Tensile properties of flexible carbon nanotube film/PVA composite at various strain rates

The quasi-static tensile properties of carbon nanotube (CNT) composites have already been extensively studied, while their impact tensile properties under high rates have rarely been investigated. In this work, CNT film/PVA composites were prepared by impregnation and hot press curing, whereas CNT films were prepared by floating catalyst chemical vapor deposition (FCCVD). Instron 3365 and the miniaturized split Hopkinson tensile bar (SHTB) were used for tensile tests at various strain rates. The results show that the tensile properties of PVA-impregnated CNT film are significantly improved, and the strain rate effect is remarkable. The tensile properties are best when the mass fraction of PVA is 1.5%. At a low strain rate of 0.001 s(-1), the maximum stress and energy absorption (EA) of CNT composites are 502.5 MPa and 63.6 MJ/m(3), respectively. And at the high strain rate of 3100 s(-1), the maximum stress and EA of CNT composites are 969.0 MPa and 166.4 MJ/m(3), respectively. Scanning electron microscopy (SEM) was used to observe the failure morphologies at tensile fracture of composites under different strain rates. At low strain rate, the failure mode is the pulling fracture of tube bundles and the crushing of polymers, while at high strain rate is the folding and spring back of tube bundles, as well as the debonding of polymers.