| Abstract Scope |
In this study, we utilized novel hollow carbon fibers (HCFs) with a honeycomb cross-section as lightweight reinforcements for high-performance composites fabricated via direct ink writing. The printability, mechanical performance, and underlying microstructural features of an HCF-based matrix were investigated. According to rheological tests, the pre-printing characteristics of HCF-based inks are similar to those of traditional densified carbon fibers (DCFs). However, mechanical testing found that traditional DCF composites outperform HCF composites. Possible failure mechanisms were investigated using SEM. Interestingly, this analysis revealed that epoxy infiltrated the entire channel length in the hollow fibers with easy pullout of uniform epoxy strands. Although interlocking between fibers and the matrix was expected to provide mechanical improvements, weak fiber–matrix bonding in the fiber interiors resulted in decreased strength. These findings demonstrate that appropriate sizing of the surfaces within the HCFs could provide opportunities for interlocking with various matrix systems, including high-temperature resins. |