The ultra-low temperature resistance carbon fiber/epoxy composites and failure mechanism

Hydrogen embrittlement is a significant flaw in ultra-low temperature storage materials, leading to potential hydrogen leakage and subsequent explosions. In this study, an excellent cryogenic properties carbon fiber (T300) /epoxy composite (CFRP) is prepared by having diglycidyl 4-cyclohexene-1,2-dicarboxylate with excellent cryogenic properties as matrix material, bis(3-aminopropyl)-capped polydimethylsiloxane (M n = 1000) as a curing agent, and 2-ethyl-4-methylimidazole as an accelerator. The experimental results show that the tensile strength of the pure epoxy resin is increased to 37.97 MPa and the elongation at break is reduced to 4.71% when the mass ratio of curing agent to accelerator is 5:5 (EP55). The CFRP prepared based on EP55 has a tensile strength of 221.7 MPa and a flexural strength of 251.5 MPa at 77 K, which only reduces by 2.63% and 12.01% compared with the room temperature, respectively, proving that the excellent ultra-low temperature resistance properties. In addition, scanning electron microscopy (SEM) is utilized to investigate the failure mechanisms of CFRP based on the [0°/45°/90°/135°] layering modes. It mainly attributed to the incorporation of Si-O flexible chains, which enhance the motility of the crosslink network at 77 K, thereby improving load transfer and promoting shear band formation.