A combination of PIN flame retardants was tested in extruded polystyrene (100 x 100 x 3 mm sheets), showing to be effective in ensuring self-extinguishment (combustion stops when flame heat source is removed), preventing ignition and reducing heat release.
Peak heat release was reduced by around half, from 870 to 430 W/g. The PIN flame retardant tested was a combination of ammonium polyphosphate (APP), melamine and a carbon source (pentaerythritol), dosed at 0 – 30 % by weight in the polystyrene. Smoke hazard was also considerably reduced by the PIN FR, with carbon monoxide content cut to around 1/3 compared to unprotected polymer (from 0.14 to 0.05 %).
“Experimental study on polystyrene with intumescent flame retardants from different scale experiments”, Z. Wu et al., Fire and Materials, 2014 DOI: 10.1002/fam.2251