IN-SITU X-RAY-ABSORPTION SPECTROSCOPY AT THE K-EDGE OF RED PHOSPHORUS IN POLYAMIDE 6,6 DURING A THERMOOXIDATIVE DEGRADATION

We present a new method for studying the influence of flame retardants as a function of time and temperature by measuring the X-ray absorption spectra of the corresponding additive. Here, red phosphorus in polyamide 6,6 was investigated at the phosphorus K-edge using synchrotron radiation. The thermo-oxidative degradation of the polymer was simulated by heating the sample up to 300-degrees-C. XANES) spectra were monitored during the degradation process at different temperatures and at a constant reaction temperature as a function of time. The degradation reaction was analyzed by comparing the XANES spectra of red phosphorus and orthophosphoric acid, and the reaction was identified as an oxidation of red phosphorus to H3PO4. The results so obtained are confirmed by the EXAFS) spectra of the additive in the polymer sample recorded before and after the thermo-oxidative degradation process, and by the EXAFS spectra of suitable reference compounds.