Fire Behavior of Natural Rubber Filled with Intumescent Flame Retardant Containing Graphite

Melamine salt of pentaerythritol phosphate/graphite (MPP-G) mixture was prepared by dispersing graphite flakes in MPP during its synthesis. The chemical structure of MPP-G was characterized by proton nuclear magnetic resonance, fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope. MPP-G was blended with natural rubber (NR) at different loading levels and its effect on the thermal stability and flammability properties of NR was studied. The cone calorimeter results exhibited that the addition of MPP-G to NR decreased the peak of heat release rate, mean heat release rate, total heat release, mean mass loss rate, mean effective heat of combustion, and maximum average rate of heat emission. Moreover, fire growth rate index and fire performance index values showed that NR/MPP-G composites are safer than NR. The digital photographs of char formed after cone calorimeter test indicated the formation of a coherent char. The mechanism of flame retardation was studied based on FTIR, energy-dispersive X-ray spectrometry, and XRD analysis of char residue. J. VINYL ADDIT. TECHNOL., 2019. (c) 2019 Society of Plastics Engineers