TGA/XPS Study on the Synergy of 4A Zeolites in the Intumescent Flame Retardant Ammonium Polyphosphate/Pentaerythritol

A comparative study of the effect of 4A zeolites on intumescent flame retardancy of ammonium polyphosphate/pentaerythritol(APP/PER) systems has been conducted by X ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). Detailed analysis has been carried out through thermal mass loss, and by analyzing curves of the Si/Al ratio and binding energy versus temperature. It is seen that the intensity of the third peak in TGA was reduced evidently and the relative intensity of Cls spectra in XPS increased dramatically with the temperature. It was indicated that 4A zeolite catalyzed the esterification reaction between APP and PER at lower temperatures while the Si/Al ratio of the zeolite grew at higher temperatures leading to dynamic movement on the surface and enhancement of the acid activity, in favor of APP/PER flame retardant systems.