TY - JOUR A1 - Wawrzyn, Eliza A1 - Schartel, Bernhard A1 - Seefeldt, Henrik A1 - Karrasch, A1 - Jäger, Christian T1 - What reacts with what in bisphenol A polycarbonate/silicon rubber/bisphenol A bis(diphenyl phosphate) during pyrolysis and fire behavior? JF - Industrial & engineering chemistry research N2 - The pyrolysis and flame retardancy of a bisphenol A polycarbonate/silicon rubber/bisphenol A bis(diphenyl phosphate) (PC/SiR/BDP) blend were investigated and compared to those of PC/BDP and PC/SiR. The impact modifier SiR consists mainly of poly(dimethylsiloxane) (PDMS > 80 wt %). The pyrolysis of PC/SiR/BDP was studied by thermogravimetry (TG), TG–FTIR to analyze the evolved gases, and a Linkam hot stage cell within FTIR as well as 29Si NMR and 31P NMR to analyze the solid residue. The fire performance was determined by PCFC, LOI, UL 94, and a cone calorimeter under different external irradiations. The fire residues were studied by using ATR-FTIR as well as the additional binary systems PC + PDMS, PC + BDP, and BDP + PDMS, focusing on the specific chemical interactions. The decomposition pathways are revealed, focusing on the competing interaction between the components. Fire retardancy in PC/SiR/BDP is caused by both flame inhibition in the gas phase and inorganic-carbonaceous residue formation in the condensed phase. The PC/SiR/BDP does not work as well superimposing the PC/SiR and PC/BDP performances. PDMS reacts with PC and BDP, decreasing BDP's mode of action. Nevertheless, the flammability (LOI > 37%, UL 94 V-0) of PC/SiR/BDP equals the high level of PC/BDP. Indeed, SiR in PC/SiR/BDP is underlined as a promising impact modifier in flame-retarded PC/impact modifier blends as an alternative to highly flammable impact modifiers such as acrylonitrile–butadiene–styrene (ABS), taking into account that the chosen SiR leads to PC blends with a similar mechanical performance. KW - PC KW - BDP KW - PDMS KW - Flame retardancy KW - Flammability KW - Decomposition KW - Pyrolysis PY - 2012 DO - https://doi.org/10.1021/ie201908s SN - 0888-5885 SN - 1520-5045 VL - 51 IS - 3 SP - 1244 EP - 1255 PB - American Chemical Society CY - Washington, DC AN - OPUS4-25460 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wawrzyn, Eliza A1 - Schartel, Bernhard A1 - Ciesielski, M. A1 - Kretzschmar, B. A1 - Braun, Ulrike A1 - Döring, M. T1 - Are novel aryl phosphates competitors for bisphenol A bis(diphenyl phosphate) in halogen-free flame-retarded polycarbonate/acrylonitrile-butadiene-styrene blends? JF - European polymer journal N2 - The reactivity of the flame retardant and its decomposition temperature control the condensed-phase action in bisphenol A polycarbonate/acrylonitrile–butadiene–styrene/polytetrafluoroethylene (PC/ABSPTFE) blends. Thus, to increase charring in the condensed phase of PC/ABSPTFE + aryl phosphate, two halogen-free flame retardants were synthesized: 3,3,5-trimethylcyclohexylbisphenol bis(diphenyl phosphate) (TMC-BDP) and bisphenol A bis(diethyl phosphate) (BEP). Their performance is compared to bisphenol A bis(diphenyl phosphate) (BDP) in PC/ABSPTFE blend. The comprehensive study was carried out using thermogravimetry (TG); TG coupled with Fourier transform infrared spectrometer (TG-FTIR); the Underwriters Laboratory burning chamber (UL 94); limiting oxygen index (LOI); cone calorimeter at different irradiations; tensile, bending and heat distortion temperature tests; as well as rheological studies and differential scanning calorimeter (DSC). With respect to pyrolysis, TMC-BDP works as well as BDP in the PC/ABSPTFE blend by enhancing the cross-linking of PC, whereas BEP shows worse performance because it prefers cross-linking with itself rather than with PC. As to its fire behavior, PC/ABSPTFE + TMC-BDP presents results very similar to PC/ABSPTFE + BDP; the blend PC/ABSPTFE + BEP shows lower flame inhibition and higher total heat evolved (THE). The UL 94 for the materials with TMC-BDP and BDP improved from HB to V0 for specimens of 3.2 mm thickness compared to PC/ABSPTFE and PC/ABSPTFE + BEP; the LOI increased from around 24% up to around 28%, respectively. BEP works as the strongest plasticizer in PC/ABSPTFE, whereas the blends with TMC-BDP and BDP present the same rheological properties. PC/ABSPTFE + TMC-BDP exhibits the best mechanical properties among all flame-retarded blends. KW - Polycarbonate (PC) KW - Aryl phosphate KW - Flame retardancy KW - Pyrolysis KW - PC/ABS PY - 2012 DO - https://doi.org/10.1016/j.eurpolymj.2012.06.015 SN - 0014-3057 SN - 1873-1945 VL - 48 IS - 9 SP - 1561 EP - 1574 PB - Elsevier CY - Oxford AN - OPUS4-26292 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Despinasse, Marie-Claire A1 - Schartel, Bernhard T1 - Influence of the structure of aryl phosphates on the flame retardancy of polycarbonate/acrylonitrile-butadiene-styrene JF - Polymer degradation and stability N2 - The impact of the chemical structure of four different aryl bisphosphates on the flame retardancy of bisphenol A polycarbonate/acrylonitrile–butadiene–styrene blends (PC/ABS) was investigated. The impact of the bridging unit was studied, by comparing bisphenol A bis(diphenyl phosphate) BDP with biphenyl bis(diphenyl phosphate) BBDP and hydroquinone bis(diphenyl phosphate) HDP; as well as the influence of an aromatic substitution by comparing BBDP with biphenyl bis (di-2,6-xylyl phosphate) BBXP. The blends were investigated in terms of pyrolysis (thermogravimetry TG, TG coupled with Fourier transformed infrared spectroscopy (FTIR) and mass spectrometry (MS)) and fire performance (cone calorimeter, LOI, UL 94). The decomposition temperature of the flame retardant is a main parameter enabling a condensed phase interaction with PC decomposition products. The phosphate esters reacting with phenolic groups during pyrolysis were shown to increase cross-linking and reduce the hydrolysis/alcoholysis of the carbonate group. Variation of the aromatic substitution with the use of biphenyl bis (di-2,6-xylyl phosphate) led to reduced performance, highlighting the importance of the reactivity of the flame retardant with the decomposing PC. KW - Bisphenol A polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) KW - Flame retardancy KW - Flammability KW - Phosphate esters KW - Pyrolysis PY - 2012 DO - https://doi.org/10.1016/j.polymdegradstab.2012.07.005 SN - 0141-3910 SN - 1873-2321 VL - 97 IS - 12 SP - 2571 EP - 2580 PB - Applied Science Publ. CY - London AN - OPUS4-26969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Despinasse, Marie-Claire A1 - Schartel, Bernhard T1 - Aryl phosphate-aryl phosphate synergy in flame-retarded bisphenol A polycarbonate/acrylonitrile-butadiene-styrene JF - Thermochimica Acta N2 - The pyrolysis and fire performance of bisphenol A polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) flame-retarded by a mixture of two aryl bisphosphates were investigated by thermogravimetry-coupled with FTIR, oxygen index (LOI), UL 94 and cone calorimeter. Both flame retardants, bisphenol A bis (diphenyl phosphate) BDP and hydroquinone bis (diphenyl phosphate) HDP, show gas-phase and condensed-phase actions. When mixed together at different ratios, a synergy is observed in terms of pyrolysis and fire residues as well as in effective heat of combustion (THE/ML). The synergisms were quantified and confirmed mathematically by the evaluation of the synergistic effect index (SE). All LOI values for the flame-retarded blends are between 29% and 32%, as opposed to 23% for PC/ABS, and UL94 testing results in V-0 at 1.6 mm instead of HB. Investigations on the binary system BDP + HDP reveal that BDP and HDP interact with each other, yielding stable intermediate products which are proposed to increase the thermal stability of the PC/ABS + BDP/HDP blends. Oligomeric phosphate esters are presumed to form via transesterification. KW - Flame retardancy KW - PC/ABS KW - Pyrolysis KW - Aryl phosphate KW - Synergy KW - Combustion PY - 2013 DO - https://doi.org/10.1016/j.tca.2013.04.006 SN - 0040-6031 SN - 1872-762X VL - 563 SP - 51 EP - 61 PB - Elsevier CY - Amsterdam AN - OPUS4-28515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Perret, Birgit A1 - Dittrich, Bettina A1 - Ciesielski, M. A1 - Krämer, J. A1 - Müller, P. A1 - Altstädt, V. A1 - Zang, L. A1 - Döring, M. T1 - Flame retardancy of polymers: the role of specific reactions in the condensed phase JF - Macromolecular materials and engineering N2 - Condensed-phase mechanisms play a major role in fire-retardant polymers. Generations of development have followed the concept of charring to improve fire properties. Whereas the principal reactions are believed to be known, the specific description for multicomponent systems is lacking, as is the picture across different systems. A two-step approach is proposed in general, and also presented in greater detail. The second step covers the specific reactions controlling charring, whereas the actual reactants are provided in the preceding step. This model consistently incorporates the variety of structure–property relationships reported. A comprehensive case study is presented on seven phosphorus flame retardants in two epoxy resins to breathe life into the two-step approach. KW - Charring KW - Epoxy KW - Flame retardancy KW - Pyrolysis KW - Thermogravimetric analysis (TGA) PY - 2016 DO - https://doi.org/10.1002/mame.201500250 SN - 1438-7492 SN - 1439-2054 VL - 301 IS - 1 SP - 9 EP - 35 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-35273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Wilkie, Charles A. A1 - Camino, Giovanni T1 - Recommendations on the scientific approach to polymer flame retardancy: Part 1—Scientific terms and methods JF - Journal of Fire Sciences N2 - The correct use of scientific terms, performing experiments accurately, and discussing data using unequivocal scientific concepts constitute the basis for good scientific practice. The significance and thus the quality of scientific communication rely on the proper use of terms and methods. It is the aim of this two-part article to support the community with recommendations for discussing the flame retardancy of polymers by addressing some of the most relevant points. The first article (part one of two) clarifies some scientific terms and, in some cases, such as for ‘‘pyrolysis,’’ ‘‘thermal decomposition,’’ and ‘‘fire resistance,’’ critically discusses their definitions in the field of fire science. Several comments are made on proper fire testing and thermal analysis, including some thoughts on uncertainty in fire testing. The proper use of distinct concepts in flame retardancy is discussed briefly in the subsequent second article (part two). This article tries to Balance imparting background on the subject with recommendations. It encourages to check scientific practice with respect to communication and applying methods. KW - Pyrolysis KW - Fire testing KW - Char KW - Flame retardant KW - Flammability KW - Fire property PY - 2016 DO - https://doi.org/10.1177/0734904116675881 SN - 0734-9041 SN - 1530-8049 VL - 34 IS - 6 SP - 447 EP - 467 PB - SAGE AN - OPUS4-38115 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard A1 - Dittrich, Bettina A1 - Hofmann, D. A1 - Wartig, K.-A. A1 - Mülhaupt, R. T1 - Born in fire to kill fire – graphene in flame retardant nanocomposites N2 - Carbon black, multiwall carbon nanotubes, expanded graphite, multilayer graphene and graphene are compared comprehensively as flame retardants in nanocomposites to each other. Different polymer matrices are investigated as well as changing the concentration of the carbon fillers. Distinct combinations of graphene with conventional flame retardants are investigated. Phenomena and mechanisms are identified controlling the pyrolysis and fire behavior. The viscosity of the nanocomposites and their thermal conductivity as well are dramatically changed compared to the polymers influencing the time to ignition and flammability. During pyrolysis graphene functioned as inert filler and formed a residual protective layer reducing the peak heat release rate. The influence of graphene on the effectivity of various conventional halogen-free flame retardants depends strongly on their modes of action. The addition of a small amount of graphene to an intumescent flame retardant poly(propylene) led to an improvement in the cone calorimeter. The further increase of graphene content gained deceleration of swelling and a decrease of the final height of the intumescent layer. In combination with metal hydroxide, 1 wt% graphene closed the macroscopic surface structure and densified the microscopic structure of the fire residues tremendously. Due to this improved residue structure, metal hydroxides and graphene showed synergistic cooperation in terms of oxygen index and UL 94 classification (HB/V-1 to V-0). T2 - Rudolstädter Kunststoff-Tag CY - Rudolstadt, Germany DA - 12.10.2016 KW - Graphene KW - Nanocomposite KW - Flame retardant KW - Flammability KW - Pyrolysis PY - 2016 AN - OPUS4-38116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Flame and fire retardancy of polymer composites used in aviation N2 - The fire behaviour of carbon fibre (CF) reinforced polymers differs in comparison to polymers. Fibres behave often inert with respect to pyrolysis, they change the melt flow and dripping behaviour, the heat absorption and transfer, the amount and properties of the fire residue and so on. Flame and fire retardancy concepts are needed not only suitable for the different fire protection goals typical for each application, but also tailored for composites. This field is illuminated by examples taken from different projects carried out in the group of the author in the recent years. The examples target on different applications through achieving reduction in reaction to fire controlling the fire risks (flammability, heat release) in the beginning and development of a fire and investigating the fire stability, when a severe flame is directly applied (key property in fully developed fires). Approaches to halogen-free flame retardancy in CF reinforced thermosets are presented as well as building up a bench and an intermediate scale testing of composites in fire applying mechanical load (up to 1 MN compression) and direct flame exposure (180 kW/m2) simultaneously. Indeed, e.g. we have investigated the fire stability of stringer reinforced shell components taken out from the fuselage of an aircraft. The understanding of fire behaviour, fire resistance, and fire retardant modes of action in composites is a promising basis for target-oriented development. The role of flame inhibition, charring, and protective layer formation is discussed. Successful concepts are presented for fire retardancy tailored for different application as well as general guidelines for future development. Different phosphorus flame retardants are proposed to achieve halogen-free flame retardancy with respect to ignition and developing fires. Different protective approaches are sketched for addressing the fire stability of composites that is the most important fire risk for the fire resistance in structural applications. T2 - 7th EASN International Conference on Innovation in European Aeronautics Research CY - Warsaw, Poland DA - 26.09.2017 KW - Composite in Fire KW - Carbon fibre reinforced composite KW - Epoxy resin KW - Stringer reinforced shells KW - Fire stability KW - Flammability KW - Sandwich panels KW - Intumescence KW - Pyrolysis KW - Flame retardant PY - 2017 AN - OPUS4-42433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Flame Retardancy A Bunch of Thoughts N2 - The presentation gives an overview of actual research adtivities in the field of flame retardant polymers. Details are selected illuminating the scientific topic beyond the state of the art. Different concepts are illustrated with own results obtained in different Research projects over the last 15 years. T2 - public lecture at CIATEC CY - León, Guanajuato, México DA - 06.02.2019 KW - Flame retardant KW - Modes of action KW - Mechanisms KW - Fire testing KW - Pyrolysis KW - Calorimetry PY - 2019 AN - OPUS4-50078 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Flame Retardant Polyurethane: An Old, an Actual, and a Future Challenge N2 - This paper is based mainly on the results of two different projects performed in the group of the author recently (2016-2019). The three external partners involved in these two projects are competent in the preparation of FPUF (ICL IP America), RPUF (Department of Industrial Engineering, Padova University), and TPU (Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF, Darmstadt) as well as for the specimen preparation. Systematically varied sets of materials were prepared as the key basic for scientific discussion, varying the kind and combination of flame retardant, PUR structure, density, and blowing agent. A multimethodical approach based on thermogravimetry (TGA), TGA coupled with evolved gas analysis (TGA-FTIR) and pyrolysis GC-MS was used for investigating the pyrolysis. The flammability was addressed using oxygen index (OI) and testing in UL 94 burning chamber in vertical and horizontal set-up. The fire behaviour was addressed by using a cone calorimeter. Beyond these methods according to the state of the art, key experiments were performed. We addressed the dripping and the two-stage burning of TPU using a self-designed apparatus and specific data evaluation, the foam burning through quenching burning samples, using different special sample holders, and measuring temperature profiles within the burning foams. The investigation is made round by intensive analysis of the fire residues, such as comprehensive investigation of the morphology. Result on the pyrolysis (TGA-FTIR, Pyrolysis-GC/MS), flammability (UL 94, LOI), and fire behaviour (cone calorimeter) of TPU and flame retardant TPUs are shown. We discuss in detail the characteristic of PUR decomposition: the low tendency to char, and the specific two step decomposition and how these characteristics control the regimes in fire behaviour. We demonstrate that the different burning regimes are controlled by different pyrolysis products and effective heat of combustions. The resulting formation of pool fires as well as the formation of dripping is discussed in detail. The latter quite important to understand the flame retardancy applied with respect to achieve the UL 94 classification V0 nondripping or V0 non-flaming dripping. Rigid and flexible PUR foams and their flame retarded versions are investigated for different densities. Water and pentane-blown foams are compared as well as PUR and polyisocyanurate-polyurethane (PIR) foams. Horizontal testing in the cone calorimeter is used and the vertical foam specimen holder as well. Self-designed set-ups within the cone calorimeter enable a better inside in the pyrolysis front running through the foam samples as well as the development of the temperature gradient inside the foam during the fire test. The morphology change during burning was characterised by the means of quenching burning foams with liquid nitrogen and investigating the cross sections with scanning electron microscope. In sum, a rather comprehensive study was performed to work out the principle fire phenomena controlling the fire behaviour of PUR foams in a very systematic and significant way. Promising flame retardancy approaches are discussed. The importance of either combining the drain of fuel and flame inhibition or charring into an effective protection layer/multicellular structure is underlined. This contribution focusses the general conclusions and trends. It tries to increase the understanding of the specific and demanding challenge to develop flame retardant PUR materials. T2 - Interflam 2019, 15th International Interflam Conference CY - Egham, UK DA - 01.07.2019 KW - Polyurethane KW - Flame retardant KW - Dripping KW - Flammability KW - Pool fire KW - Pyrolysis KW - Decomposition KW - Foams PY - 2019 AN - OPUS4-48557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -