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- 2010 (2) (entfernen)
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- Englisch (2)
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- Pyrolysis (2) (entfernen)
On the basis of two examples, temperature measurements are proposed within burning polymer specimen during the cone calorimeter test; especially to gain deeper insight into the actual pyrolysis conditions and flame retardancy mechanism. The heating and pyrolysis within a poly(methyl methacrylate) specimen were characterized, discussing the characteristic maximum heating rates (165-90°Cmin-1 decreasing with depth within the specimen and >275°Cmin-1 at the initial surface), pyrolysis temperature (454-432°C decreasing in accordance with decreasing heating rates), thickness of the pyrolysis zone (0.5-1.3 mm) and its velocity (1.2-2.1 mm min-1) as a function of sample depth and burning time. Thermally thick behaviour corresponds to a pyrolysis zone thickness of 0.74 mm and a velocity of 1.51 mm min-1 and occurs until the remaining specimen thickness is less than 8 mm. The shielding effect against radiation occurring in a layered silicate epoxy resin nanocomposite was investigated. It is the main flame retardancy effect of the silicate-carbon surface layer formed under fire. The reradiation from the hot surface is increased by a factor of around 4-5 when an irradiance of 70kWm-2 is applied. The energy impact into the pyrolysis zone is crucially reduced, resulting in a reduction of fuel production and thus heat release rate.