Thermal decomposition of flame retarded polycarbonates

The effect of tetrabromobisphenol A (TBBA), ammonium polyphosphate (APP) and tris(2,4-di-ter-dibuthylphenyl-phosphite) (TBP) flame retardants were examined on the thermal decomposition of polycarbonate by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry/mass spectrometry (TG/MS) techniques.The maximal rate of polycarbonate decomposition shifted to a slightly lower temperature in the presence of TBBA. More than 20 bromine containing products were identified among the pyrolysis products of the polycarbonate sample containing TBBA flame retardant at 550 and 700 °C temperature. Significant decrease of the total evaluated volatile compounds was found at 550 °C from the APP blended polycarbonate and at 700 °C pyrolysis temperature in the presence of both phosphor-containing flame retardants investigated. The presence of the examined phosphorous flame retardants has no effect on the temperature regarding the radical decomposition of polycarbonate, while partial hydrolysis takes place at a lower temperature due to APP. The polycarbonate chain keenly decomposes under gradual heating in the temperature range of ammonia evolution from APP. The product analysis indicates that APP accelerates the formation of phenol and isopropylene phenol from the bisphenol A segments of polycarbonate.