Intumescent flame retardant coating for polyamide 6,6 (PA 6,6) fabrics containing carbon nanotubes: Synergistic effect of filler on thermal stability and flame retardancy

Flame retardant mixtures of multi-walled carbon nanotubes (MWCNTs) and intumescent flame retardant (IFR) coatings were applied to polyamide 6,6 (PA 6,6) fabrics to explore whether MWCNTs acted as a good synergist on the thermal stability and flame resistance of the IFR system. The influence of MWCNTs on the flame retardant properties and thermal degradation of the PA 6,6 fabrics were investigated by limiting oxygen index (LOI), vertical burning test (VBT), thermogravimetric analyzer (TGA), scanning electron microscopy (SEM) and cone calorimeter test (CCT). The peak heat release rate and total heat release of the IFR-PA 6,6 fabric with three kinds of wt% MWCNTs were lower than those of the only traditional IFR-PA 6,6 fabric (reduced by 74.2-76.4% and 74.3-76.5%, respectively). As compared to the traditional IFR coating, it was found that no enhancements for thermal stability and flame retardancy in terms of the ability to retard ignition were achieved for the MWCNT/IFR coating. These results demonstrated that the introduction of MWCNTs into an IFR coating can improve the flame retardancy of PA 6,6 fabric in terms of the heat release rate from CCT analysis, but it failed other burning measurements, such as LOI and VBT.