In the article we investigated the effectiveness of a synergistic system designed to reduce the fire hazard of flexible polyurethane (PUR) foams. The examined system consisted of a carbon-based filler graphene (G), carbon nanotubes (CNTs), or expanded graphite (EG) combined with melamine polyphosphate (MPP). The investigated polyurethane foams (PUR) were synthesized at room temperature via a polycondensation reaction between a polyol and an isocyanate, with an OH: NCO molar ratio of 2:1. Both the carbon fillers and melamine polyphosphate were homogeneously dispersed within the polyol component. Thermogravimetric analysis (TGA), cone calorimetry, and microcalorimetry were used to evaluate the influence of the fillers on the thermal stability and flammability of the PUR foams. The toxicity of the gaseous products was assessed using a coupled TG-gas analysis system, while the optical density of the evolved gases was determined using a Smoke Density Chamber (SDC). The obtained results demonstrated that the applied synergistic carbon-phosphorus filler system significantly reduced the fire hazard of the tested PUR foams. In particular, the EG5-MPP system enabled the formation of self-extinguishing materials.

In this study, a new approach to improving the fire resistance of flexible polyurethane (PUR) foams is presented, based on the incorporation of cotton chemically modified with boron compounds into the polyurethane matrix. The developed system was additionally modified with melamine polyphosphate (MPP). The effects of the applied modifications on the morphology and chemical structure of the PUR composites were investigated using scanning electron microscopy and infrared spectroscopy. Thermal stability was evaluated by thermogravimetric analysis, whereas fire hazard was assessed using cone calorimetry and a smoke optical density chamber. The toxicometric index (WLC_50SM) was determined using a coupled TG-Omega 5 gas analyzer system. The results provide insight into the mechanism responsible for reducing flammability and limiting the emission of toxic combustion and thermal decomposition products through the modification of PUR foams with chemically modified cotton in combination with MPP. It was observed that, during the combustion of the developed PUR composites, the addition of cotton promotes the formation of a three-dimensional spatial network, which substantially limits heat release and the emission of toxic combustion products. Consequently, the composites exhibited a reduction in heat release of up to 67% in terms of HRR_MAX, together with decreased production of HCN and CO. Nevertheless, the formation of a protective carbon layer contributed to an increase in smoke optical density, which was associated with increased CO₂ emission. Overall, this work demonstrates the development of a new synergistic system capable of reducing both the flammability and toxicity of flexible PUR foams.