Preparation and properties of high strength and high moduli epoxy resin composites

For high-performance carbon fiber composites, this study offers an optimum design of epoxy resin systems with different diethyltoluene diamine (DETDA) contents (10–50 wt%) to balance mechanical performance, processability, and crosslink density. The network structure of the epoxy system is adjusted by varying the DETDA levels: lower DETDA (10 wt%, TTM-1) created a dense network with stiff benzene rings, attaining a tensile strength of 137.7 MPa and a moduli of 4.9 GPa. Additionally, low processing viscosity (500 mPa·s at 80°C) was used to provide efficient carbon fiber wetting. The TTM-1 composite, reinforced with M40J carbon fibers, demonstrated greater interfacial adhesion, producing a tensile strength of 1861.8 MPa and a moduli of 226.2 GPa, which is 20% higher than systems with higher DETDA (such as TTM-5). The work addresses the trade-off between mechanical performance and manufacturability by highlighting DETDA content as a crucial parameter to optimize matrix stiffness and fiber impregnation. This method offers a logical approach to epoxy matrix design, promoting the synergistic effects in advanced composites that are crucial for structural and aeronautical applications where high moduli, interfacial strength, and processability are all required at the same time.