Fire properties of combustible materials from unsteady burning

Six (6) polymers, 2–6 mm thick, were tested in a cone calorimeter by a standard method at various external heat fluxes (irradiance). The ratio of the effective heat of combustion to the effective heat of gasification per unit mass of volatile fuel, Hc/Hg, also known at the heat release parameter (HRP) or combustibility ratio, was obtained as a sample average for unsteady burning at multiple heat fluxes. Global values of Hc/Hg from unsteady burning are biased by heat flux dependent losses during the test, but are generally within the range of literature values for steady burning. Linearization of the unsteady energy balance provides a parameter (γ) that is the efficiency with which radiant energy is converted to combustion energy. This parameter is in the range, γ = 0.6–0.9, for the polymers of this study.