PIN flame retardants show to be effective in PEAL, a composite material resulting from recycling of TetraPak packaging. PEAL is produced in Italy by collecting used TetraPaks with paper, processing to remove paper (which is recycled), then separation of impurities and foreign polymers to give a material which is mainly around 85% low density polyethylene (LDPE) and 15% aluminium, which can be injected, extruded or compounded. PIN FRs tested were magnesium hydroxide (MH, 50-60% loading), ammonium polyphosphate (APP, 30% loading) and APP + pentaerythritol (intumescent, 3:1 ratio, 30-40% loading). Peak heat release rate was reduced by over 60% by the PIN FRs and the 40% APP (intumescent) formulation achieved UL+4-V2 @ 2mm (neat PEAL is not classified).
“Improving Fire Performances of PEAL: More Second-Life Options for Recycled Tetra Pak®”, F. Cravero, A. Frache, Polymers 2020, 12, 2357; https://doi.org/10.3390/polym12102357