Controlling of resin impregnation and interfacial adhesion in carbon fiber/polycarbonate composites by a spray-coating of polymer on carbon fibers

Abstract To improve the interfacial properties between carbon fibers (CFs) and polycarbonate (PC) resin, the PC resin was pre-coated onto the CF surfaces by a spray-coating method, and a post-heating process was applied for ensuring uniformity of the coating layer. To further investigate the interfacial interactions between the CFs and the coating layers, the physically-adsorbed PC resins were removed from some coated CFs by washing with solvent. The results showed that the CF/PC interfacial adhesion properties could be related to the coating thickness (or the resin impregnation) and fiber-matrix interactions. For a PC coating layer thinner than 0.15 μm, the PC could not be fully-impregnated into the CF bundles, thus leading to inferior CF/PC interfacial properties and mechanical properties in the final composites; while for a coating layer with thickness ranging from 0.15 to 0.32 μm, it allowed formation of well-impregnated interfaces; if coupled with a further hot-pressing for strengthening the interfacial bonding interactions, both the CF/PC interfacial shear strength and mechanical properties for the corresponding composites were significantly enhanced. The interfacial interactions and reinforcing mechanisms for the CF/PC composites were schematically proposed.