Production of carbon fibres from a pyrolysed and graphitised liquid crystalline cellulose fibre precursor

Regenerated cellulose fibres, spun from a liquid crystalline precursor, were pyrolysed at temperatures in the range 400–2,500 °C. Raman spectroscopy and X-ray diffraction showed that the degree of graphitisation of the fibre increased with increasing temperature. Electron microscopy, however, suggested that the fibres have a skin–core structure. This observation was confirmed by micro-Raman analysis, whereupon the ratio of the intensities of the D and G bands shows that the skin consists of a graphitised structure, whereas the core consists of significantly less graphitised material. The contributions of the graphitised skin and the inner core to the potential mechanical properties of the fibres were also assessed by following the position of the 2D Raman band during tensile deformation of the fibre. The Raman band shift rate against strain was used to evaluate the fibre modulus, which suggested a modulus of ~140 GPa for the skin and 40 GPa for the core, respectively. If this incomplete graphitisation could be overcome, then there is potential to produce carbon fibres from these novel precursor materials.