Modeling study on the combustion of intumescent fire-retardant polypropylene

Abstract

The heat transfer and burning behavior of intumescent fire-retardant polypropylene were studied by cone calorimeter at heat flux levels of 50 kW·m-2 to establish an essential physical model for the intumescence process in fire. A mathematical model for the burning process of fire-retardant intumescent polymer was put forward based on the assumption that an intumescent front existed between the char layer and virgin layer. The model emphasizes the thermodynamic aspect of the intumescence process and a corresponding submodel is presented. Meanwhile the thicknesses and mass loss rates of the intumescent polypropylene during burning were measured for the validation of the modeling results. Thermal conductivity and heat capacity of polymer material were also measured as input parameters of the model. The validation results showed that the intumescent thicknesses and mass loss rates predicted by the model were in good agreement with the experimental results. The model was also used to predict the temperature distribution across the sample thickness during burning. The study shows that the present model can appropriately describe the intumescent behavior of the polymer and numerically predict its mass loss rates and temperature distribution in fire. © BME-PT and GTE.