Supercritical propanol, a possible route to composite carbon fibre recovery: A viability study

Supercritical propanol has been used to extract and remove the epoxy resin from the surface of a carbon fibre composite material. The process appeared to be effective when operating above 450 °C and above 50 bar. The recovered fibres were found to be virtually as strong, in terms of tensile strength, as the virgin fibres indicating that little had been done to damage their structural integrity. One advantage of this method is that the polymer, as well as the fibre material, can be recovered. The polymer was analysed to investigate what chemical transformations had occurred during treatment. It is seems likely that the amide cross-linker is broken in the polymer to release a residue with a relatively high molecular weight.