Preparation of Zeolitic Imidazolate Frameworks and Their Application as Flame Retardant and Smoke Suppression Agent for Rigid Polyurethane Foams

Abstract

In order to reduce the fire risk of rigid polyurethane foams (RPUF), three kinds of zeolitic imidazolate frameworks (ZIFs) were prepared. The results of Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM and X-ray diffraction (XRD) showed that ZIFs were successfully prepared. The combustion test results showed that the heat and smoke production of the composite containing ZIFs was obviously reduced. In particular, the peak heat release rate (PHRR) of ZIF-8/RPUF decreased from 740.85 kW/m2 (Ref. RPUF) to 489.56 kW/m2, while the PHRR of ZIF-7/RPUF and ZIF-11/RPUF is 598.39 and 583.36 kW/m2, respectively. The addition of ZIFs improved the thermostability of the composite. The T50% of ZIF-8/RPUF, ZIF-7/RPUF and ZIF-11/RPUF increased to 364, 382 and 380 °C, respectively. The maximum light absorption of ZIF-7/RPUF and ZIF-11/RPUF was about 88%, which is higher than that of ZIF-8/RPUF (75%). The results of Raman spectroscopy showed that the ID/IG value of Ref. RPUF is 2.96, while the ID/IG value of ZIFs/RPUF reduces to less than 2.80. The main mechanism of ZIFs for reducing the fire risk of RPUF was the catalysis and incarbonization of ZIFs during combustion based on the results of thermogravimetric analysis and Raman spectroscopy of char residue.

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

“…Through the cone calorimeter test, a series of important parameters such as heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), CO production (COP), CO 2 production (CO 2 P), and flame growth index (FGI) are derived to assess the smoke suppression properties and flame retardancy of materials 26 . These parameters are used to predict the size of the fire when the material burns, the rate of fire spread and the generation of harmful smoke 17 . It can be seen from the data in Table 1 that the FGI of different composite materials, the higher the value is, the greater the fire risk is.…”

“…Leaf‐shaped Zinc‐Cobalt hybrid zeolite imidazole frameworks‐L (Zn&Co‐ZIF‐L) is a zeolite imidazole skeleton material with microporous structure synthesized by using Zn 2+ , Co 2+ and 2‐methylimidazole based on a certain ratio. These three zeolitic imidazolate frameworks‐L (ZIF‐L) have flame‐retardant elements and nitrogen elements, their lamellar structure may play a barrier role in the combustion process, and their decomposition products have a catalytic carbon‐forming effect 17 …”

Comparative Study on the Flame Retardancy and Retarding Mechanism of Rare Earth (La, Ce, and Y)-Based Organic Frameworks on Epoxy Resin

“…Moreover, the nanoscale metal ions/clusters in MOFs play an important role in improving the FR and smoke suppression performances. Up to now, several metal centers have been selected to research the MOF-derived FRs, such as Co, 7 − 9 Zn, 10 − 12 Zr, 13 − 15 Al, 16 , 17 Fe, 18 − 20 Cu, 21 , 22 Ni, 23 − 25 Sn, 26 and Mo. 27 Hu et al have found that 2D layered and 3D block MOFs combining common transition metals (such as Fe, Co, Zr, and Ni) and rigid organic complexes showed better flame retardancy with less dosage.…”

Effects of hexaphenoxycyclotriphosphazene and glass fiber on flame‐retardant and mechanical properties of the rigid polyurethane foam

“…The results showed that ADP significantly enhanced flame retardancy of RPUF/ADP composites, RPUF/ADP30 passed UL‐94V‐1 rating with limiting oxygen index (LOI) of 23.0 vol%. Cheng and et al [ 9 ] used three kinds of zeolitic imidazolate frameworks (ZIFs) to reduce the fire risk of RPUF. The combustion test results showed that the heat and smoke production of the composite containing ZIFs was obviously reduced.…”