On the superposition of heat release rate for polymeric materials

Different materials will be put together for practical application. In fire risk assessment, the resultant heat release rate of the materials combination, not the heat release rate for a single type of materials has to be known. The resultant heat release rate of two materials mixed in different ratios will be studied in this paper. Polymethylmethacrylate PMMA and polycarbonate PC are taken as examples. The heat release rates of these samples mixed in varying ratios, but exposed to the same radiative heat flux, were measured by a cone calorimeter. The relative orientation of the sample is also investigated by placing PMMA in a vertical direction, and PC in a horizontal direction. It is found that simple addition formula by superposition is good enough to estimate the resultant heat release rate curves for horizontal arrangements. Results were further verified by full-scale burning tests in a new facility, the PolyU/HEU Assembly Calorimeter.