Resistance to time-dependent deformation of polystyrene/carbon nanotube composites under cyclic tension

Materials subject to cyclic stress can succumb to fatigue, causing failure at stress levels much lower than those in static loading cases. Herein we discussed the viscoelastic behaviors of polystyrene/multi-walled carbon nanotube (MWCNT) composites during short-term creep and recovery under tensile cyclic loading. Both unmodified and ozone oxidized MWCNTs were applied. It was found in general that the creep strain of thermoplastics dropped with decreasing temperature and stress, and with increasing content of carbon nanotubes. Moreover, with the increased cycle number, the creep strain reduced remarkably. This trend would be even more obvious at high levels of stress and temperature. Further mechanism analysis indicated the network-like structure formed by the molecule chains and nanotubes caused the reduction of the creep strain, the increasing of recovery ratio and the restriction on the mobility of amorphous molecule chains.