Effect of inorganic additive flame retardant on fire hazard of polyurethane exterior insulation material

摘要

The effect of inorganic additive flame retardant on fire hazard of polyurethane exterior insulation material was experimentally investigated by the cone calorimeter (Cone) and thermal gravimetric-differential thermal analysis. The aluminum trihydrate (ATH) and magnesium hydroxide (MDH) were considered as the inorganic additive flame retardants in the experiments. The results indicated that compared to pure rigid polyurethane foam (RPUF), the RPUF containing inorganic flame retardant could significantly enhance fire resistance and thermal stability. Especially for RPUF, the ratio of MDH and ATH was 1:3, the ignition delay time was extended for about 14.33s as well as the values of peak heat release rate and the total heat release were reduced by about 50.79kWm(-2) and 2.60MJm(-2). Also, the peak values of the carbon monoxide release rate were decreased to 0.0096gs(-1). Further, the decomposition process of the RPUFs in nitrogen and air was compared and analyzed. It was found that they could be divided into two stages and three stages, respectively, and small fluctuations of the second stage in air were corresponded to the decomposition of ATH and MDH. Besides, the compressive properties were proved to decrease with the increased additive amount of the metal hydroxides. Based on the experimental results and the classic dynamics methods, the activation energy (E) and the pre-exponential factor (A) were obtained and it turned out that the addition of inorganic flame retardant could enlarge the values of E and A, which helped to reduce the fire hazard.