Structure transformation and interfacial properties enhancement of high-strength carbon fibers (T800) grafted by glycidyl methacrylate via heat treatment synergized with ionizing radiation

Background: Functionalization of T800 carbon fiber (TCF) with high carbon content and strong surface inertness is a huge challenge, which limits the preparation and application of high-quality carbon fiber reinforced polymer. Methods: To solve the problem, the high-strength TCF grafting by glycidyl methacrylate (GMA) via heat treatment synergized with ionizing radiation was performed using different methods. Significant Findings: The novel characteristic peaks at 1730 cm−1 and 1250 cm−1 indicate that GMA has been grafted onto the TCF surface with a calculated grafting rate of 12.4 %. The oxygen content on the TCF surface significantly increased from 5.65 % to 22.86 %. It was found that the radius of gyration (Rg) of the internal micropores of TCF decreased from 5.09 nm to 4.28 nm after grafting by X-ray small angle scattering, a reduction of 15.9 %. After graft modification, the water contact angle of TCF was reduced from 125° to 103° The -COOH introduced by heat treatment should be the main reason owing to the successful grafting of GMA onto TCF. After irradiation grafting, the interfacial shear strength of TCF and epoxy resin increased from 50.84 MPa to 59.34 MPa, an increase of 16.72 %. The present work demonstrates that heat treatment co-irradiation grafting is an effective method for TCF modification, which promotes the preparation and application of high-performance CF/epoxy composites.