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Aspects of the Fire Behavior of Thermoplastic Materials.



Thomas J. Ohlemiller, John R. Shields


Thermoplastic polymers pose unique new challenges (resulting from the movement of burning melt material) for the understanding and control of fire growth on objects that incorporate them. Both full density thermoplastics such as polypropylene and polystyrene, as well as low density polyurethane foams are examined in this study, which has two overall goals: (1) assessment of potential test methods for quantitatively judging the flammability hazard of a thermoplastic (focused most specifically on polyurethane foams) and (2) fostering the development and validation of a model of fire growth over generic configurations of thermoplastic materials suggested by their end product use (particularly upholstered furniture). One such configuration is that used in the flammability test method, but early model development steps emphasize simpler configurations and materials. A critical aspect of modeling these materials is an adequate description of the viscosity of the polymer melt as a function of temperature; the viscosity can vary by several orders of magnitude. A procedure for deriving an empirical description of viscosity for full density thermoplastics, dependent only on temperature, is given but it requires extrapolation of melt viscosity out to burning temperatures. The procedure may be stymied by the complex behavior of polyurethane foam melts, indicating a need for further work. Gasification kinetics of the material, also needed in the fire growth model, are derived here from thermogravimetry for four full density thermoplastics. The more complex degradation behavior of polyurethane foam requires further work to derive these kinetics. The modeling process has been proceeding in stages of increasing complexity in conjunction with an outside contractor. The current stage focuses on two-dimensional, non-flaming melting plus gasification at heat fluxes comparable to those seen in fire growth. The present study has produced data on four full density thermoplastics and sever
Technical Note (NIST TN) - 1493
Report Number


thermoplastics, fire behavior, fire growth, polypropylene, polystyrene, polyurethane foams, test methods, flammability, heat release rate, upholstered furniture, flammability tests, viscosity, temperature, thermogravity, experiments, gasification, kinetics, flammability testing, furniture calorimeters


Ohlemiller, T. and Shields, J. (2008), Aspects of the Fire Behavior of Thermoplastic Materials., Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 23, 2024)
Created January 1, 2008, Updated November 10, 2018