PIN FRs for recycled PET

Combining P and N PIN FRs for fire and mechanical performance in foamed recycled polyethylene - terephthalate (rPET). Ammonium polyphosphate (APP), aluminium diethylphosphinate and melamine polyphosphate (MPP) were tested. 20% OP achieved UL-94 V-0 (4 mm) and fire performance was further improved with 15% loading OP plus 5% MPP, self-extinguishing in around 5 seconds without dripping. The authors suggest that this is because of synergy between the charring effect of the OP PIN FR and the swelling effect of MPP. The combination of OP and MPP only slightly deteriorated mechanical properties of rPET and the authors suggest that this is a viable solution for ensuring fire-safe industrial applications of recycled PET foams.

“Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends”, V. Szabó et al., Crystals 2025, 15, 80. https://doi.org/10.3390/cryst15010080