Improvements of strength and toughness of carbon nanotube/epoxy resin composites via microstructural and curing regulation

Carbon nanotubes (CNTs) fabricated via the floating catalytic chemical vapor deposition (FCCVD) method were continuously wound with ultrasonically sprayed epoxy resin (EP) to fabricate high-performance CNT/EP composite films. Dual-path structural optimization was realized through microstructural and curing control. For microstructural manipulation, ultrasonic spraying was adopted to achieve uniform CNT dispersion within the resin matrix, while pre-stretching post-treatment was applied to induce directional CNT alignment and construct a continuous reinforcing framework. From the perspective of curing regulation, flexible polyetheramine was used to replace conventional rigid curing agents (e.g., 4,4′-diaminodiphenyl sulfone, DDS), constructing a flexible cross-linked network that facilitates efficient interfacial stress transfer across the EP matrix. The optimized composite delivered an ultrahigh tensile strength of 2.48 GPa and a fracture elongation of 5.5%, yielding a tensile toughness of 75.16 J·cm −3 . Notably, this toughness value represents a 167% enhancement relative to the counterpart composite cured with rigid DDS, and outperforms the toughness of mainstream carbon fiber-reinforced epoxy composites. Such prominent mechanical advantages originate from the synergistic implementation of precise microstructural engineering and tailored curing network design.