Synergy of PIN flame retardants in EVA
The combination of two nitrogen-inorganic PIN FRs (ATH aluminium trihydroxide and MB melamine borate) was tested in EVA (ethylene vinyl acetate). ATH was tested at 50 – 60 wt% and MB at 10 wt%. The PIN flame retardant EVA achieved UL94-V0. The combination of ATH and MB offered improved fire performance (loss cone calorimetry, limiting oxygen index) and decreased smoke opacity.
The authors conclude that the combined PIN FR system improves the protective char formed on the polymer surface in case of fire and increases thermal conductivity (so delaying ignition), in addition to the fuel dilution and water-release cooling fire inhibition properties of ATH alone. Furthermore, the emission of the toxic smoke gas hydrogen cyanide in fire scenarios was reduced.
“The combination of aluminum trihydroxide (ATH) and melamine borate (MB) as fire retardant additives for elastomeric ethylene vinyl acetate (EVA)”, C. Hoffendahl et al., Polymer Degradation and Stability 2015 http://www.sciencedirect.com/science/article/pii/S0141391015000658