Structure and electrical resistivity of individual carbonised natural and man-made cellulose fibres

Abstract

Carbon fibres were produced from two natural and two man-made cellulose fibres, respectively, in a high-temperature carbonisation process. The structure of the fibres was analysed by means of wide-angle X-ray scattering and Raman spectroscopy. It was found that longitudinal shrinkage of the fibres during carbonisation is correlated with the degree of orientation of cellulose crystals as determined by wide-angle X-ray scattering. Numerous micro-scale defects were found in carbonised natural cellulose fibres, particularly hemp, whereas the structural integrity of carbonised man-made cellulose was better preserved. Both Raman spectroscopy and wide-angle X-ray scattering revealed a trend of diminishing electrical resistivity with increasing structural (graphitic) order in the fibres. Overall, the electrical resistivity of cellulose-derived carbon fibres was between 40 and 70 Ω µm, which exceeds the resistivity of fossil-based carbon fibre by a factor ten.