Resin impregnation and interface property improvement of CFRP composite via modulating wettability of carbon fibers

In this work, the effects of different fiber wettability on resin impregnation during vacuum assisted resin transfer molding (VARTM) process and subsequent interface properties were comprehensively investigated. The fabrics with different surface morphology and wettability were successfully obtained via tuning the concentration of epoxy sizing agents. Results indicate that a low void content of less than 1% is achieved with the improvement of fiber wettability. Additionally, the interlayer property of composites is significantly improved by ∼12%. It is attributed to improved impregnation and capillary number, achieved by optimizing the dual-scale flow of resin in the preform via reducing the contact angle. Achieving equilibrium of dual-scale flow is an important factor in minimizing voids within the CFRP laminate. Furthermore, the introduction of epoxy functional groups significantly enhances interfacial bonding, contributing to an increase in the interlaminar shear strength of CFRP composites. This improvement effectively improves stress concentration by dispersing crack propagation. The findings in this work provide significant information for designing CFRP composites with superior mechanical properties via adjusting fiber wettability.