Influence of thermal behavior of phosphorus compounds on their flame retardant effect in PU rigid foam

Phosphorus‐containing compounds have been widely used as flame retardants for polyurethane rigid foam (PURF). In this work, a number of phosphorus compounds were utilized and studied as flame retardants for PURF, including ammonium polyphosphate, pentaerythritol phosphate, triethyl phosphate, and dimethyl methyl phosphonate. The thermal behavior of flame retardants was thoroughly investigated, such as degradation, vaporization, and the properties of degraded products. The influence of thermal behavior of phosphorus flame retardants on PURF was examined and analyzed. The results indicated that the effect of flame retardant was highly related to their thermal behavior. Phosphorus compounds for gas phase flame retardants were very effective in decreasing the heat release rate and increase limited oxygen index of PURF, while condensed phase flame retardants showed better comprehensive flame retardant effect, such as reducing the toxicity of combustion product. Copyright © 2015 John Wiley & Sons, Ltd.