Assessment of the predictive capabilities of a solid-gas model for poly (methyl methacrylate) ignition

A sensitivity analysis is carried out to all inputs of a one-dimensional solid-gas model for the spontaneous and the piloted ignition of thick poly (methyl methacrylate) under a constant radiative heat flux, which was previously subjected to experimental validation (Fire Saf. J. 129, 103566, 2022 [1]). For both ignition modes, the highest sensitivity is observed for the kinetics of polymer decomposition and monomer combustion whose rates are varied within literature ranges of 5–7 and 4-6 orders of magnitude, respectively. The strongest effects are for the decomposition kinetics, though they tend to decrease as the radiative heat is increased (25kW/m2-150 kW/m2). The piloted ignition times predicted with the slowest and the fastest decomposition kinetics are longer and shorter by about 255%–85 % and 45%–20 %, respectively, compared with the reference case. Slightly lower values are predicted for spontaneous ignition. Maximum deviations of about +10 % and −30 % are predicted with the slowest and the fastest combustion kinetics. Hence the polymer properties and the decomposition atmosphere are key issues for quantitative predictions and should be properly considered. The influences of the solid- and gas-phase radiation absorption coefficients and the spark temperature are also discussed for variations in the range of literature values.