Flexible polyurethane foams (FPF) are polymer materials that have high flammability. Fyrol PNX (FPNX) and expandable graphite (EG), have been used to modify the properties of these materials. The aim of this study was to assess the possibility of improving the thermal stability and flame retardancy of FPF by the addition of FPNX and EG fillers. The prepared foams were characterised by their apparent density, hardness, flexibility, irreversible strain and linear flammability, as well as thermogravimetric analysis (TGA), dynamic mechanical analysis, Fourier transform infrared spectroscopy (FT-IR) and pyrolysis combustion flow calorimetry (PCFC) measurements. The apparent density, hardness, flexibility and irreversible strain results showed that the addition of graphite and phosphorous fillers to the FPF makes slight changes to the mechanical properties, which remain within the acceptable norms. It was also observed that reducing the amount of Fyrol PNX and replacing it with the same amount of EG allowed similar values of linear flammability to be obtained with a simultaneous increase in thermal stability, as shown in the TGA study and the PCFC test. Moreover, it was found that the modification of flexible polyurethane foam by the addition of a mixture of FPNX and EG fillers allows the best properties of this type of materials to be obtained. This result indicates that this type of modification could be an effective way to improve the thermal stability of FPF.

The aim of this work was to verify the influence of graphite and wood-based fillers on the flammability of flexible polyurethane foams (FPF). Expandable graphite (EG) and cellulose (C) fillers were added to FPFs to improve their thermal stability and reduce their flammability. Four types of foams have been compared: FPF, FPF with the addition of EG, FPF with the addition of C and FPF with the addition of both fillers. Linear flammability tests and pyrolysis combustion flow calorimetry (PCFC) were performed to assess the flammability of these materials. It was found that the addition of cellulose does not improve the fire reaction, but a combination of both the EG and C fillers mixed together was able to achieve a small reduction in flammability, as confirmed by a linear flammability test and PCFC. The best properties observed by PCFC were from FPFs with EG. Usage of cellulose filler separately is not a good method for the assessment of higher thermal stability and lower flammability of FPFs. Thermal properties were measured by thermogravimetric analysis and dynamic mechanical analysis. These results showed that especially EG addition allows to achieve a positive effect on the thermal stability of the tested materials. Mechanical and physical tests (density, hardness, flexibility and irreversible strain) showed that the presence of graphite or cellulose filler results in changes in the properties of the FPFs, but these changes are not extensive. Fourier transform infrared spectroscopy analysis showed that only small changes exist in the chemical structure with the addition of the fillers. The introduction of EG and EG?C fillers into an FPF may reduce its flammability.