Hydrothermal aging of carbon fiber reinforced epoxy composites with different interface structures

Four carbon fiber reinforced epoxy resin composites (CFRPs), CF/EP, CF-COOH-EP, CF-COOH/MXene/EP and CF-CONH-MXene-EP, were prepared and subjected to hydrothermal aging experiments at 55 degrees C. The changes in structure and mechanical property of these CFRPs, having different interface, before and after the aging were investigated to explore the influence of interface structure on hydrothermal aging of CFRPs. CF-COOH-EP has the highest moisture absorption because of a large number of hydrophilic groups in the interface. The Mxene nanosheets help reduce the moisture absorption rate and equilibrium moisture absorption of CFRPs CF-COOH/ MXene/EP and CF-CONH-MXene-EP is similar to that of CF/EP. The aging results in decreases of storage modulus and temperature at maximum tan delta, but the different interface structures show little influence on them. The inter -laminar shear strength (ILSS) presents a fast decline in the early aging and a gradual decrease at the following stage. The interface structure has an influence on the hydrothermal aging of the CFRPs and results in different ILSS changes. Among the four CFRPs, CF-COOH-EP presents the fastest hydrothermal aging corresponding the lowest ILSS retention rate and CF-CONH-MXene-EP keeps the highest ILSS after aging exhibiting the highest reliability.