Carbon nanotube buckypaper composites with high nanotube concentration and improved alignment for structural and multifunctional applications

Preformed thin sheets of nanotube networks is an effective material platform for realizing essential high nanotube concentration (>20wt.%), good dispersion and alignment in the production of nanocomposites. In this research, we demonstrated multi-walled carbon nanotube (MWNTs) buckypaper/bismaleimide (BMI) resin composites with high nanotube concentration (~60 wt.%) and improved alignment. Thin sheets of millimeter-long MWNTs were used in this study. Mechanical stretching method was developed to substantially enhance alignment and packing density of MWNTs in the resultant composites. The tensile strength and Young's modulus of the nanocomposites reached 2,088 MPa and 169 GPa, respectively, which are record-high experimental results and comparable to the state-of-the-art unidirectional IM7 carbon fiber-reinforced composites for high-performance aerospace structural applications. The nanocomposites also demonstrated unprecedentedly high electrical conductivity of 5,500 S/cm along the alignment direction. The integration of high mechanical performance and electrical conductance has great potential for developing multifunctional composite structures. New fracture morphology and failure modes due to self-assembling and spreading of nanotube ropes were also revealed.