In this work, the silane coupling agent bis-(triethoxysilylpropyl)-tetrasulfide (TESPT) is used to modify the carbon nanotubes. After modification, carbon nanotubes can be well dispersed in the natural rubber (NR) matrix and form a strong and flexible network. Based on the original real-time crack tip morphology monitoring, crack propagation and scanning electronic microscopy tests, it is revealed that modified carbon nanotubes filled NR samples (NR/F-CNTs) have better crack resistance. It is found that modified carbon nanotubes can resist the cavitation process during cyclic loading. Crack tip morphology monitoring tests indicate that the crack tip of NR/F-CNTs is rougher and the ligaments are thinner and densely distributed. A crack branching phenomenon is also observed. It proves that F-CNTs increase the energy consumption of NR during cyclic loading. It is concluded that the F-CNTs used in this work improve the crack resistance of NR in two ways: the one is cavitation resistance and the other is the increase of energy consumption for crack propagation. (C) 2016 Wiley Periodicals, Inc.