High improvement of interfacial and mechanical properties in reinforced PP composite by grafting polyethyleneimine modified carboxylic multi-walled carbon nanotubes on short carbon fiber

The properties of carbon fiber reinforced polymer composites (CFRPs) will benefit greatly from improving interfacial performance. In this study, the interfacial properties of the PEI-CNT-CF/PP composite was improved by coating polyethyleneimine (PEI) modified carboxylic multi-walled carbon nanotubes (CNTs) in aqueous solution (PEI-CNT) onto the surface of the CF (PEI-CNT-CF) to form a network structure. The network formation changed the chemical characteristics and compatibility of CF surface by introducing amine (imine) groups, and could induce transcrystallization (TC) at interface of composite. These positive factors led to a 24.6% increasement in the interfacial shear strength (IFSS) of PEI-CNT-CF/PP, and further resulted in 16.2% and 5.3% improvement in tensile and flexural strength, respectively. SEM images of the fracture surface demonstrated a significant improvement in the interfacial adhesion between PEI-CNT-CF and PP resin. These results indicated that the PEI-CNT was a great choice to strengthen the interface of CF/PP system.