Thermoplastic polyurethane composites based on iron tailings: An effective strategy for industrial solid waste utilization

The massive production and accumulation of industrial solid waste-iron tailings not only occupy valuable land resources but also easily cause environmental pollution and personnel injury. Based on this, the thermoplastic polyurethane (TPU)/modified iron tailings (MIT) composites were prepared by surface modification of iron tailings (MIT) and adding it as flame retardant to TPU. The combustion performance and smoke toxicity of TPU/MIT composites were analyzed by thermogravimetric analysis (TG), thermogravimetric-spectroscopy (TG-IR) and cone calorimetry (CCT). The morphology and structure of the carbon slag of the composites were analyzed by scanning electron microscopy(SEM) and Raman spectroscopy. The results showed that the initial thermal decomposition temperature (T-5%) of TPU/MIT30 composite increased at about 7(o)C, and the residual carbon content at 700(o)C increased from 3.13 wt% to 32.17 wt%. The peak heat release rate(PHRR), total heat release(THR) and total smoke release(TSR) of TPU/MIT30 composite decreased from 800.6 kW/m(2), 83.1 MJ/m(2) and 827.6 m(2)/m(2) of pure TPU to 488.0 kW/m(2), 63.6 MJ/m(2) and 517.4 m(2)/m(2), respectively. The SEM and Raman(1) spectroscopy of char residue showed that the compactness and graphitization degree of char residue for TPU/MIT30 composite was the highest, indicating that the MIT could effectively improve the fire safety of TPU composites. This study provided some ideas for the high-value utilization of iron tailings.