Experimental and Numerical Study of the Thermal Degradation of PMMA

Abstract

Thermal degradation of PMMA subjected to a radiant heat flux was studied both experimentally and numerically . Very accurate measurements of mass loss rate and temperature profiles were performed for three constant heat fluxes: 1.5,2.3 and 3.0 W·cm-'. The results show that the mass loss rate cannot be directly related to the surface temperature and a. contribution of the sub-surface region of the sample to the rate of gasification must be taken into account in a thermal degradation model. A heat source term was introduced in the conduction equation and a kinetic equation was used to locally calculate the mass loss rate in each slab of the solid. The density and the thermal conductivity of the material were assumed temperature independent while for the specific heat the values measured by differential scanning calorimetry in the range 20-400·C were retained. The predictions of the model are in very close agreement with the experimental results for the evolution with time of both the temperature profile in the solid and the mass loss rate.

Pyrolysis modeling, sensitivity analysis, and optimization techniques for combustible materials: A review

“…In 1987, Vovelle et al [68] developed a model for the prediction of the mass loss rate of PMMA exposed to a radiant heat flux. The model was also similar to Bamford's model in that it was a combination of the heat transfer equation and the Arrhenius equation assuming a first order reaction.…”

“…Genetic algorithms have been applied in other fields such as turbulent reacting flows for the optimization of reaction rate coefficients and they were found to be numerically robust and efficient as well as being flexible and easy to use [68]. In 2001, Şahin et al used genetic algorithms (GA) to determine the kinetic parameters from thermogravimetric analysis of ammonium pentaborate.…”