Various combinations of fourteen different PIN flame retardants were tested for fire performance and smoke emission in ABS. Samples of ABS (acrylonitrile butadiene styrene) were injection molded with 20% total loadings of PIN FRs including aluminium diethylphosphinate (AlPi), ammonium polyphosphate (APP), melamine polyphosphate, melamine poly(zinc phosphate), melamine, nanoclays, expanded graphite, zinc borate and molybdate magnesium silicate. These PIN FRs were selected as not showing environment or health concerns as used. UL 94 V-0 (4 mm) was achieved with AlPi + APP and inclusion also of expanded graphite enabled a further reduction of peak heat release rate (pHRR) and of smoke emissions. The authors conclude that AlPi + APP (with anti-drip agent) achieves better fire performance than standard brominated flame retardant (as tested) with -40% lower pHRR. Inclusion of expanded graphite or molybdate were effective at reducing smoke emission. Impact resistance was however lower than with the brominate FR, requiring further investigation.
“Systematic evaluation of bromine-free flame-retardant systems in acrylonitrile-butadiene-styrene”, A. Bachinger et al., J Appl Polym Sci. 2022;139:e51861 https://doi.org/10.1002/app.51861