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

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.