Combustion characteristics of Pinus rigida specimens treated with mixed phosphorus–nitrogen additives

• Combustion characteristics of Pinus rigida treated with flame retardant were examined using a cone calorimeter.
• Testing parameters include time to ignition, heat released rate and total heat released rate.
• Fire performance index and fire growth index were discussed.

The combustive properties of Pinus rigida specimens treated with the mixed phosphorus (P)–nitrogen (N) additives were tested. Each P. rigida specimen was painted three times with 15 wt% mixed P–N additive solutions at room temperature. After drying the specimen treated with chemicals, the combustive properties were examined using a cone calorimeter (ISO 5660-1). The time to ignition (TTI) for the specimens treated with the mixed additives was in the range, 70–109 s. The specimens treated with the mixed P–N additives showed a lower peak heat release rate by 3.8–25.5% and lower total heat release by 6.1–22.1% than those of the samples treated with the pure P–N additives. The effective heat of combustion (EHC) for the sample treated with the mixed P–N additives was 15.68–18.70 MJ/kg, which was lower than that of the pure P–N additive plate. Among mixed P–N additives, N,N′-piperazine bis(methylenephosphonic acid) (PIPEABP)/pyrophosphoric acid (PP)/4NH4+ (2:1) had the highest fire performance index (FPI) and lowest fire growth index (FGI). The fire risk of all the samples treated with the P–N additives except sample 2 is much smaller than that of untreated sample and it shows improved fire safety.

Heat release rate curves of the Pinus rigida specimens painted with the mixed phosphorus–nitrogen additive solutions at an external heat flux of 25 kW/m2.Figure optionsDownload as PowerPoint slide