Preparation of Carbon Nanotube/Epoxy Composite Films with Superior Tensile Strength and Toughness by Impregnation under Pressure and Wet Stretching

Carbon nanotubes (CNTs) have been considered as promising reinforcements for various composites due to their excellent mechanical properties. However, CNT/resin composites prepared so far still suffer from bad dispersion, low mass fraction, and poor alignment of CNTs and their weak bonding with the resin matrix. Herein, an effective strategy toward preparing CNT/epoxy (EP) composite films with excellent mechanical properties is reported. Benefiting from a high CNT content (60.56 wt%), excellent CNT alignment from repeated prestretching, and uniform resin distribution between CNTs from pressurized impregnation and low temperature pressing, the composite film can achieve excellent mechanical properties, including a tensile strength of 4.1 GPa, elongation at break of 3.8%, and toughness of 77.9 J cm −3 . Such a strength and toughness are superior to those for the previous CNT and carbon fiber composites published in the literature.