Deoxyribonucleic acid‐carbon nanotubes self‐assembled interface for improved performance of milled carbon fiber reinforced epoxy resin composites

Abstract In order to improve the interfacial properties between carbon fibers and epoxy resin matrix, this paper proposes a method to prepare reinforced epoxy resin composites based on Deoxyribonucleic acid‐Carbon nanotubes (DNA‐CNTs) self‐assembled milled Carbon Fibers (mCF). DNA was used to assist the functionalization of CNTs, and the CNTs were uniformly dispersed and covered the surface of carbon fibers by self‐assembly to improve the interfacial bonding between the mCF and epoxy resin matrix. Analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), it was found that a layer of CNTs with a thickness of 100–350 nm was formed on the surface of mCF, and the distribution and thickness of CNTs varied with reaction time. The experimental results showed that the tensile and compressive yield strengths of the mCF‐CNTs/EP composites were increased by 56.36% (69.97 MPa) and 18.62% (91.32 MPa) compared to those of the pure EP, respectively. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) tests showed that the onset thermal decomposition temperature of the mCF‐CNTs/EP composites was increased to 277.28°C with an energy storage modulus of 6270.18 MPa, which was 48.75% higher than that of pure EP. The lap shear test showed that the mCF‐CNTs/EP composites not only improved the load‐bearing capacity but also exhibited greater displacement under the ultimate load, prolonged the crack extension path, and enhanced the energy absorption capacity. It is shown that mCF‐CNTs/EP composites have significant advantages in improving mechanical properties, thermal stability, and energy absorption, and have a wide range of potential applications. Highlights Optimal DNA‐CNTs time enhances CNT distribution and bonding. Self‐assembly boosts tensile and compressive strength, peaking at 7% mCF and 25–40 min. Improved thermal stability is seen with higher T 5% , storage modulus, and T g . mCF‐CNTs/EP shows better bond strength, energy absorption, and crack resistance.