Functionalized Zr‐MOFs for Enhancing Flame Retardancy and Smoke Suppression Performance on TPU

Abstract Metal‐Organic Framework (MOF) materials can be used as flame‐retardants and smoke suppressants for polymers. As a MOF material, UIO‐66(Zr) possesses higher thermal stability and controllable pore size. In this paper, UIO‐66(Zr), NH 2 ‐UIO‐66(Zr), and SiO 2 , MWCNT, and GO functionalized NH 2 ‐UIO‐66(Zr) was fabricated to improve the flame retardant and smoke suppression performance of thermoplastic polyurethanes (TPU). The experimental results show that compared with neat TPU (LOI value 19.1 %), 2 % usage of UIO‐66(Zr) and NH 2 ‐UIO‐66(Zr) can endow TPU with 26 % LOI value and vertical combustion rating of V‐1. Moreover, SiO 2 , MWCNT, and GO functionalized NH 2 ‐UIO‐66(Zr) provide TPU with above 27.8 % LOI value and vertical combustion rating of V‐0. Meanwhile, the CCT results showed that the peak heat release rate and total heat release of TPU‐U5 (added 2 % GO‐modified NH 2 ‐UIO‐66(Zr)) are 299.52 Kw ⋅ m −2 and 68.21 MJ m −2 , much lower than that of neat TPU, which are 1180.05 Kw ⋅ m −2 and 104.87 MJ m −2 , respectively. The TGA, char residue EDS and XRD analysis show that SiO 2 , MWCNT, and GO functionalized NH 2 ‐UIO‐66(Zr) could generate zirconium metal oxide during the combustion process, which acts as a physical barrier to prevent the TPU matrix by promoting the generation of carbonization layer. The zirconium metal oxide and carbonization layer also can confine flammable gases, which can delay the ignition time and hinder the overflow of gas. In addition, NH 2 ‐UIO‐66(Zr) could generate non‐flammable N 2 diluting the concentration of flammable gases. The mechanical properties of TPU composites can maintain more than 87 % of the neat TPU after the addition of 2 % SiO 2 , MWCNT, and GO functionalized NH 2 ‐UIO‐66(Zr). These results indicate that functionalized Zr‐MOFs composites could act as excellent flame‐retardants in TPU.