Methods and systems for making carbon fibers for high temperature applications

The present invention relates to a method for the continuous production of low thermal conductivity endless filament yarns with a compact, homogeneous structural morphology. The presently disclosed methods utilize safe and recyclable ionic liquids (IL) to produce carbon fiber precursors from cellulose. The fibers are produced by the carbonization of cellulose carbon fiber precursors. The precursor fiber filaments have an increased tear resistance with simultaneously sufficient elongation, a round or crenulated cross-section, and homogeneous fiber morphology. The filament yarns exhibit performance characteristics similar to those produced from traditional viscous rayon. The resulting fibers are especially suited for aerospace applications in composite materials used at the limits of high temperatures, for instance in structures found in rocket nozzles or atmospheric reentry heat shields on spacecraft.