MEASURING THE SPECTRAL PROPERTIES OF POLYMERS AND USING THEM FOR FLAMMABILITY PREDICTIONS

The in-depth radiation absorption is a key mechanism in predicting ignition time and fire spread. To accurate estimation of in-depth absorption for polymers, their absorption coefficient should be measured spectrally. In this research, the spectrum of absorption coefficient for black PMMA is determined using spectroscopy for wavelength range of 0.25 to 25 𝜇𝑚. Due to spectral nature, mean absorption coefficient is changing with source temperature and thickness of the material. Hence, to increase the accuracy for pyrolysis simulations, different values of mean absorption coefficient should be applied. To show this in practice, a pyrolysis model is presented in this study that applies the variable mean absorption coefficient to predict ignition time for black PMMA. Using genetic algorithm for estimation of thermal conductivity and specific heat capacity, the model can predict ignition time for various heat fluxes with considered uncertainty.