Facile Enhancement of Mechanical Interfacial Strength of Recycled Carbon Fiber Web-Reinforced Polypropylene Composites via a Single-Step Silane Modification Process

In this study, a surface treatment process was introduced into the conventional dispersion process for preparing wet-laid nonwoven fabrics to improve their properties, using recycled carbon fibers (rCFs). The conventional binder solution was replaced with a solution containing different amounts of silane, and the changes in the fiber properties of the prepared nonwoven fabrics were examined after the addition of modified rCFs and polypropylene. FE-SEM analysis confirmed that a silane layer was formed on the rCF surface due to the formation of a siloxane network. FT-IR and XPS analyses further confirmed the presence of siloxane bonds and chemical modification of the rCF surface. When an optimal amount of silane content was used, the mechanical strength increased by 64% compared to untreated rCFs, owing to the improved molecular chain entanglement within the matrix. Our findings indicate that the simultaneous use of dispersion and a surface treatment can produce composites with excellent mechanical properties and improved processing and surface properties; thus, this method can be used to help upcycle rCFs, thereby expanding their applications.