Study on the inter-laminar shear properties of carbon fiber reinforced epoxy composite materials with different interface structures

To explore relationship between the inter-laminar shear properties and the interfacial structure of carbon fiber (CF) reinforced epoxy resin (EP) composite materials (CFRPs), four CFRPs with different interfacial structures were prepared through introducing polar groups on the surface of the CF and then combining the modified CF with the EP, including CF/EP (where no polar group was introduced), CF-COOH-EP (where carboxyl group –COOH was chemically introduced), CF-COOH/MXene /EP (where –COOH was chemically introduced while MXene was physically introduced and the MXene was non-covalently bonded to CF and to EP), and CF-CONH-MXene-EP (where both of –COOH and MXene were chemically introduced and the MXene was covalently bonded to CF and to EP). Results of inter-laminar shear strength (ILSS) of the materials and morphology of transverse and longitudinal cross-sections of the damaged materials show that with enhancing the interfacial interaction between CF and EP, the ILSS increases and the interlayer shear failure gradually changes from a single interface debonding (for CF/EP) to a combination of interface debonding and matrix fragmentation. The interfacial structure of CF-COONH-MXene-EP with higher interfacial interaction could bear more interlayer shear forces, being beneficial for improving the service life of CFRPs.