Mesoporous Heat-Trapping and Smoke-Adsorbing Fe-MOFs Improve Fire Safety and Compression Resistance of Rigid Polyurethane Foam

The use of highly flammable materials such as foams, resins, and plastics has led to an increase in the frequency and severity of urban fires worldwide. To address this issue, this study developed a high-specific-surface-area mesoporous metal-organic framework (Fe-MOFs) with heat trapping and smoke adsorption. The Fe-MOFs, zinc tailings (ZTs), piperazine pyrophosphate (PAPP), and sodium lignosulfonate (LS) were used to modify rigid polyurethane foam (RPUF). Cone calorimeter combustion experiments showed that Fe-MOFs significantly reduced the heat release and smoke emission of RPUF through heat trapping and smoke adsorption. Compared to pure RPUF, the peak heat release rate (p-HRR) and total heat release rate (THR) of Fe-2 decreased by 64.5% and 68.6%, respectively, and the total smoke production (TSP) of Fe-5 decreased by 55.6%. Vertical combustion experiments showed that all RPUF achieved UL-94 V-0 rating. Thermogravimetric analysis, pyrolysis kinetics, and thermogravimetry-infrared indicated that Fe-MOFs protected RPUF during the main decomposition stage (301-446 °C) and enhanced its thermal stability by accelerating the decomposition of PAPP and LS. Residual carbon analysis revealed that the appropriate amount of Fe-MOFs helped form the solid, dense, continuous, and stable carbon layer. This carbon layer hindered flame and heat transfer and limited heat and smoke release. Physical property tests showed that Fe-MOFs affected the foaming process of RPUF. This led to increased density and compressive strength of RPUF. Compared to pure RPUF, the compressive strength of Fe-2 increased from 0.147 to 0.281 MPa. These results indicated that Fe-MOFs help to enhance the performance of RPUF. This study provides an efficient solution for the recovery of solid waste and the development of fire-resistant polymer composites.