Investigation of fire-resistance mechanisms of the ternary system (APP/MPP/TiO2) in PMMA

The thermal and fire-resistance properties of the ternary system ammonium polyphosphate/melamine polyphosphate/titanium dioxide (APP/MPP/TiO2) was studied in poly(methyl methacrylate) (PMMA). PMMA-7.5%APP/7.5%TiO2 showed an interesting thermal stability and synergy effects on the peak of heat released rate (pHRR). Mechanisms were investigated following the analysis of residues and gas phase. Residues were analyzed by Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM). Gases emitted during degradation were analyzed by Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Comparison between cone calorimetry and pyrolysis-combustion flow calorimetry (PCFC) tests was a helpful tool for determining whether fire-retardancy mainly occurred by a physical or chemical pathway and for explaining the obtained results.