Facile preparation of a hydrophobic intumescent flame retardant toward simultaneously enhanced flame retardancy and smoke suppression of thermoplastic polyurethane

In this work, a hydrophobic intumescent flame retardant (HIFR) based on ammonium polyphosphate (APP), tannic acid (TA), CuO and polydimethylsiloxane (PDMS) was fabricated via an aqueous phase reaction. The surface of the HIFR was coated with spherical CuO nanoparticles and has a water contact angle of 130.6°. In comparison with APP, the HIFR exhibits higher flame-retardant efficiency and weakens the negative impact on the mechanical properties of TPU. The introduction of the 4 wt% HIFR results in 29.4%, 9.9% and 86.3% reduction in the peak heat release rate, total heat release and total smoke production of TPU, respectively. Meanwhile, TPU/4HIFR displays an increase in the Young's modulus, tensile strength and elongation at break of 8.3%, 13.1% and 12.2%, respectively, compared with TPU/4APP. It is of great significance to fabricate polymer composites with excellent flame retardancy and respectable mechanical properties. This work proposes a feasible strategy for the design of high-performance polymers with serviceable mechanical properties and low flammability, expecting to explore a series of practical applications in industry. In this work, a hydrophobic intumescent flame retardant (HIFR) based on ammonium polyphosphate (APP), tannic acid (TA), CuO and polydimethylsiloxane (PDMS) was fabricated via an aqueous phase reaction.