Fatigue characterization of acid-treated carbon nanotube/epoxy composites

This study investigates how the acid treatment of multi-walled carbon nanotubes affects the fatigue behavior of carbon nanotube/epoxy composites. Nanocomposites with 0.5 and 1.0wt% acid-treated carbon nanotubes display slightly and significantly stronger fatigue strength than those with equal-content as-received carbon nanotubes, respectively. However, excessive addition of carbon nanotubes fails to increase the fatigue resistance of epoxy resins, owing to carbon nanotube agglomeration. Furthermore, the fatigue strength of nanocomposites depend on the ultimate strength rather than the carbon nanotube contents or treatments. Furthermore, how carbon nanotube contents and related treatments influence the fatigue strength of the nanocomposites is elucidated by examining the fractographs of the specimens.