Mechanical performance of sustainable composite material: Wet-laid and dry-laid nonwoven textiles made out of recycled carbon fibers with thermoset and thermoplastic matrices

The utilization of recycled carbon fibers (rCF) in thermoplastic and thermoset composites shows significant potential in terms of economic and ecological benefits. rCFs offer a cost-effective alternative to virgin fibers with savings in energy and resources, contributing to a better ecological performance of the material. Currently, there is limited knowledge on the mechanical performance of non-wovens out of rCF. Therefore, this study uses production waste of virgin carbon textiles to investigate the mechanical properties of rCF composite materials utilizing two distinct nonwoven manufacturing techniques (dry-laid and wet-laid). The textiles are each combined with two different polymers: a thermoplastic PA66/6I and a thermosetting polymer based on an epoxy resin. Following this, three different characterization tests, following ASTM standards, analysing different mechanical properties are carried out: tensile, flexural, and compressive. Optical analysis was conducted to assess the impregnation quality of the fibers and the matrix as well as a fiber volume determination through wetchemical analysis. Mechanical tests show that dry-laid-nonwovens have high, repeatable stiffness (18-28 GPa) across all stress modes and superior cross-direction performance due to carding, while wet-laid-nonwovens offer uniform stiffness (16-26 GPa) with more isotropic behavior.