TG and TG-MS methods for studies of the reaction between metal oxide and brominated flame retardant in various atmospheres

TG and TG-MS measurements were used to investigate the reactivity of ZnO with HBr originating from thermal degradation of TBBPA and with SbBr3 under various atmospheres. It was found, that the HBr is an excellent brominating agent for ZnO and separates zinc as a volatile bromide (50 and 70% in He and He + 5 vol% O2, respectively) from the solid residue. In inert atmosphere the formed char plays an important role as reduction agent for remaining ZnO into metallic Zn, which vaporizes completely from the residue above 890 °C. In presence of oxygen, the char is oxidized into CO and CO2 and un-reacted ZnO remains. Bromination efficiency from thermal treatment of SbBr3 + ZnO in He is about 14% only. Such low efficiency may results from highly volatile SbBr3 sublimating from the mixture above 100 °C and its high ability to form thermally stable oxybromide compound (Sb8O11Br2). Simultaneous TG-MS measurements indicate that the presence of ZnO strongly influences the TBBPA degradation pathway and causes enhancement of char formation. Catalyzing effect of ZnO on evaporation of SbBr3 was also observed.