Effect of graphitic additives on the rheology of cellulose solutions for the preparation of templated carbon fiber precursors

The performance of biobased carbon fiber (CF) can potentially be improved to a new level by enhancing its graphitization by including graphitic additives as structural templates in the precursor. Mixing these additives in the precursor spinning solution can influence the solution rheology and thus its spinning process and ensuing carbonization, though these effects are not well understood. Herein, we analyze the influence of carbon nanotube (CNT) and graphene oxide (GO) additives on the rheology of cellulose solutions in ionic liquid as well as the subsequent precursor and CF preparation. Addition of GO both thickened the solution and clearly increased its elastic (solid-like) nature in comparison to pure cellulose solution in ionic liquid, while CNT only made the solution moderately more elastic. Still, solutions with both additives were spinnable into continuous precursor fibers, though the inclusion of GO somewhat disturbed cellulose alignment in the fiber, as observed through X-ray diffraction. In addition, GO induced structural order development, observed as a decrease in the intensity and ratio between the Raman peaks at ~1300 cm⁻¹ (related to disorder) and ~1600 cm⁻¹ (related to sp2-hybridized carbon in general).