Effect of two-dimensional zeolitic imidazolate frameworks-L on flame retardant property of thermoplastic polyurethane elastomers

In this study, three kinds of two-dimensional nanoplates consisting of zinc zeolite imidazole frameworks-L (Zn-ZIF-L), cobalt zeolite imidazole frameworks-L (Co-ZIF-L), and Zinc-Cobalt hybrid zeolite imidazole frameworks-L (Zn&Co-ZIF-L), were prepared by a green and nonpolluting method. Each of the three nanoplates was added to thermoplastic polyurethane elastomers (TPU) at 3 wt% to investigate their performance in flame retardancy and smoke suppression of TPU. Compared with pure TPU, the limiting oxygen index values of Zn-ZIF-L/TPU, Co-ZIF-L/TPU, and Zn&Co-ZIF-L/TPU increased from 23.2% for pure TPU to 25.3, 26.0, and 25.7%, respectively; the total heat release of these three composite materials decreased by 7.8, 11.4, and 9.3%, their peak heat release rate decreased by 28.8, 42.8, and 43.8% and their peak smoke production rate reduced by 50, 45, and 51.5%, respectively. All three nanoplates showed good flame retardancy and smoke suppression properties. In addition, through thermogravimetric/Fourier transform infrared spectroscopy (TG-FTIR) analysis of the TPU composite and the X-ray diffraction analysis of residual char, the specific flame-retardant mechanisms and smoke suppression mechanisms were explored.

Automated summary

In this study, three types of two-dimensional nanoplates were prepared and added to thermoplastic polyurethane elastomers to enhance their flame retardancy and smoke suppression properties. The nanoplates significantly improved the limiting oxygen index values, reduced the total heat release, peak heat release rate, and peak smoke production rate of the composite materials, demonstrating good flame retardancy and smoke suppression effects. Through analysis, the specific flame-retardant mechanisms and smoke suppression mechanisms were explored.