The manufacture of high mechanical strength cellulose‐based carbon fibers (CFs) is accomplished in a continuous process at comparably low temperatures and with high carbon yields. Applying a sulfur‐based carbonization agent, i.e., ammonium tosylate (ATS), carbon yields of 37% (83% of theory), and maximum tensile strengths and Young's moduli up to 2.0 and 84 GPa are obtained already at 1400 °C. For comparison, the use of the well‐known carbonization aid ammonium dihydrogenphosphate ((NH4)H2PO4), ADHP, is also investigated. Both the precursor and the CFs are characterized via elemental analysis, wide‐angle X‐ray scattering, Raman spectroscopy, scanning electron microscopy, and tensile testing. Thermogravimetric analysis coupled with mass spectrometry/infrared spectroscopy discloses differences in structure formation between ATS and ADHP‐derived CFs during pyrolysis.

Reversible-addition fragmentation-transfer (RAFT) polymerization of acrylonitrile (AN) was performed with 2-(2cyano-2-propyl-dodecyl)trithiocarbonate as RAFT agent and azobis(isobutyronitrile) as initiator. Linear polyacrylonitrile (M n 5 133,000 g/mol, PDI 5 1.34) was prepared within 7 h in 86% isolated yield. High-yield copolymerization with methyl methacrylate (MMA) was performed and copolymerization parameters were determined according to Kelen and T€ ud€ os at 90 C in ethylene carbonate yielding r AN 5 0.2 and r MMA 5 0.42. The molecular weights, polydispersity indices (PDIs), and MMA content of the copolymer were adjusted in a way that precursor fibers could be prepared via wet spinning. These precursor fibers had round cross-sections and a dense morphology, showing tenacities of 40-50 cN/tex and elastic moduli of 900-1000 cN/tex at a fineness of 1 dtex and an elongation of 13-17%. Precursor fibers were oxidatively stabilized and then carbonized at different temperatures. A maximum tensile strength of 2.5 GPa was reached at 1350 C. Thermal analysis, infrared and Raman spectroscopy, wide-angle X-ray scattering, scanning electron microscopy, and tensile testing were used to characterize the resulting carbon fibers.

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We report on a new process for the spinning of high-performance cellulosic fibers. For the first time, cellulose has been dissolved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium octanoate ([C2C1im][Oc]) via a thin film evaporator in a continuous process. Compared to other ILs, [C2C1im][Oc] shows no signs of hydrolysis with water. For dope preparation the degree of polymerization of the pulp was adjusted by electron beam irradiation and determined by viscosimetry. In addition, the quality of the pulp was evaluated by means of alkali resistance. Endless filament fibers have been spun using dry-jet wet spinning and an extruder instead of a spinning pump, which significantly increases productivity. By this approach, more than 1000 m of continuous multifilament fibers have been spun. The novel approach allows for preparing cellulose fibers with high Young's modulus (33 GPa) and unprecedented high tensile strengths up to 45 cN/tex. The high performance of the obtained fibers provides a promising outlook for their application as replacement material for rayon-based tire cord fibers.

We describe the wet and dry-wet spinning of multifilament cellulosic composite fibers, namely chitin/cellulose fibers. The direct solution process for the two biopolymers based on an ionic liquid as solvent represents an environmentally friendly and alternative technology to the industrially applied viscose and lyocell process. Both cellulose and chitin possess good solubility in 1-ethyl-3-methylimidazolium propionate ([C 2 C 1 Im][OPr]) and were spun into multifilament composite fibers. Moreover, for the first time, pure chitin multifilament fibers were obtained by dry-wet spinning. The effect of chitin addition on the filament properties was investigated and evaluated by microscopic, spectroscopic, and mechanical analyses.