Synthesis,Characterization and Properties of Novel Copolyester Containing Phosphorus Linked Pendant Groups

Novel phosphorus-containing copolyesters(FR-PET),derived from terephthalic acid,ethylene glycol and 9,10-dihydro-9-oxa-10-[2,3-di(2-hydroxyethoxy)carbonylpropyl]-10-phosphaphcnantbrene-10-oxid were synthesized by melt polycondensation.Thermal stability and flame retardant mechanism of FR-PET were investigated by simultaneous TGA/DTA and XPS.The results show phosphorus-containing copolyester exhibits better flame retardancy and anti-dripping behaviour.LOI value of the copolyester is 31.5% with a phosphorus content of as low as 0.35%.No fume or toxic gas emission is observed.DSC results show that the copolyesters have lower T_g and T_m than the neat PET,and the lower T_m is helpful to improve processing performance of materials.TGA and XPS data indicate that the copolyester exhibits the less thermal stability than neat PET due to P—O and P—C bonds cleavage in the pendent group during heating.Evidence is found indicating that phosphorus-containing pendant groups in the copolyester works in the gas phase.In addition,the phosphorus-containing copolyester fibre has good dyeing property.