Fire behavior of flame-retardant polyurethane semi-rigid foam in presence of nickel (II) oxide and graphene nanoplatelets additives

Flame-retardant features are one of the most sought characters among polymer- properties as they are used in broad ranges of applications. However, understanding and optimizing the scientific technology of their design, remains the principal challenge to improve their effectiveness. Thus, herein we would put in relief the contribution of graphene nanoplatelets as flame retardant (FR) of semi-rigid nanocomposite polyurethane foams (RPUFS), combined with nickel oxide nanoparticles as toxic gas reducer. The RPUFs nanocomposites were prepared using a facile one-step method followed by their characterization using: Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffractometer (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and mechanical tensile test. The efficiency evaluation of particles addition on flammability of rigid nanocomposite foams was carried according to Limiting Oxygen Index (LOI) and vertical burning test (UL 94 V). The obtained results show that the addition of both of NiO and/or GnPs have improved the tensile behavior of foams and kept a stable bulk density, they have also shown an outstanding effect by limiting the flame propagation during the combustion process, through a creation of compact and homogenous char layer. Moreover, the TGA-FTIR analysis has put forward the pinpointed role of NiO on the highest reduction of CO gas release. The most promising results were obtained for the samples designated as RPUF6, containing 2 wt% of NiO and 1.5 wt% GnPs, for which the highest reduction of gas release was observed and better thermal and mechanical properties compared to the neat RPUF, confirming the paramount role of these additives.

Automated summary

This study highlights the contribution of graphene nanoplatelets and nickel oxide nanoparticles as additives to improve the flame-retardant and mechanical properties of polyurethane foams. The addition of these nanoparticles resulted in a compact and homogeneous char layer formation, limiting flame propagation and reducing gas release during combustion. The most promising results were observed for samples containing 2 wt% of NiO and 1.5 wt% GnPs, demonstrating their paramount role in enhancing the performance of the foams.