Highly efficient intumescent flame retardant of dopamine-modified ammonium polyphosphate for the thermoplastic polyurethane elastomer

With the widely application of thermoplastic polyurethane elastomer (TPU), the fire safety of the TPU composites has attracted more and more attention. In this work, a highly efficient and green flame retardant (DA-APP) was synthesized via the ion exchange reaction between biologically relevant molecule dopamine (DA) and ammonium polyphosphate (APP). When the incorporation amount of DA-APP was 5 wt%, it was found that TPU/DA-APP 5 passed the V-0 rating and the LOI reached to 25.9%. Meanwhile, the peak heat release rate (PHRR) of TPU composite decreased by 732.5 kW m −2 and total heat release decreased by 19.7 MJ m −2 and total smoke release decreased by 33.6 m 2 compared to that of the neat TPU. Moreover, the flame-retarding mechanism of TPU/DA-APP 5 was analyzed by TG-FTIR and Raman characterization. The results showed that DA-APP produced amino compounds and phosphoric acid at low temperature, promoted TPU to produce water and carbon dioxide, and diluted oxygen concentration during combustion. In addition, the dense carbon layer formed on the surface of TPU played an important role to isolate the diffusion of heat and oxygen .