Mechanistic studies on fire retardant action of fluorinated additives in ABS

Small amounts of polytetrafluoroethylene (PTFE) are shown to modify the combustion behaviour of Acrylonitrile–Butadiene–Styrene terpolymers (ABS) fire retarded with a bromine/antimony synergistic system. PTFE makes ignition more difficult and decreases the rate of flame propagation in the early stage of combustion. The action of PTFE is shown to occur in the condensed phase by accumulation of fluorine in the residue of combustion and by reaction of PTFE with Sb2O3 to give volatile moieties. A catalytic action of fluorinated species formed in the presence of PTFE is suggested to take place on reactions of the bromine/antimony system increasing its effectiveness. © 1997 John Wiley & Sons Ltd.