Thermal decomposition mechanism of F-3020, end-capped brominated epoxy flame retardant

This contribution investigates the mechanism of thermal decomposition of end-capped epoxy oligomers of tetrabromobisphenol A (TBBPA), denoted as F-3020, commonly deployed to control flammability of styrenic polymers. The aim is to assist with the development of co-pyrolysis processes for recycling plastics containing brominated flame retardants (BFR).
The experiments combine thermogravimetric analysis and differential scanning calorimetry, with attenuated total reflectance of the residue and on-line infrared analysis of pyrolysis gases and. F-3020 decomposes in three stages including, (Stage 1) volatilisation that commences at around 260 °C, followed (Stage 2) by dissociation of ether linkages, with the accompanying emission of 2,4,6-tribromophenol (from end caps) and methane and acetone (from hydroxypropanediyl linkages). Stage 2 also includes the formation of CH3Br and HBr from intramolecular reactions. The rate of pyrolysis in Stage 2 peaks at around 360 °C. Stage 3 commences at around 412 °C and releases debrominated or partly-debrominated fragments of F-3020, with declining discharge of CO2, CO and H2O, and ceased release of CH4 and CH3COCH3. The present measurements suggest that success of the co-pyrolysis process will depend on the effectiveness of inorganic adsorbers for fixing HBr and for debrominating CH3Br, bromophenols and volatilised molecules of F-3020 at temperatures as low as 260 °C.