Tensile properties at various strain rates of flexible carbon nanotube film densified by the combination of chlorosulfuric acid and uniaxial drawing

Abstract The quasi‐static tensile properties of carbon nanotube (CNT) films have been extensively investigated, yet research on their impact tensile properties at high strain rates remains scarce. In this article, CNT films prepared by floating catalyst chemical vapor deposition (FCCVD) method were densely arranged by chlorosulfuric acid (CSA) under wet stretching. The Instron 3365 and miniaturized split Hopkinson tension bar (SHTB) were used to conduct tensile testing at different strain rates. The findings reveal that CSA wet‐stretching markedly enhances the density and orientation of CNT films, resulting in significant improvements in tensile properties with a notable strain rate effect. Specifically, when immersed for 60 s under a draft ratio of 40% and a strain rate of 1900 s⁻¹, the densified CNT films exhibit maximum stress and energy absorption values of 777.44 MPa and 54.79 MJ/m³, respectively, achieving a 637.1% and 425.7% increase compared with the original film. This research provides a convenient and feasible strategy to prepare CNT films with high energy absorption tolerance across various strain rates, thus expanding the practical application potential of CNT films. Highlights The study innovates a posttreatment way to produce superior FCCVD CNT films. CSA treatment and wet stretching enhance CNT films' mechanical properties. Dynamic fracture strength boosts over 600% and energy absorption raises over 400%. CSA can purify FCCVD‐prepared CNT films, greatly improving their properties. The Prep can be effectively integrated with the direct spinning process.