In situ preparation of carbon fiber fabric reinforced poly(lactic acid) composites by vacuum‐assisted resin transfer molding

Abstract Carbon fiber fabric reinforced poly(lactic acid) (CFF/PLA) composites were manufactured using both vacuum‐assisted resin transfer molding (VARTM) and compression molding (CM) methods. Of the two methods, the CFF/PLA‐VARTM composite shows superior carbon fiber infiltration and interfacial adhesion compared to the CFF/PLA‐CM composite. The improved infiltration enables the carbon fibers to induce a dense group of PLA crystal nuclei along their surface, resulting in the formation of a trans‐crystalline layer (TCL) structure where the PLA lamellae grow perpendicular to the fiber axis. As a result, the interfacial adhesion is improved, and the crystallinity of the PLA in the CFF/PLA‐VARTM composite is 4.1 times higher than that of pure PLA. However, the weak infiltration of fibers and matrix in CFF/PLA‐CM composite results in poor load‐bearing ability. Conversely, CFF/PLA‐VARTM composite presents better interlayer bonding and tight fiber‐matrix wrapping, promoting effective tensile load transfer to carbon fibers, which results in higher strength and modulus. The presence of TCL structures also plays a key role in improving mechanical properties. Overall, these findings demonstrate a promising method for producing high‐performance PLA composites.