Study of the reactions between tetrabromobisphenol A and PbO and Fe ₂O₃ in inert and oxidizing atmospheres by various thermal methods

DSC, TG, and TG.MS techniques were used to investigate the reactivity of PbO and Fe₂O₃ with HBr from thermal degradation of tetrabromobisphenol A under inert and oxidizing atmospheres. The HBr acted as an excellent brominating agent for PbO and separated Pb as a volatile bromide (79 and 90% in He and He + 5 vol% O₂, respectively) from the solid up to 580 °C. For Fe₂O₃, the amount of vaporized bromide was only 20 and 13% under inert and oxidizing atmospheres, respectively. In inert atmosphere the formed char acted as a reducing agent for converting the remaining oxides into metallic forms. For TBBPA + PbO, about 3% of metallic Pb remained in the residue as most of the oxide vaporized below 970 °C. The unreacted Fe₂O₃ underwent progressive reduction into metallic Fe (75%), which remained in the residue. In oxidizing atmosphere, the unreacted PbO vaporized completely, while the Fe₂O₃ remained unchanged in the residue. The organic char decomposed and vaporized as carbon mono- and di-oxides. Simultaneous TG-MS measurements indicated that the presence of PbO and Fe₂O₃ strongly accelerated TBBPA degradation and enhanced char formation.