Effect of ammonium polyphosphate/cobalt phytate system on flame retardancy and smoke & toxicity suppression of rigid polyurethane foam composites

Rigid polyurethane foam/ammonium polyphosphate/cobalt phytate (RPUF/APP/PA-Co) composites were prepared by one-step water-blown method using ammonium polyphosphate (APP)/cobalt phytate (PA-Co) as a flame retardant system. The char residue of RPUF/APP/PA-Co increased significantly than that of RPUF, indicating that the thermal stability of composites was enhanced. Cone calorimetry and smoke density tests showed that when 40 phr APP and 10 phr PA-Co were added, the total heat release and smoke release of RPUF/APP40/PA-Co10 composite decreased significantly. TG-IR test confirmed that APP/PA-Co could significantly inhibit the release of flammable gases (hydrocarbons, esters) and toxic gases (aromatic compounds, isocyanate, CO, HCN,) of RPUF/APP/PA-Co composites and improve the fire resistance of composites. SEM-EDS, Raman spectra and FTIR were applied to investigate the char residues of composites. The results showed that APP/PA-Co loading was beneficial to the generation of dense char layer with high degree of graphitization and reducing the release of combustible substances and smoke of composites.