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- 2020 (4) (entfernen)
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- Cone calorimeter (2)
- Flame retardant (2)
- Polyurethane (2)
- Burning behavior (1)
- Fire behavior (1)
- Flammability (1)
- Flammschutz (1)
- Flexible PU foam (1)
- Foam (1)
- Polyurethan (1)
Organisationseinheit der BAM
Flexible polyurethane foams (FPUF) are easy to ignite and exhibit rapid flame spread. In this paper, the fire phenomena of two standard foam formulations containing tris (1,3-dichloro-2-propyl) phosphate (FR-2) and a halogen-freepoly (ethyl ethylene phosphate) (PNX), respectively, as flame retardants are compared. A multimethodological approach is proposed which combines standard fire tests as well as new investigatory approaches. The thermophysical properties of the foams were determined by thermogravimetric analysis (TG), reaction to small flames was studied by means of the limiting oxygen index (LOI) and UL 94 HBF test, and the burning behavior was investigated with the cone calorimeter. Further, temperature development in burning cone calorimeter samples was monitored using thermocouples, and rheological measurements were performed on pyrolyzed material, delivering insight
into the dripping behavior of the foams. This paper gives comprehensive insight into the fire phenomena of flame-retarded FPUFs that are driven by the two-step decomposition behavior of the foams. LOI and UL 94 HBF tests showed a reduced flammability and reduced tendency to drip for the flame-retarded foams. TG and cone calorimeter measurements revealed that the two-step decomposition behavior causes two stages during combustion, namely structural collapse and pool fire. The flame-retardant mode of action was identified to take place primarily during the foam collapse and be based mainly on flame inhibition. However, some condensed-phase action was been measured, leading to significantly increased melt viscosity and improved dripping behavior for foams containing PNX.
Polyurethanes (PU) represent one of the most versatile classes of plastics. They are processed and used as thermoplastic, elastomer, and thermoset. The requirements regarding flammability are correspondingly versatile. Depending on the material and the field of application, specific fire tests have to be fulfilled. This paper describes the different concepts used to fulfil these requirements by choosing the right raw materials and flame retardants.
Polyurethane (PU) bilden eine der vielseitigsten Klassen der Polymerwerkstoffe. Kein anderer Kunststoff wird sowohl als Thermoplast, als Elastomer wie auch als Duroplast verarbeitet und eingesetzt. Entsprechend vielfältig sind auch die Anforderungen an den Flammschutz. Je nach Material und Anwendung müssen spezifische Brandnormen erfüllt werden. Der vorliegende Aufsatz gibt einen Überblick über die verfügbaren Ansätze, um durch geeignete Auswahl der Rohstoffe und der Flammschutzmittel diese verschiedensten Anforderungen an das Brandverhalten zu erfüllen.
Rigid polyurethane foams (RPUFs) exhibit short times to ignition as well as rapid flame spread and are therefore considered to be hazardous materials. This paper focuses on the fire phenomena of RPUFs, which were investigated through a multimethodological approach. Water-blown polyurethane (PUR) foams without flame retardants (FRs) as well as waterblown PUR foams containing triethyl phosphate as a gas phase-active FR were examined. The aim of this study is to clarify the influence of the FR on the fire phenomena during combustion of the foams. Additionally, materials’ densitieswere varied to range from 30 to 100 kg/m3. Thermophysical properties were studied bymeans of thermogravimetry; fire behavior and flammability were investigated via cone calorimeter and limiting Oxygen index, respectively. During the cone calorimeter test, the temperature development inside the burning specimens was monitored with thermocouples, and cross sections of quenched specimens were examined visually, giving insight into the morphological changes during combustion.
The present paper delivers a comprehensive study, illuminating phenomena occurring during foam combustion and the influence of a FR active in the gas phase. The superior fire performance of flameretarded PUR foams was found to be based on flame inhibition, and on increased char yield leading to a more effective protective layer. It was proven that in-depth absorption of radiation is a significant factor for estimation of time to ignition. Cross sections investigated with the electron scanning microscope exhibited a pyrolysis front with an intact foam structure underneath. The measurement of temperature development inside burning specimens implied a shift of burning behavior towards that of non-cellular materials with rising foam density.