News
17.01.2025

PIN FR for PET plastic recycling

Mineral PIN flame retardants zinc oxide and ATH demonstrated in solvent PET recycling to PIN FR polyurethane foam. Post consumer PET flakes [poly(ethylene terephthalate] were dissolved by microwave heating in diethylene glycol (DEG) solvent with a zinc sulphate catalyst for 1 hour 20 mins, generating an oligodiol. Nano zinc oxide was synthetised by reacting zinc nitrate with potassium hydroxide, precipitating then grinding. A polyurethane foam was produced by reacting the oligodiol with methylene diphenyl diisocyanate, with DBDL catalyst (dibutyltin dilaurate), a surfactant and water as blowing agent. The zinc oxide and commercial ATH (aluminium hydroxide) were included into the foaming process at 1 – 7% and 50 – 60% loading respectively. The zinc oxide led to a lower density foam, compensating the tendency of ATH to increase foam density. The ATH increased foam cell uniformity and mechanical properties. At 60% ATH, UL 95 (VB) rating of V-0 was achieved (self-extinguishing).

“Sustainable polyurethane nanocomposite foam from waste poly(ethylene terephthalate): preparation, thermal stability, and flame retardancy”, H. Vothi et al., Macromolecular Research (2024) 32:1227–1235, https://doi.org/10.1007/s13233-024-00304-3