Three different phosphonium sulphonates (PhSs) were synthesised and tested as PIN FRs for polycarbonate, a performance polymer widely used in a range of engineering plastics applications. The phosphonium sulphonates were tested at 5-10% loadings in polycarbonate, with in al cases 0.1% anti-dripping agent ETFE*.
UL-94 V0 (3mm) was achieved for all three PhSs at 5% loading, with optimal increase in LOI (limiting oxygen index) at 10% loading (LOI 34 compared to 25 for non(FR polycarbonate). Investigations suggested that the PhSs acted both by char formation and by flame inhibition. The most effective of the three PhSs tested included an alkene group.
* ETFE = ethyl tetra fluoro ethylene. “Phosphonium sulfonates as flame retardants for polycarbonate”, S. Hou et al., Polymer Degradation and Stability 130 (2016) 165e172 http://dx.doi.org/10.1016/j.polymdegradstab.2016.06.004