Cellulose‐Derived Carbon Fibers Produced via a Continuous Carbonization Process: Investigating Precursor Choice and Carbonization Conditions

Abstract

Here, the carbonization of two Lyocell type regenerated cellulose fibres is reported. Commercially available Lyocell as well as the experimental Lyocell type fibre known as Ioncell‐F spun from the ionic liquid 1,5‐diazabicyclo[4.3.0]non‐5‐ene‐1‐ium acetate ([DBNH]OAc) is investigated, which supports higher draw ratio and thus improves precursor mechanical properties. Lyocell fibres are known to have improved mechanical properties over other regenerated cellulose fibres and are therefore considered to be better carbon fibre precursor candidates. The Lyocell fibres used in this study are carbonized utilizing a scaled down identical replica of an in use carbon fibre line. The importance of this is the ability to assess the performance of the Lyocell fibres under more realistic continuous carbonization processing conditions. The tensile properties, morphology, and chemical composition of all fibres are determined. It is shown that by changing the carbonization temperature and atmosphere fibres with different mechanical properties and diameter can be produced. Elemental analysis confirms that each fibre has a carbon content of ≥90%.

Cellulose‐Derived Carbon Fibers with Improved Carbon Yield and Mechanical Properties

“…An overview of cellulose‐based CFs is given in Frank et al The mechanical properties of cellulose‐derived CFs strongly depend on the precursor type and processing conditions. Typical values for tensile strengths range from 0.5 to 1.5 GPa while Young's moduli up to 100 GPa have been reported for cellulose‐derived CFs manufactured at temperatures >2000 °C . Recently, Lewandowska et al reported on CFs prepared from rayon tire cord at 2000 °C having a tensile strength of 1.5 GPa and a Young's modulus of 71 GPa .…”

Fabrication and Specific Functionalisation of Carbon Fibers for Advanced Flexible Biosensors

“…The main purpose of the carbonization process is to remove most of the oxygen, nitrogen, hydrogen and other elements in precursor fibers by thermal decomposition in order to increase the carbon content (reach at least 90%) and make the coupling reaction between adjacent carbon chains to occur. The whole carbonization process can be summarized into three parts: pre-oxidation, low-temperature carbonization, and high-temperature carbonization (Karacan and Erzurumluoglu, 2015 ; Byrne et al, 2016 ; Hameed et al, 2016 ). The pre-oxidation takes place in an oxygen environment to modify more oxygen-containing functional groups on the surface of precursor fibers and the temperature is controlled within the range of 200–300°C by utilizing oven or muffle furnace as the heating equipment.…”

Processing of Cellulose Using Ionic Liquids

“…Despite major research activity on cellulosic precursors in the 1950–1970s, research in this field was abandoned due to disadvantages such as high production costs at low yields and the much more promising results with polyacrylonitrile (PAN)‐based precursors. However, today's interest in cellulosic CF precursors has arisen again . Unfortunately, due to impurities with lignin and hemicellulose, the porous structure, as well as the low degree of orientation, naturally grown cellulose fibers are not suitable for the production of CFs .…”