Changing a Winning Team—Replacement of Brominated Flame Retardant and Antimony Trioxide in Acrylonitrile–Butadiene–Styrene

ABSTRACT

This study examines two comprehensive approaches to reducing the amount of antimony trioxide (ATO) in brominated flame retardant (tris(2,4,6‐tribromophenoxy)‐s‐triazine bromine) (Br) in acrylonitrile–butadiene–styrene (ABS). One approach systematically substitutes Br/ATO with magnesium hydroxide (MH), while the other substitutes ATO with calcium borate, zinc borate, zinc oxide, zinc sulfide, and zinc stannate. We investigated the pyrolysis (thermogravimetry), flammability (limiting oxygen index and UL 94 tests), smoldering (smoke density chamber), and fire behavior (cone calorimeter). The study reveals that the synergism between Br and ATO is essential and sensitive to any changes. None of the additives fully replaced the Br/ATO mixture or ATO alone while maintaining the same level of flame retardancy. Replacing the Br/ATO mixture with MH reduces smoke emission during burning but increases flammability in the ignition scenario. Zinc and calcium salts considerably lower the peak of heat release rate due to the enhanced formation of a protective char layer. The residual protective layer hinders mass and heat transfer, and prolonged residence time of the decomposition products in the pyrolytic zone results in smoke reduction. This systematic investigation illustrates the challenges of replacing Br/ATO or ATO in ABS, but it also emphasizes the relevant benefits and remarkable potential of partial replacement.