End-capped polyethylene terephthalate having superior carbonaceous char yield

End-capping of PET with triphenyl phosphate (TPP), bisphenol A bis(diphenyl phosphate) (BDP), or resorcinol bis(diphenyl phosphate) (RDP) as phosphorous containing flame retardants was performed by using benzoyl peroxide as initiator. ³¹P NMR and FT-IR spectroscopy were used to evaluate end-capping of PET and structural changes of specimens. From thermal characteristics evaluated by differential scanning calorimetry and thermogravimetric analysis, BDP and RDP end-capped PETs show flame retarding mechanisms similar to those of blended counterparts. However, TPP end-capped PET presented superior carbonaceous char yields of up to 46. 7 %, which was attributed to the condensed-phase action of TPP anchored at the ends of PET.