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Burning Rate and Flame Heat Flux for PMMA in the Cone Calorimeter.


pdf icon Burning Rate and Flame Heat Flux for PMMA in the Cone Calorimeter. (2959 K)
Rhodes, B. T.

NIST GCR 95-664; Thesis; 125 p. December 1994.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD
Order number: PB95-216990

Keywords:

cone calorimeters; burning rate; heat flux; polymethyl methacrylate; ignition; experiments; mass loss; heating; thermoplastics; small scale fire tests

Abstract:

Ignition and burning rate data are developed for thick (25 mm.) black Polycast PMMA in a Cone Calorimeter heating assembly. The objective is to establish a testing protocol that will lead to the prediction of ignition and burning rate from Cone data. This is done for a thermoplastic like PMMA. For black PMMA, ignition temperatures of 250 to 350 deg C and vaporization temperatures of approximately 325 to 380 deg C were measured over irradiance levels of 15 to 65 kW/m(2). The incident flame heat flux, for irradiation levels of 0 to 75 kW/m(2), is found to be approximately 37 kW/m(2) for black PMMA. Its constancy is shown due to the geometry of the Cone flame. Also, this flame is shown to be nearly transparent for Cone irradiance (>90%). The heat of gasification of the black PMMA used is found to be approximately 2.8 kJ/g; higher than other values reported for PMMA. This is believed to be due to differences in molecular structure or pigmentation effects and the types of PMMA tested. A burning rate model is demonstrated to yield good accuracy (>80%) in comparison to measured transient values.