Flame-retardant thermoplastic polyurethane based on reactive phosphonate polyol

Propylene oxide (PO) was used to block polycarboxyethyl phenyl ethylene phosphinate (PCEPEP) synthesized by 2-carboxyethylphenylphosphinic acid (CEPPA) and ethylene glycol (EG) to obtain a reactive phosphonate polyol. The results of chemical titration analysis and Fourier transform infrared spectrum (FT-IR) showed that the end-capping effect was best when the molar ratio of PO to acidic functional groups in PCEPEP was 6:1. Moreover, the obtained phosphorus-containing polyol was used as a reactive monomer to be introduced into thermoplastic polyurethane (TPU) to prepare flame retardant TPU. Cone calorimetry results demonstrated that TPU containing 20 wt% phosphorus-containing polyol showed a reduction of 3.8%, 72.2%, and 39.3% in the peak heat release rate, total heat release and total smoke release, and an increment of 351.9% in mass retention. The addition of phosphonate polyol enhanced the char-forming performance of TPU, which effectively prevented the transfer of combustible gas and heat, and displayed a good flame retardant effect.