Development of pyrolysis models for charring polymers

Controlled atmosphere, radiation-driven gasification experiments were conducted on a series of synthetic polymers including poly(acrylonitrile butadiene styrene), poly(ethylene terephthalate), poly(methyl methacrylate)-poly(vinyl chloride) alloy (Kydex) and polyetherimide. Mass loss rate and non-radiated surface temperature of coupon-sized material samples were measured simultaneously and recorded as a function of time. These temperature data were combined with the results of broadband radiation absorption measurements and previously conducted thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to characterize the transport of thermal energy inside the gasifying materials through inverse modeling. Subsequently, complete pyrolysis models, based on the kinetics and thermodynamics of the thermal decomposition derived from the TGA and DSC experiments, were formulated and employed to predict the mass loss rate histories obtained at 30-90 kW m−2 of external radiant heat flux simulating fire exposure. Satisfactory predictions were obtained for all materials with the exception of polyetherimide, which highly intumescent behavior introduced large uncertainties in the gasification conditions.