Fabrication of a high-temperature resistant and water-soluble sizing agent to significantly improve the interfacial properties of carbon fiber reinforced epoxy composites

Applying suitable sizing agents is effective in improving the interfacial performance of carbon fiber reinforced composites (CFRPs). However, the poor thermal stability of conventional epoxy-based sizing agent limits their application at elevated temperatures for preparing advanced CFRPs. The question could lead to interfacial damage of composites at high temperatures, thus deteriorating their mechanical properties. In this work, diethanolamine (DEA) was selected to modify E51 resin to obtain a high-temperature resistant sizing agent (E51@DEA). The decomposition temperature of E51@DEA was 320 °C, which was 140 °C higher than that of E51. Furthermore, the resultant composites treated by E51@DEA 2 % showed robust interfacial performance (ILSS = 74.32 MPa, IFSS = 100.70 MPa), which was both increased by about 25 % compared to unmodified samples. In addition, the modified fiber could completely retain their interfacial reinforcement after treatment at 300 °C for 4 h. The prepared composites combined excellent thermal and interfacial properties, further expanding the application range of CFRPs.