Non-covalently functionalized black phosphorene to efficient flame retardant EVA with improved mechanical properties

The development of flame-retardant polymer materials play a vital role in reducing fire hazards and protecting both lives and property. Black phosphorus (BP) is an extremely promising flame retardant since its synergistic flame retardancy with different modifiers. Nevertheless, the issue of unven dispersion within the polymer matrix has severely restricted its practical applications. Herein, BP nanosheets functionalized with ionic liquid (IL-BP) were prepared and then compounding with EVA to improve the mechanical and the flame-retardant properties of EVA matrix. The results demonstrated enhanced compatibility of IL-BP nanosheets within the EVA matrix, leading to the 1.5%IL-BP/EVA composite displayed a 25% and 9.6% increase in tensile strength and elongation at break, respectively. Remarkably, the flammability test results demonstrated that the 1.5%IL-BP/EVA sample featured a significant decrease of 18.1% and 21.5% in total heat release (THR) and peak heat release rate (PHRR), respectively. Meanwhile, the composite also achieved a V-0 rating in UL-94 test and demonstrated superior resistance to melt dripping. The flame-retardant mechanisms of IL-BP/EVA composites in both gas phase and condensed phase were studied. This work provides a promising strategy to design synergetic flame retardants that simultaneously enhanced the fire safety and mechanical properties of EVA.