OXYLUMINESCENCE OF POLYAMIDE-12

The oxyluminescence of unstabilised samples of polyamide 12 was studied in the temperature range 80-250-degrees-C. The chemiluminescence intensity was first recorded at constant oxygen pressure and temperature. The kinetic curves reveal the existence of two kinetic stages. The first one is a burst whose intensity is linked to the radical concentration at the onset of oxygen admission. The second one corresponds to the steady-state oxidation chain process in which an autoaccelerated character attributed to branching is observed. A discontinuity is observed in Arrhenius plots of maximum intensities at the melting point, T(f). A possible explanation is that the peroxyl bimolecular terminating combination is governed by segmental motion at T < T(f) and by the radical intrinsic reactivity at T > T(f). Perturbed experiments in which oxygen is abruptly suppressed, and programmed temperature experiments in which preoxidised samples are exposed in nitrogen reveal clearly that hydroperoxide decomposition contributes to oxyluminescence.