Comparison of the thermal decomposition behavior of a non-fire retarded and a fire retarded flexible polyurethane foam with phosphorus and brominatedadditives

Thermogravimetric analysis was carried out to investigate the thermal decom position behavior of a commercial fire retarded (FR) and a non-fire retarde d (NFR) flexible polyurethane foam. The effects of the heating rate and the reaction atmosphere on the thermal decomposition process were studied at t hree different heating rates ranging from 5 degreesC/min to 20 degreesC/min in both nitrogen and air environment. Results from the time-of-flight seco ndary ion mass spectrometry (ToF SIMS) study revealed that the additives in the FR foam were phosphorus and brominated compounds. The measurements by means of colorimetric method further certified that the concentrations of p hosphorus and bromine in the FR foam sample were 0.08 wt% and 1.4 wt% respe ctively. From the thermogravimetric (TG) and the derivative thermogravimetr ic (DTG) curves, it was seen that the thermal decomposition processes of bo th the FR and the NFR foams followed a two-step reaction in nitrogen. Howev er, the thermal decomposition processes followed a three-step reaction in a ir. The thermal analysis results showed that the flame retardant additives of phosphorus and brominated compounds acted not only in the gas phase but also in the solid phase. Furthermore, the flame retardant additives decreas ed the thermal stability and increased the char formation in the temperatur e ranging from 300 degreesC to 400 degreesC, which, commonly, is the temper ature range for smoldering combustion in this kind of foam material. From t he kinetic parameters estimated from the TG and the DTG curves, it was seen that the activation energies of the flexible polyurethane foams were very sensitive to the temperature and were also influenced significantly by the flame retardant additives.