Large diameter carbon fibres from mesophase pitch Original Research Article

Large diameter carbon fibres of 15–60 μm were produced from naphthalene-derived mesophase pitch. In the as-spun state, preferred orientation increases with fibre diameter, confirming a previous study. However, the sheath–core structure that develops during carbonisation of large diameter fibres results in a decrease in preferred orientation. As a consequence, the strength, modulus and electrical resistivity also decrease. The coarse optical texture of the partially relaxed core allows a higher degree of graphitisation. With extended stabilisation, the core can be eliminated and the mechanical properties improve whilst the electrical resistivity increases.