Pyrolysis study of poly(trimethylene terephthalate) and its phosphorus-containing copolyesters

This paper deals with the thermal decomposition behavior of PTT and its two different phosphorus-containing copolyesters, one containing 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP) with phosphorus in the pendent group, the other containing bis-4-carboxyphenyl phenyl phosphine oxide (BCPPO) with phosphorus in the backbone. TGA-FTIR and Pyrolysis-GC/MS were used to investigate the corresponding volatile products under nitrogen atmosphere. Both PTT and its phosphorus-containing copolyesters showed one decomposition stage between 330 and 446 °C. The introduction of phosphorus decreased the onset decomposition temperature due to the comparative weak P-C bond. No obvious absorption peak of P-C bond is detected with FTIR in volatile products for its low content and weak absorption. The analysis of volatile products of TGA and Pyrolysis-GC/MS revealed that they underwent different way of thermal decomposition for the different decomposition conditions. Possible thermal decomposition schemes are proposed and mass spectra of some decomposition products are also listed.