Preparation of high-performance carbon fibres from PAN fibres modified with cobaltous chloride

Abstract

Preparations of high-performance carbon fibres have been tested and the results are reported in this article. Polyacrylonitrile (PAN) fibres modified with cobaltous chloride have increased the crystal size, the crystallinity and the orientation, and also improved the tensile strength by about 15–40% and the modulus by about 10–20% of the resulting carbon fibres, which were carbonized at 1300 °C. The oxygen content, theAI value and the density for the modified PAN fibres are smaller than those for unmodified PAN fibres. Because the formation of the ladder polymer in the modified PAN fibres is slow and gradual during the stabilization process, the resulting carbon fibres have a better modulus than carbon fibres developed from unmodified PAN fibres. The activation energy of cyclization,E a, is increased to 180.0 from 156.6 kJ mol−1 after the modification process. The modified PAN fibres do not reduce the time required for stabilization. The carbon fibres developed from the modified PAN fibres have a greater stacking size,L c, than those developed from unmodified PAN fibres. A higher stacking size, and therefore a higher number of crystalline carbon basal planes, is one of the reasons for the improved modulus of the carbon fibres.