Effectiveness of a polymeric brominated – antimony flame retardant system (brominated polystyrene 10% + antimony trioxide 5%) BFR-ATO was compared to PIN FR systems (aluminium diethylphosphinate 15% with/without nanoclay 2.5% OMMT organically modified montmorillonite) in glass fibre reinforced PBT poly(butylene terephthalate).
The BFR-ATO system achieved the lowest heat release rate (HRR), but the PIN system reduced both HRR and mass loss, especially with nanoclay addition. Smoke emission was lowest with no flame retardant, and highest with BFR-ATO, whereas carbon monoxide emission was also lowest with no flame retardant but highest with the PIN systems. The authors consider that these differences in effects of FR systems are due to the BFR-ATO system acting mainly in the gas phase. They note that LOI and UL94 tests do not identify these differences, and also do not identify the differences in smoke emissions.
“Fire performance of brominated and halogen‐free flame retardants in glass‐fiber reinforced poly(butylene terephthalate)”, M. Suzanne et al., Fire and Materials, 2017:1-10 http://dx.doi.org/10.1002/fam.2453