Nanohybrid of Co3O4 Nanoparticles and Polyphosphazene-Decorated Ultra-Thin Boron Nitride Nanosheets for Simultaneous Enhancement in Fire Safety and Smoke Suppression of Thermoplastic Polyurethane

Abstract

Thermoplastic polyurethane (TPU) is widely used in daily life due to its characteristics of light weight, high impact strength, and compression resistance. However, TPU products are extremely flammable and will generate toxic fumes under fire attack, threatening human life and safety. In this article, a nanohybrid flame retardant was designed for the fire safety of TPU. Herein, Co3O4 was anchored on the surface of exfoliated ultra-thin boron nitride nanosheets (BNNO@Co3O4) via coprecipitation and subsequent calcination. Then, a polyphosphazene (PPZ) layer was coated onto BNNO@Co3O4 by high temperature polymerization to generate a nanohybrid flame retardant named BNNO@Co3O4@PPZ. The cone calorimeter results exhibited that the heat release and smoke production during TPU combustion were remarkably restrained after the incorporation of the nanohybrid flame retardant. Compared with pure TPU, the peak heat release rate (PHRR) decreased by 44.1%, the peak smoke production rate (PSPR) decreased by 51.2%, and the peak CO production rate (PCOPR) decreased by 72.5%. Based on the analysis of carbon residues after combustion, the significant improvement in fire resistance of TPU by BNNO@Co3O4@PPZ was attributed to the combination of quenching effect, catalytic carbonization effect, and barrier effect. In addition, the intrinsic mechanical properties of TPU were well maintained due to the existence of the PPZ organic layer.

Self-Assembled Serpentine Ni3Si2O5(OH)4 Hybrid Sheets with Ammonium Polyphosphate for Fire Safety Enhancement of Polylactide Composites

“…A cone calorimeter is a useful tool to evaluate the fire safety of polymers in real fire accidents [ 30 ]. The heat release rate (HRR), total heat release (THR), and char residues of PLA composites as a function of time are presented in Figure 5 , and more detailed parameters, including time to ignition (TTI), peak heat release rate (pHRR) are summarized in Table 3 .…”

Characterization and Flame-Retardant Properties of Cobalt-Coordinated Cyclic Phosphonitrile in Thermoplastic Polyurethane Composites

“…However, TPU is an extremely flammable material, The molten droplets generated during the combustion process not only spread the fire but also release a significant amount of toxic and harmful gases, such as CO, HCN, NOx, etc. This poses a serious limitation on the application of TPU [7][8][9]. Inorganic flame retardants are commonly utilized in polymer for their non-flammable nature and high specific heat capacity, but their compatibility with TPU materials is lacking, necessitating the addition of large quantities, ultimately leading to a reduction in the mechanical properties of the polymer [10,11].…”