The feasibility of producing MWCNT paper and strong MWCNT film from VACNT array

This study sought to produce carbon nanotube (CNT) pulp out of extremely long, vertically aligned CNT arrays as raw materials. After high-speed shearing and mixing nitric acid and sulfuric acid, which served as the treatment, the researchers produced the desired pulp, which was further transformed into CNT paper by a common filtration process. The paper’s tensile strength, Young’s modulus and electrical conductivity were 7.5 MPa, 785 MPa and 1.0×10⁴ S/m, respectively, when the temperature of the acid treatment was at 110°C. Apart from this, the researchers also improved the mechanical property of CNT paper by polymers. The CNT paper was soaked in polyethylene oxide, polyvinyl pyrrolidone, and polyvinyl alcohol (PVA) solution, eventually making the CNT/PVA film show its mechanical properties, which increased, while its electrical conductivity decreased. To diffuse the polymer into the CNT paper thoroughly, the researchers used vacuum filtration to fabricate a CNT/PVA film by penetrating PVA into the CNT paper. After a ten-hour filtration, the tensile strength and Young’s modulus of CNT/PVA film were 96.1 MPa and 6.23 GPa, respectively, which show an increase by factors of 12 and 7, respectively, although the material’s electrical conductivity was lowered to 0.16×10⁴ S/m.