Structural modification for carbon nanotube film and the composite film by processing optimization

As a kind of 2D macroscopic assembly of carbon nanotube (CNT), CNT film fabricated from CNT array performs outstanding properties and potential applications in many areas. For CNT film fabricated from spinnable array, the nanotube's alignment and packing density are two important factors for improving the properties. In this work, inspired by the unique transferring process, we intended to adjust the CNT stacking status in the film via optimizing the winding process and assisting appropriate post-treatment. Array-based CNT films with different winding parameters were fabricated to study the effect of winding speed and winding thickness on the film's tensile properties. It is revealed that related with the drawing force, the winding speed plays an important role in tuning CNTs arrangement in nanotube sheet. Within a certain range, increasing speed is helpful to straighten and uniformly disperse nanotubes, and further improve the tensile properties of the film. While for winding thickness, appropriate reducing thickness is favorable for sheets compaction and decreasing defects, which further enhance the properties. Additionally, combining the low elongation feature of array-based CNT film, little-ratio post-stretching is applied on the films, which is also proved to be efficient for densifying and aligning, stimulating the film stronger and more conductive simultaneously.