Accelerated degradation of Polyetheretherketone (PEEK) composite materials for recycling applications

The decomposition of Polyetheretherketone (PEEK) is carried out at 623 K within 30 min using a co-solvent system comprising of ethanol and water. It has not previously been possible to carryout the decomposition of PEEK below 703 K in aqueous media. Decomposition is achieved using catalytic quantities of caesium carbonate (Cs2CO3), as low as 19 μmol ml−1, in a high pressure bomb reactor. Carbon fibres are separated from a PEEK/carbon fibre composite and analysed by SEM-EDX. A reaction scheme is proposed for the decomposition process, producing phenol and dibenzofuran as major products. Phenol is analysed quantitatively by means of HPLC, the identification of decomposition products is performed by GC-MS. Decomposition of PEEK at 7 K above its melt temperature using Generally Recognised as Safe (GRAS) solvents represents a significant advance in the recycling of end-of-life, contaminated and deteriorated thermoplastic composite materials.