Currently, most of the carbon fibers are made from unsustainable fossil fuel-based precursors including high purity polyacrylonitrile (PAN) and pitch. High purity PAN is not only more expensive than wool fiber but also a limited quantity is produced because of global shortage of its monomer. In this work, various cross-linking pathways are explored as a means of altering the yield and tensile properties of carbon fiber derived from the carbonization of cross-linked wool fiber at 800°C under nitrogen. A range of ionic and covalent-bond-forming cross-linking agents including bifunctional carboxylic acids (succinic acid and sebacic acid), a disulfonic acid (naphthalene disulfonic acid), a dialdehyde (glyoxal), and dianhydrides (succinic anhydride and itaconic anhydride) was investigated. The resulting carbon fibers were characterized in terms of chemical composition, carbon yield, surface topology, crystal structure, hydrophilicity, and tensile properties. It was found that the carbon yield can be increased by 55% by using cross-linking treatments. Carbon fiber produced from untreated and crosslinked wool fibers all exhibited superhydrophilicity. Although the tensile strength of the resulting carbon fiber was relatively low in this preliminary study, the resulting fiber could have applications in the manufacturing of thermoplastic composite materials as low modulus filler.

In this work, the feasibility of using wool fibre as a carbon fibre precursor was explored as well as whether chemical treatments to wool fibre can increase the carbon fibre yield and properties of the produced carbon fibres. Wool fibres were treated with a range of chemicals including lignin, tannic acid, polystyrene sulphonate, and chlorine in conjunction with a polyamide resin. The treated fibres were stabilised in air at 160 C followed by pyrolysis at 800 C under a nitrogen atmosphere. The resulting carbon fibres were characterised in terms of carbon yield, tensile strength, surface roughness, porosity, crystal structure and surface hydrophobicity. The carbon fibre yield was 16.7% for the untreated while the lignin pre-treatment increased the carbon yield up to 25.8%. Generally the surface of the carbon fibre made from both untreated and treated fibre exhibited high hydrophilicity except the lignin and chlorine/polyamide resintreated fibre which showed hydrophobicity. Although the tensile strength achieved for the various produced carbon fibre was poor compared to a commercially available pitch-based carbon fibre, the developed carbon fibre still can be utilised in thermoplastic composite manufacturing.