Continuous Plasma‐Assisted Sheet Molding Compounding Process for Enhanced Interfacial Adhesion and Mechanical Performance of Carbon Fiber/Epoxy Composites

ABSTRACT The sheet molding compound (SMC) process has attracted significant attention owing to its cost‐effectiveness and compatibility with continuous production. However, the final products obtained from the SMC process show poor mechanical performance owing to the chopped carbon fibers (CFs) and low interfacial CF‐matrix adhesion. Therefore, this study aimed to enhance the mechanical performance of the SMC composites by strengthening CF‐matrix interfacial adhesion through the introduction of atmospheric‐pressure plasma (APP) treatment into the SMC process. The surface morphology, roughness, and wettability were examined, and the mechanical performance of the fabricated SMC composites was evaluated and correlated with the plasma treatment time used for CF surface modification. For a treatment time of 3.60 s, the storage modulus of SMC composites increased by 46.6%, and tensile strength and modulus reached 213.5 MPa and 11.3 GPa, respectively, achieving increases of 97.2% and 200% from those of the control specimen. The observed enhancements are attributed to the combined effects of surface roughening and plasma‐induced chemical functionalization of the CFs. These findings demonstrate that continuous APP treatment can be effectively incorporated into the SMC process.