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 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 - CONF A1 - Dittrich, Bettina T1 - Graphene - Adjuvant for Halogen-Free Flame Retardants? T2 - FRPM 2015, 15th European Meeting on Fire Retardancy and Protection of Materials CY - Berlin, Germany DA - 2015-06-22 PY - 2015 AN - OPUS4-33627 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - BOOK A1 - Schubert, Martina A1 - Schartel, Bernhard A1 - Lang, M. A1 - Yin, Huajie A1 - Dittrich, Bettina A1 - Heidemeyer, P. A1 - Bastian, Martin T1 - Wirkungsweise von halogenfreien Flammschutzmitteln in WPC N2 - Das Ziel des Forschungsvorhabens war die Untersuchung der Wirkungsweise von halogenfreien Flammschutzmitteln in WPC. Eine große Anzahl verschiedener Flammschutzmittel wurde hinsichtlich ihrer Wirkmechanismen umfassend untersucht, um ein Verständnis für die ablaufenden Prozesse zu entwickeln. Hierbei wurden verschiedene Brandtests eingesetzt, um die Materialien bezüglich verschiedener Applikationen (E&E, Transportwesen, Bauwesen) zu beleuchten. Die verschiedenen Untersuchungen liefern aber auch ein umfassendes Bild vom Brandverhalten in den verschiedenen Eigenschaften, wie Entflammbarkeit und Brandausbreitung. Die prinzipiellen Ansätze wurden anhand von verschiedenen Flammschutzmitteln beleuchtet, ihre Pyrolyse und ihre Performance in verschiedenen Brandtests gegenübergestellt. Bei der angestrebten geringen Zusatzmenge ist durch den Zusatz eines einzigen Flammschutzmittels keine zufriedenstellende Reduktion der Brandeigenschaften zu erwarten. Multikomponentensysteme zur Steigerung der Effizienz sind angezeigt. Einige prinzipielle Kombinationsmöglichkeiten wurden für alle Hauptflammschutzmittel durchgespielt. Die teilweise deutlichen Verbesserungen zeigen Wege zur erfolgreichen Produktentwicklung auf. So konnten bei den Spritzgießcompounds Eigenschaften erzielt werden, die eine UL 94 V0 Klassifizierung ermöglichen. Ein Einsatz der im Forschungsvorhaben hergestellten Compounds als Baustoff ist aufgrund des Brandverhaltens in den baustoffspezifischen Prüfungen nicht möglich. Hier sind weitere Flammschutz-Konzepte zu erproben. Gleitmittel nehmen bei den untersuchten Extrusionscompounds keinen Einfluss auf das Brandverhalten. Haftvermittler nehmen ebenfalls keinen signifikanten Einfluss auf das untersuchte Brandverhalten, können aber zu einer veränderten Verteilung der Füllstoffe und damit zur Ausbildung einer effektiveren Schutzschicht führen. Feinere Holzpartikel schneiden bei den Brandprüfungen besser ab als grobe Holzpartikel. Bei Einsatz von grobem Holz wird eine schlechtere Rückstandsstruktur ausgebildet, was das Brandverhalten negativ beeinflusst. Der Einsatz von vorbehandeltem Holz brachte nicht die erwartete Verbesserung. Die neu konzipierte Aufbereitungsanlage auf Basis des Planetwalzenextruders konnte erfolgreich in Betrieb genommen werden. Vergleichende Versuche mit dem Doppelschneckenextruder zeigten, dass der PWE-Aufbau eine gute Alternative zur etablierten DSE-Aufbereitung darstellt. Zusätzlich wurden an Compounds vielversprechender Flammschutzansätze weitere Materialprüfungen (Biegeversuch, Schlagversuch, Wasseraufnahme) durchgeführt, um den Einfluss der FSM auf die spezifischen Eigenschaften der WPC zu beleuchten. N2 - The objective of the research project was to investigate the effect of halogen-free flame retardants in WPC. A large number of different flame retardants was thoroughly examined regarding their effect mechanisms to develop an understanding for the processes taking place. Different fire tests were used to examine the materials with respect to the different applications (E&E, transportation, construction). Additionally, the different investigations provide a comprehensive picture of the fire behavior regarding the different properties, such as flammability and fire spread. The fundamental approaches were examined by means of different flame retardants and their pyrolysis and performance were compared in different fire tests. A satisfactory reduction of the fire properties by adding only one flame retardant cannot be expected with the intended low added amount. Multi-component systems to increase the efficiency are indicated. Some basic combination options were tried out for all main flame retardants. The partially considerable improvements illustrate ways for successful product development. This way, properties could be achieved in injection molding compounds, which allow for a UL 94 V0 classification. It is not possible to use the compounds introduced in the research project as building material due to the fire behavior in the building material specific tests. Further flame protection concepts need to be tested in this area. Slip agents do not have an influence on the fire behavior of the examined extrusion compounds. Adhesion promoters also do not have a significant influence on the examined fire behavior but can lead to a change in the distribution of the fillers and thus to the formation of a more effective protective layer. Finer wood particles performed better in the fire tests than coarse wood particles. When using coarse wood, an inferior residual structure is formed, which has an adverse effect on the fire behavior. The use of pretreated wood fibers did not bring the expected improvement. The newly conceived processing technique based on a planetary roller extruder (PRE) was successfully put into operation. Comparative tests with twin-screw extruders (TSE) showed that the PRE configuration is a good alternative to the established TSE processing. Additionally, further material testing (bending test, impact test, water absorption) was performed on promising flame retarded compounds to examine the influence of the fire retardants on the specific properties of the WPC. KW - Wood plastic composite KW - Halogen free KW - Flame retardancy PY - 2016 SN - 978-3-8440-4645-8 SN - 2364-754X SP - 1 EP - 88 PB - Shaker Verlag CY - Aachen AN - OPUS4-37482 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwarzer, M. A1 - Korwitz, A. A1 - Komber, H. A1 - Häußler, L. A1 - Dittrich, Bettina A1 - Schartel, Bernhard A1 - Pospiech, D. T1 - Phosphorus-containing polymer flame retardants for aliphatic polyesters N2 - Polyesters with 9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide-containing comonomers are synthesized aiming to improve the flame retardancy of aliphatic polyesters such as poly(butylene succinate) and poly(butylene sebacate). The influence of the chemical structure on the thermal decomposition and pyrolysis is examined using a combination of thermogravimetric analysis (TGA), TGA-Fourier transform infrared (FTIR) spectroscopy, pyrolysis-gas chromatography/mass spectrometry, and microscale combustion flow calorimetry. Thermal decomposition pathways are derived and used to select suitable candidates as flame retardants for PBS. The fire behavior of the selected polymers is evaluated by forced-flaming combustion in a cone calorimeter. The materials show two modes of action for flame retardancy: strong flame inhibition due to the release of a variety of molecules combined with charring in the solid state. KW - Synthesis KW - Flame retardant KW - Aliphatic polyester KW - DOPO PY - 2018 DO - https://doi.org/10.1002/mame.201700512 SN - 1438-7492 SN - 1439-2054 VL - 303 IS - 2 SP - 1700512-1 EP - 1700512-16 PB - Wiley VCH Verlag AN - OPUS4-44334 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dittrich, Bettina T1 - Graphene - Promising Nanofiller and Adjuvant for Flame Retarded Composites T2 - MoDeSt 2014 CY - Portorož, Slovenia DA - 2014-08-31 PY - 2014 AN - OPUS4-31414 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scarfato, Paola A1 - Incarnato, L. A1 - Di Maio, L. A1 - Dittrich, Bettina A1 - Schartel, Bernhard T1 - Influence of a novel organo-silylated clay on the morphology, thermal and burning behavior of low density polyethylene composites N2 - The functionalization of a natural sodium montmorillonite (MMT) with (3-glycidyloxypropyl)trimethoxysilane by a silylation procedure is presented, and its use as nanofiller in the melt compounding of low density polyethylene (LDPE) nanocomposites. In particular, the effects on the thermal stability and flame retardant properties of melt compounded LDPE nanocomposites are analyzed, with and without magnesium hydroxide (MH) as an additional conventional flame retardant. The purpose was to investigate possible synergistic effects between the two inorganic fillers on fire behavior. The obtained organosilylated clay showed higher interlayer spacing than the original MMT and good thermal stability, higher than that of many commercial organoclays modified with alkylammonium salts. Its addition to LDPE allowed the production of hybrids with nanoscale dispersion of the filler, as demonstrated by X-ray diffraction. The simultaneous presence of MH, which strongly interacts with the nanoclay, hindered intercalation of the polymer chains between the clay galleries and clay layer exfoliation within the LDPE resin. The investigation of the thermal and burning behavior of the LDPE nanocomposites indicated that the organosilylated clay alone shows only a limited residual protection layer effect. In combination with MH the nanocomposites have a small adverse effect on the reaction to small flame as measured by the Oxygen index and UL 94 testing, and, surprisingly, no effect on the peak heat release rate in the cone calorimeter. The quality of the fire residue was lacking on the microscopic scale. The ternary LDPE/MH/ organoclay systems investigated did not open the door to reducing MH content in halogen-free flame retardant LDPE yet, but demand further research. KW - Nano structures KW - Polymer-matrix composites KW - High-temperature properties KW - Thermoplastic resin KW - Burning behavior KW - Fire retardancy PY - 2016 DO - https://doi.org/10.1016/j.compositesb.2016.05.053 SN - 1359-8368 VL - 98 SP - 444 EP - 452 PB - Elsevier AN - OPUS4-36865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dittrich, Bettina A1 - Wartig, K.-A. A1 - Hofmann, D. A1 - Mülhaupt, R. A1 - Schartel, Bernhard T1 - The influence of layered, spherical, and tubular carbon nanomaterials' concentration on the flame retardancy of polypropylene N2 - The characteristic influences of increasing concentrations of graphene, expanded graphite (EG), carbon black (CB), and multiwall carbon nanotubes (MWNT) are investigated on pyrolysis, reaction to small flame, burning behavior, and on electrical, thermal, and rheological properties of flame retarded polypropylene (PP-FR). The property-concentration dependency is different for the various material properties, as threshold, linear, and leveling off functions were observed. Increasing concentrations of carbon nanoparticles resulted in a decrease in the electrical resistivity of the polymer by crossing the percolation threshold. The developing nanoparticle network changes melt flow behavior for small shear rates, increases thermal conductivity and therefore, affects the UL 94 classification and oxygen index. The onset temperature of PP decomposition is shifted to temperatures up to 37°C higher; the peak heat release rate is reduced by up to 74% compared to PP-FR. Both effects leveled off with increasing particle concentration. Among the four carbon nanomaterials tested, graphene presents superior influence on composite properties over the tested concentration range and outperforms commercial CB, MWNT, and EG. POLYM. COMPOS., 36:1230–1241, 2015. KW - Graphene KW - Flame retardancy KW - Concentration dependency KW - Nanocomposite KW - Carbon nanomaterial PY - 2015 DO - https://doi.org/10.1002/pc.23027 SN - 0272-8397 SN - 1548-0569 VL - 36 IS - 7 SP - 1230 EP - 1241 PB - Society of Plastics Engineers CY - Manchester, NH AN - OPUS4-33619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - Dittrich, Bettina A1 - Farooq, Muhammad A1 - Kerling, S. A1 - Wartig, K.-A. A1 - Hofmann, D. A1 - Huth, Christian A1 - Okolieocha, C. A1 - Altstädt, V. A1 - Schönhals, Andreas A1 - Schartel, Bernhard T1 - Carbon-based nanofillers/poly(butylene terephthalate): thermal, dielectric, electrical and rheological properties N2 - The influence of distinct carbon based nanofillers: expanded graphite (EG), conducting carbon black (CB), thermally reduced graphene oxide (TRGO) and multi-walled carbon nanotubes (CNT) on the thermal, dielectric, electrical and rheological properties of polybutylene terephthalate (PBT) was examined. The glass transition temperature (Tg) of PBT nanocomposites is independent of the filler type and content. The carbon particles act as nucleation agents and significantly affect the melting temperature (Tm), the crystallization temperature (Tc) and the degree of crystallinity of PBT composites. PBT composites with EG show insulating behaviour over the tested concentration range of 0.5 to 2 wt.-% and hardly changed rheological behaviour. CB, CNT and TRGO induce electrical conductivity to their particular PBT composites by forming a conducting particle network within the polymer matrix. CNT reached the percolation threshold at the lowest concentration (<0.5 wt.-%), followed by TRGO (<1 wt.-%) and CB (<2 wt.-%). With the formation of a particle network, the flow behaviour of composites with CB, CNT and TRGO is affected, i.e., a flow limit occurs and the melt viscosity increases. The degree of influence of the carbon nanofillers on the rheological properties of PBT composites follows the same order as for electrical conductivity. Electrical and rheological results suggest an influence attributed to the particle dispersion, which is proposed to follow the order of EG<< CB31 vol%). TRGO strengthens the residue structure of MH and therefore functions as a strong synergist in terms of OI and UL 94 classification (from HB to V-0). KW - Graphene KW - Intumescence KW - Ammonium polyphosphate KW - Magnesium hydroxide KW - Synergy KW - Polypropylene PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-320685 DO - https://doi.org/10.3390/polym6112875 SN - 2073-4360 VL - 6 IS - 11 SP - 2875 EP - 2895 PB - MDPI CY - Basel AN - OPUS4-32068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -