Design of core-multi shell flame retardant towards fire safe thermoplastic polyurethane composites with low toxic fumes generation

Abstract

Superior flame retardancy and excellent smoke suppression are two significant issues in thermoplastics, especially for thermoplastic polyurethane (TPU) with extensive application in industrial fields. It is of great significance, but hardly achievable, to simultaneously impart these properties to TPU. Herein, we reported the titanium carbide and coupling agent functionalized the silicon-wrapped ammonium polyphosphate (NSiAPP@Ti3C2Tx) via hydrogen-bonding interaction and microencapsulation, which were then adopted to enhance the fire safety of TPU. The as-prepared TPU/9.0NSiAPP@1.0Ti3C2Tx composite showed the V-0 rating in the UL-94 testing and its LOI value was increased to 27.6%. Besides, the cone calorimetry results indicated that the peak of heat release rate, total smoke release, total carbon monoxide yield and total carbon dioxide yield of the TPU/9.0NSiAPP@1.0Ti3C2Tx were significantly decreased by 78.1%, 72.6%, 53.7% and 67.5%, respectively, as compared to those of pure TPU. The outstanding charring effect and excellent barrier function together with the prominent terminating action of the NSiAPP@Ti3C2Tx hybrid caused the remarkable enhancement of the fire resistance for TPU composites. This work offers a promising strategy for endowing TPU composite with high flame retardancy and superior smoke suppression.