A New Method of Graphene Oxide and Multi‐Walled Carbon Nanotube Grafting for Improving Mechanical Properties and Thermal Stability of Carbon Fiber‐Polylactic Acid Composites

ABSTRACT In this study, a novel method of bridging multi‐walled carbon nanotubes (MWCNTs) with graphene oxide (GO) using a silane coupling agent was proposed. The approach involved acidifying MWCNTs to generate carboxyl groups. The silane was then connected to the carboxyl groups of MWCNTs at one end and dehydrated/condensed with the hydroxyl groups of GO at the other end, forming GO‐MWCNTs hybrids. Subsequently, carbon fiber fabric laminates were prepared by combining them with pure polylactic acid (PLA), GO, MWCNTs, and their mechanical mixtures (GO/MWCNTs), respectively. FTIR and XPS analysis confirmed the success of the grafting reaction, and SEM showed that the spatial structure of the GO‐MWCNTs was more stable, which effectively inhibited the stacking of GO and the agglomeration of MWCNTs. Tensile tests and thermogravimetric analysis showed that the GO‐MWCNTs composites exhibited the most excellent tensile strength and thermal stability compared with the other groups, which proved that the modification strategy could significantly enhance the comprehensive performance of PLA‐based composites. In this study, axial and 45° bias‐extension tests of CF/PLA composites reinforced with GO‐MWCNTs (concentrations ranging from 0.2 to 1.0 wt%) were conducted. The optimal mechanical properties of the CF/PLA composites were achieved at a GO‐MWCNTs concentration of 0.2 wt%. For axial tension, the fracture strength and tensile modulus increased by 129.38% and 272.4%, respectively. Similarly, in the 45° bias‐extension tests, the strength at break and tensile modulus showed significant enhancements of 172.24% and 143.08%, respectively.