Synergistic Flame Retardant Effect of Ammonium Polyphosphate and Aluminum Hydroxide on Polyurethane

The flame-retardant properties of polyurethane (PU) containing ammonium polyphosphate (APP) and aluminum hydroxide (ATH) were investigated. Moreover, the flame retardant performance was investigated through thermogravimetric analysis, limiting oxygen index (LOI), vertical combustion (UL 94), and cone calorimeter. When 15 wt% APP and 5 wt% ATH were added together, the PU/15%APP/5%ATH sample shows better thermal stability and flame-retardant properties. When 15 wt% APP and 5 wt% ATH were added together, the LOI value of the PU/15%APP/5%ATH sample was 30.5%, and UL 94 V-0 rating was attained. Compared with PU, the peak heat release rate (PHRR), total heat release (THR), and average effective heat combustion (av-EHC) of the PU/15%APP/5%ATH sample decreased by 43.1%, 21.0%, and 29.4%, respectively. In addition, the flame-retardant mechanism was investigated through cone calorimeter. The APP/ATH addition simultaneously exerted condensed phase and gas phase flame retardant effects. APP and ATH have synergistic flame retardant properties.

Automated summary

The flame-retardant properties of polyurethane containing ammonium polyphosphate and aluminum hydroxide were investigated, and it was found that the addition of these compounds improved the thermal stability and flame-retardant performance. The addition of ammonium polyphosphate and aluminum hydroxide reduced the peak heat release rate and combustion heat, and exerted both condensed phase and gas phase flame retardant effects.