Reduced Graphene Oxide Nanosheet-Enhanced Lyocell Filaments: Structural Modifications and Preoxidation Behavior

A thorough understanding of how precursor composition affects preoxidation behavior is pivotal for developing Lyocell-based carbon fibers. The incorporation of nanofillers such as graphene holds significant promise for optimizing the properties of Lyocell fibers and their derivative carbon fibers, thereby expanding their application potential. But, so far, the underlying mechanisms through which these nanofillers mediate the preoxidation process remain largely unknown. In this work, the influence of reduced graphene oxide (rGO) nanosheets on the evolution of multiscale structures and properties of Lyocell filaments during thermal stabilization is systematically investigated. The results indicate that the incorporation of rGO nanosheets into Lyocell filaments accelerates the preoxidation process while ensuring a mild structural evolution, leading to higher preoxidation and char yields. It also promotes the dissociation in crystalline regions, increases the proportion of vinyl structures in the chemical composition of preoxidation intermediates, and reduces the degree of aromatization (upgraded oxidation level) at 240 °C, which facilitates char retention under high-temperature conditions. These effects are associated with the nanoscale features of GO nanosheets, which promote more ordered molecular arrangement and improved heat dissipation with in the fibers. This study provides a theoretical basis for enhancing the formation quality of Lyocell preoxidized fiber by the addition of carbon-based nanofillers, which are desirable for the further development of high-performance carbon fibers.