Preparation of MUF/α-ZrP@MnHP@APP composite nanolayered flame retardant coating for application on expanded polystyrene (EPS) foam

Abstract

To enhance the flame retardancy of expandable polystyrene (EPS) foam, this study employed nano‑zirconium phosphate (α-ZrP), sodium phenylphosphinate (PPNa), manganese nitrate tetrahydrate (Mn(NO3)2·4H2O), ammonium polyphosphate (APP), and melamine-modified urea-formaldehyde resin (MUF) as raw materials. By constructing an integrated MUF/α-ZrP@MnHP@APP composite flame-retardant coating on the surface of EPS foam, the flame retardancy of EPS foam was effectively enhanced. Results showed that the EPS/MUF/α-ZrP@MnHP@15APP composite achieved a UL94 vertical burning classification of V-0 and a horizontal burning classification of HB. Specifically, it exhibited a limited oxygen index (LOI) of 57.8 %, a flame growth index (FGI) of 0.22, and a fire performance index (FPI) of 0.33. Compared with pristine EPS, the total heat release (THR) of this composite decreased by 51.50 %, the total smoke production (TSP) decreased by 57.61 %, and the char residue ratio increased from 0.14 % to 29.15 %. Meanwhile, the coating demonstrates excellent mechanical properties, interfacial adhesion, and optical transparency, which effectively balances flame-retardant functionality with the inherent service performance of the base material. This provides an effective strategy for the safe and eco-friendly application of EPS-based thermal insulation materials, and offers significant practical application value along with promising promotion prospects.