Fully aminated <i>p</i>‐polyaramid effectively strengthen and toughen <scp>B</scp>isphenol <scp>A</scp> epoxy resin and its warp‐knitted carbon fiber composites

Abstract Stemming from the cost‐effectiveness and broad applicability, many modification researches on Bisphenol A epoxy resin (DGEBA) and its carbon fiber composites have been done extensively. Here, following the concept of molecular composite, we prepared fully aminated p ‐polyaramid with reactive amino side groups by polycondensation and reduction reaction, aiming to construct a molecular distribution of the reinforcement within the resin matrix and achieve a satisfactory enhancement effect. Among them, after adding 1 wt% fully aminated p ‐polyaramid, Young's modulus and tensile toughness of the DGEBA epoxy resin (EP) increased significantly to 2.34 ± 0.03 GPa (+68.3%) and 4402 ± 213 kJ/m 3 (+30.5%), the flexural modulus and toughness reached 4.14 ± 0.04 GPa (+42.8%) and 0.44 ± 0.01 J (+83.3%). Moreover, the T g of EP was only decreased by 2.7°C. In addition, their warp‐knitted bidirectional carbon fiber composites also have enhancements in both flexural properties and interlaminar shear strength (all improved by more than 20%). What is noticeable is that the preparation and blending of fully aminated p ‐polyaramid are simpler and more effective than most other micro‐ or nanofillers, and the dispersion is more uniform. Thus, it can act as a highly effective reinforcement and strengthen the properties of DGEBA and its carbon fiber composite materials significantly. Highlights Fully aminated p ‐polyaramid is uniformly dispersed in EP by chemical bonds. DGEBA is strengthened and toughened without a significant decrease in T g . The tensile and flexural modulus of EP is increased by 68.3% and 42.8%. Fully aminated p ‐polyaramid can reinforce warp‐knitted carbon fiber composite.