Interlayer-toughening carbon fiber/epoxy composites with short ramie fiber

The interlayer-toughed carbon fiber/epoxy resin (CF/EP) composite laminates with short ramie fiber (SRF) were made through hot press laminated molding process. The interlaminar fracture toughness, the flexsural properties and tensile properties of the CF/EP composites with different SRF lengths, surface densities and surface coupling treatment were investigated. The results indicate that the insert of SRF significantly improves the CF/EP composites' mode I and mode Ⅱ interlaminar fracture toughness (G_IC and G_ⅡC), and the best interlaminar fracture toughness property can be obtained when the length of SRF is 6 mm and the surface density of SRF is 12 g·m^-2. G_IC of the composites improves from 497.48 J·m^-2 to 667.54 J·m^-2, which increases by 34.24%, and G_ⅡC of the composites improves from 508.52 J·m^-2 to 862.11 J·m^-2, which increases by 69.54%. In addition, the flexural pro-perties and tensile properties of the composites are also slighted improved with SRF. Through the observation of scanning electron microscope (SEM), it can be obtained that the toughening mechanism is related to SRF' bridging and pulling out and splitting in the process of crack propagation.