One-dimensional modeling approaches for the piloted ignition of poly (methyl methacrylate)

Effects of the PMMA Molecular Weight on the Thermal and Thermo-Oxidative Decomposition as the First Chemical Stage of Flaming Ignition

“…For the development of predictive models, chemical and physical processes should be described with accuracy levels depending on specific requirements for the predictions. In accordance with the literature review reported in [7,8], the first class of PMMA ignition models consists of condensed-phase descriptions coupled with empirical ignition criteria [9][10][11][12][13][14][15][16][17][18][19]. Another model class is based on descriptions of both the condensed and gas phases [7,8,[20][21][22][23][24][25][26][27][28][29], which do not require the use of empirical criteria.…”

“…In accordance with the literature review reported in [7,8], the first class of PMMA ignition models consists of condensed-phase descriptions coupled with empirical ignition criteria [9][10][11][12][13][14][15][16][17][18][19]. Another model class is based on descriptions of both the condensed and gas phases [7,8,[20][21][22][23][24][25][26][27][28][29], which do not require the use of empirical criteria. These include both simple unsteady onedimensional models, which give quantitative information on the main global parameters (e.g., ignition delay time, surface temperature, and volatile mass flux at ignition), and more advanced CFD formulations.…”

“…In fact, significant variations are observed among the literature values. To quantify the influences of such variability on ignition predictions, an extensive sensitivity analysis has been recently carried out for a one-dimensional solid-gas phase model [7]. For both the spontaneous and the piloted cases, the highest sensitivity concerns the kinetics of polymer decomposition [8].…”

“…For both the spontaneous and the piloted cases, the highest sensitivity concerns the kinetics of polymer decomposition [8]. It is interesting to observe that despite the improvements in the mathematical description of the flaming ignition of PMMA when the empirical criteria of the models [9][10][11][12][13][14][15][16][17][18][19] are substituted by rigorous formulations of conservation equations for mass and energy coupled with combustion kinetics by models [7,8,[20][21][22][23][24][25][26][27][28][29], a global single-step mechanism is always used for the polymer decomposition into monomers. This kinetics is applicable only to low molecular weight samples.…”

“…It has been clearly pointed out [30] that the PMMA decomposition kinetics is influenced by its chemical properties, such as molecular weight, tacticity, branching degrees, and polymerization conditions (for instance, anionic or free radical method). In particular, the PMMA molecular weight determines important features of the decomposition mechanism that turns from a one-stage global reaction (low molecular weight) [7,[31][32][33] into a multistep process (high molecular weight) [17,34]. However, none of the literature models combine multistep decomposition kinetics with the description of either solid phase physical processes only [9][10][11][12][13][14][15][16][17][18][19] or both solid and gas processes [7,8,[20][21][22][23][24][25][26][27][28][29].…”