Cellulose-lignin composite fibres as precursors for carbon fibres. Part 2 - The impact of precursor properties on carbon fibres

Carbon fibres, despite being responsible lightweight structures that improve sustainability through fuel efficiency and occupational safety, remain largely derived from fossil fuels. Alternative precursors such as cellulose and lignin (bio-derived and low cost) are rapidly gaining attention as replacements for polyacrylonitrile (PAN, an oil-based and costly precursor). This study uses a cellulose-lignin composite fibre, to elucidate the influence of precursor fabrication parameters (draw ratio and lignin content) on the efficiency of stabilisation and carbonisation, from the perspective of the chemical, morphological and mechanical changes. The degradation of cellulose chains was the primary contributor to the decrease in mechanical properties during stabilization, but is slowed by the incorporation of lignin. The skin-core phenomenon, a typical effect in PAN-based carbon fibres production, was also observed. Finally, the carbonization of incompletely stabilized fibres is shown to produce hollow carbon fibres, which have potential application in batteries or membranes.