Time dependent piezoresistive behavior of polyvinylidene fluoride/carbon nanotube conductive composite

A piezoresistive nanocomposite was prepared by melt blending multiwall carbon nanotubes (MWCNT) into polyvinylidene fluoride (PVDF). Three time dependencies were examined: quasi-static, transient and cyclic fatigue. The transient response of the strain with time showed viscoelastic behavior that was modeled by the 4-element Burger model. Under quasi-static loading the resistance showed negative pressure coefficient below yield but changed to positive pressure coefficient after yield. The transient time dependence was not observed in the resistance measurements. Under cyclic load, the stress-time and resistance-time were synchronous but the resistance peak value decreased with increasing cycles, which was attributed to charge storage in the nanocomposite.