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To achieve better interfacial adherence of carbon fibers to the epoxy resin, the graphene modified with ammonia and 3-Glycidyloxypropyl trimethoxysilane (GPTMS) was utilized to modify the epoxy resin. Subsequently, a simple two-step method of wet impregnation and the thermoforming process was employed to fabricate the CF/graphene-modified epoxy (CF/EG/EP) composites. The interfacial properties of CF/EP composites were studied using microdroplet debonding and short-beam shear tests on modified graphene (MEG). It is shown that the incorporation of GPTMS-modified graphene into the CF/EP composites strengthened the interfacial and bending properties of CF and matrix, resulting in a 12.5 % growth in interlaminar shear strength (ILSS) and 22.5 % growth in flexural strength of the CF/EP composites, respectively. Meanwhile, scanning electron microscope images confirmed the effectiveness of the GPTMS-modified graphene in improving the interfacial compatibility and adhesion of CF/EP composites. [Display omitted] • Carbon fiber-reinforced epoxy modified by MEG composites are fabricated by an impregnation-thermoforming process. • The ILSS and IFSS of CF/MEG/EP composites are compared. • The flexural strength and modulus of CF/EMEG/EP composites can be increased to 1665.4 MPa and 140.2 GPa, respectively. [ABSTRACT FROM AUTHOR]

The surface topography and interface characteristics play a significant role in determining the mechanical properties of carbon fiber reinforced polymer (CFRP) composites. These features are primarily influenced by the surface chemical structures and their interactions with the matrix resin. Here, we developed a rigid-flexible coating consisting of polyetheramine (PEA) and polydopamine (PDA) on the fiber surface to control the interface and improve the mechanical properties of CFRPs. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrum (FT-IR) results validated the successful introduction of polymeric chains and fiber surface characteristics including rough surfaces, slim polymer layers and uniform dots were examined by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Contact angle tests indicate that the functionalized coating noticeably enhances the interaction force between carbon fibers, promoting improved wettability by the matrix resin. The bending and interlaminar shear strength of CFRP prepared by functional carbon fiber are increased by 45.76 % and 47.63 %, respectively. The drop weight impact (DWI) test confirms the positive effect of improved interfacial properties on the out-of-plane impact resistance of CFRPs. [Display omitted] [ABSTRACT FROM AUTHOR]