Synergy between manganese phytate and expandable graphite on thermal stability and combustion behavior of rigid polyurethane foam

Abstract Rigid polyurethane foam (RPUF) modified by self‐made manganese phytate (MnPa) and expandable graphite (EG) has been prepared successfully. The thermal stability and combustion behavior of the modified RPUFs (MEPUF) have been studied using the thermogravimetric analysis, pyrolysis kinetics analysis, smoke density analysis, limiting oxygen index (LOI), and UL‐94 level test. When compared to MEPUF1 (MnPa/EG = 3/1), MEPUF2 (MnPa/EG = 1/1) had a 9.1°C higher initial decomposition temperature and had a greater activation energy. Additionally, the smoke density experiment demonstrated that the light transmittance of MEPUF2 increased by 5.1% compared with MEPUF1 in 0–70s and the LOI of MEPUF2 reached 23%. The current investigation indicated that MEPUF2 had better thermal stability and flame retardancy.