The thermal degradation of phosphorus-containing copolyesters

Two series of phosphorus-containing copolyesters were synthesized by polycondensation of phosphorus-containing monomers: poly(ethylene terephthalate)-co-poly(ethylene phenylphosphonate)s [PET-co-PEPPs] and poly(ethylene terephathalate)-co-poly(ethylene DDP)s [PET-co-PEDDPs]. Both series are considered as flame retardants in polyester fibers and polyester plastics. The phosphorus-containing polymers were characterized by NMR, IR, TGA and acid titration. Experimental results indicated that for the PET-co-PEPP higher phosphorus content results in lower thermal stability. However, an insignificant effect on thermal stability was observed in the case of PET-co-PEDDPs. Thus, the incorporation of the phosphorus linkage into the main chain results in less thermal stability than that having the phosphorus linkage as a pendant group, i.e. PET-co-PEDDPs are more stable than PET-co-PEPPs. (C) 1996 Elsevier Science Limited