TY - JOUR A1 - Schartel, Bernhard A1 - Günther, Martin T1 - Flame retardancy of polyurethanes N2 - 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. KW - Polyurethane KW - Flame retardant KW - Foam KW - Flammability KW - Pyrolysis KW - Cone calorimeter PY - 2020 VL - 17 IS - 1 SP - 44 EP - 48 PB - Dr. Gupta AN - OPUS4-50737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günther, Martin A1 - Lorenzetti, Alessandra A1 - Schartel, Bernhard T1 - Fire phenomena of rigid polyurethane foams N2 - This work investigates the fire phenomena of rigid polyurethane foams (RPUF) in detail. To elucidate structure-property relationships systematically varied sets of foams were prepared. RPUF were synthesized with different densities using water and pentane as blowing agent. What is more, a flame retarded RPUF and rigid polyisocyanurate-polyurethane foams were examined. The comprehensive understanding of the processes taking place during combustion is the foundation of customized development of successful flame retardant approaches. Advanced cone calorimeter investigations provide insight into the fire behavior under forced flaming conditions. Thermocouples in the inside of specimens give information about the temperature gradient and temperature of the pyrolysis zone during combustion. Furthermore, fire phenomena were characterized using SEM, LOI and thermal analysis. By using a multi-methodological approach and systematically varied sets of foam materials, new insights into the burning of RPUF were won. The detailed knowledge of fire phenomena is essential for future development of tailored flame retardant strategies for RPUF. T2 - 15th International Conference on Advances in Foam Materials & Technology, FOAMS 2017 CY - Bayreuth, Germany DA - 11.10.2017 KW - Foam KW - Cone calorimeter KW - Flame retardancy KW - Fire behaviour KW - Polyurethane PY - 2017 AN - OPUS4-42755 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gómez-Fernández, S. A1 - Günther, Martin A1 - Schartel, Bernhard A1 - Corcuera, M. A. A1 - Eceiza, A. T1 - Impact of the combined use of layered double hydroxides, lignin and phosphorous polyol on the fire behavior of flexible polyurethane foams N2 - Flexible polyurethane foams with densities of 40 ± 2 kg m−3 were prepared by combining different ecofriendly fillers such as layered double hydroxides (LDH) and kraft lignin (a byproduct of the pulp and paper industry) with a phosphorous polyol (E560) in order to study their effect on the mechanical performance and fire behavior of the foams. Two series of foams were prepared, some containing lignin or LDH separately, and some with a combination of both: one of the series was prepared without E560 (0E foam series) and the other with 5 parts per hundred of E560 polyol (5E series). The use of fillers resulted in increased viscosity of the reactive mixture, requiring higher blowing agent content in order to hold the density of the foams constant. It was observed that urea phase segregation was favored in the series of 0E foams due to their lower viscosity than the 5E series. This had consequent effects on the resilience, compression force deflection and compression set of these foams. In terms of fire behavior it was observed that while the limiting oxygen index decreased, cone calorimeter results showed that the combination of lignin, LDH and E560 decreased the heat release of the foams. In addition, the combination of fillers and E560 contributed to increase the viscosity of the pyrolysis products, preventing the dripping of the molten polymer, which is a key factor in flame propagation towards adjacent objects in fire scenarios. KW - Ligning KW - Foam KW - Flexible polyurethane foam KW - Flame retardant PY - 2018 SN - 0926-6690 VL - 125 SP - 346 EP - 359 PB - Elsevier B.V. AN - OPUS4-45971 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Günther, Martin A1 - Lorenzetti, A. A1 - Schartel, Bernhard T1 - Fire Phenomena of Rigid Polyurethane Foams N2 - Rigid polyurethane foams (RPUFs) typically exhibit low thermal inertia, resulting in short ignition times and rapid flame spread. In this study, the fire phenomena of RPUFs were investigated using a multi-methodological approach to gain detailed insight into the fire behaviour of pentaneand water-blown polyurethane (PUR) as well as pentane-blown polyisocyanurate Polyurethane (PIR) foams with densities ranging from 30 to 100 kg/m3. Thermophysical properties were studied using thermogravimetry (TG); flammability and fire behaviour were investigated by means of the limiting oxygen index (LOI) and a cone calorimeter. Temperature development in burning cone calorimeter specimens was monitored with thermocouples inside the foam samples and visual investigation of quenched specimens’ cross sections gave insight into the morphological changes during burning. A comprehensive investigation is presented, illuminating the processes taking place during foam combustion. Cone calorimeter tests revealed that in-depth absorption of radiation is a significant factor in estimating the time to ignition. Cross sections examined with an electron scanning microscope (SEM) revealed a pyrolysis front with an intact foam structure underneath, and temperature measurement inside burning specimens indicated that, as foam density increased, their burning behaviour shifted towards that of solid materials. The superior fire performance of PIR foams was found to be based on the cellular structure, which is retained in the residue to some extent. KW - Foam KW - Polyurethane KW - Fire behaviour KW - Flammability PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-465577 SN - 2073-4360 VL - 10 IS - 10 SP - 1166-1 EP - 1166-22 PB - MDPI AN - OPUS4-46557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Günther, Martin A1 - Lorenzetti, A. A1 - Schartel, Bernhard T1 - Bubbles And Collapses: Fire Phenomena Of Rigid Polyurethane Foams N2 - Rigid polyurethane foams (RPUF) are widely used in industry and daily life because of their outstanding mechanical and thermal insulating properties. While their convenient mechanical characteristics predestine these materials for shock absorption, their low thermal conductivity is responsible for their excellent thermal insulation properties. A principal characteristic affecting not only the use properties, but also the burning behaviour, is the density of RPUF. In case of fire, cellular polymers like RPUF behave differently from bulk materials. The reason for their comparatively high ignitability is the high rate of temperature rise on the surface when exposed to heat, which is due to their cellular structure and characterised as low thermal inertia. The heat build-up on the surface results in a short time to ignition. Therefore foams are able to develop fire and large amounts of smoke within a short period of time. Even though their fire load is quite low because of their low density, their heat release rate is high. These burning properties are not only a consequence of the chemical consistence of such materials, but also a result of their morphology. The aim of the work is to investigate the fire phenomena of RPUF. Characterised by simultaneous physical and chemical processes which interact, depend, and compete with each other, the combustion of RPUF is a highly complex occurrence. Therefore it is necessary to study all aspects in detail. The fire phenomena that were examined are gasification, liquefaction, charring and structural integrity as well as collapse. The melting of cellular polymers and dripping of pyrolysis products, together with the ability to form pool fires, are the main hazards in fires involving foams. Structural collapse via melting or decomposition, or the retention of the foam’s morphology through charring, are the main characteristics of their burning behaviour. Cellular structure is a further important factor influencing the materials’ response to fire, and deserves examination in greater depth. Since the cells in closed-cell foam are filled with the blowing agent used to produce the material, and this blowing agent can be inert (carbon dioxide) or highly flammable (pentane), this component also affects the burning properties and will be investigated. Examination of the influence of the macroscopic morphology, namely the cell size and thickness of cell walls, will contribute to the study. In order to provide comprehensive insight into the processes taking place during combustion, and to elucidate structure-property relationships, a set of foams with systematically varied properties was prepared. RPUF was obtained using water and pentane as a blowing agent. Besides RPUF, a flame-retarded RPUF and rigid polyisocyanurate-polyurethane foam were examined, since these foams are known for their higher stability from a thermodanymic point of view. As a flame retardant active in the gas phase, triethylphosphate was used. Using a multi-methodological approach, the complex interaction of fire phenomena was studied in detail. Cone calorimeter measurements provide insight into fire behaviour under forced-flaming conditions. They were carried out in an horizontal and a vertical orientation to account for the effects of melt flow and dripping. Sample-holders were equipped with glass windows to monitor the materials’ response to forced-flaming conditions with a video camera. Thermocouples were inserted into the specimens, giving information about the temperature gradient in the inside of the sample and the temperature of the pyrolysis zone during combustion. Changes in the morphology and thickness of the pyrolysis zone were examined using a hot-stage microscope, as well as SEM images of cross-sections of quenched foam specimens. The determination of the Oxygen Index and the use of thermogravimetry measurements rounded out the investigation. T2 - FRPM 2017, 16th European Meeting on Fire Retardant Polymeric Materials CY - Manchester, UK DA - 03.07.2017 KW - Foam KW - Polyurethane KW - Polyisocyanurate PY - 2017 AN - OPUS4-40950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -