Measurement of kinetics and thermodynamics of the thermal degradation for non-charring polymers

Abstract

A quantitative understanding of the processes that occur in the condensed phase of burning materials is critical for the prediction of ignition and growth of fires. A number of models have been developed to simulate these condensed phase processes. The main issue that remains to be resolved is the determination of parameters to be input to these models, which are formulated in terms of fundamental physical and chemical properties.This work is focused on developing and applying a systematic methodology for the measurement of kinetics and thermodynamics of the thermal degradation of polymers. Specifically, the polymers examined in this study are the following seven representative non-charring materials: poly(oxymethylene), poly(methyl methacrylate), high-impact polystyrene, polyamide 6,6, polypropylene, poly(lactic acid), and poly(acrylonitrile butadiene styrene). This methodology employs a simultaneous thermal analysis instrument capable of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). A numerical model is utilized to fit thermogravimetric data and obtain thermal degradation kinetics. This model is subsequently employed to analyze DSC heat flow and extract sensible, melting and degradation reaction heats. The extracted set of kinetic and thermodynamic parameters is shown to simultaneously reproduce TGA and DSC curves.