CHEMI-LUMINESCENCE STUDIES OF THE THERMOOXIDATION OF PEEK

A highly sensitive microcomputer-controlled chemiluminescence apparatus capable of spectral resolution of emitted light has been used to study the oxidation of thermoplastic matrix material poly(ether ether ketone), PEEK, at 110 degree C in oxygen. Even after prolonged exposure and extensive decay in the chemiluminescence signal, the samples show no change in properties or accumulation of oxidation products. Evidence suggests that after oxygen-assisted initiation, reaction proceeds by radical transfer primarily of polymer phenoxy radicals in a type of radical aromatic substitution reaction on PEEK. Similar substitution-type biomolecular termination of polymer phenoxy radicals can lead to excited polymer and benzoquinone, emitters that account for much of the oxyluminescence spectrum of PEEK. Under the experimental conditions, the benzoquinone is volatile and the product polymer should be indistinguishable from starting polymer.