TY - JOUR A1 - Strommer, Bettina A1 - Battig, Alexander A1 - Schulze, Dietmar A1 - Agudo Jacome, Leonardo A1 - Schartel, Bernhard A1 - Böhning, Martin T1 - Shape, orientation, interaction, or dispersion: valorization of the influence factors in natural rubber nanocomposites N2 - The addition of nanoparticles as reinforcing fillers in elastomers yields nanocomposites with unique property profiles, which opens the door for various new application fields. Major factors influencing the performance of nanocomposites are studied by varying the type and shape of nanoparticles and their dispersion in the natural rubber matrix. The industrial applicability of these nanocomposites is put into focus using two types of graphene and a nanoscale carbon black, all commercially available, and scalable processing techniques in the form of a highly filled masterbatch production via latex premixing by simple stirring or ultrasonically assisted dispersing with surfactant followed by conventional two-roll milling and hot pressing. Different processing and measurement methods reveal the potential for possible improvements: rheology, curing behavior, static and dynamic mechanical properties, swelling, and fire behavior. The aspect ratio of the nanoparticles and their interaction with the surrounding matrix prove to be crucial for the development of superior nanocomposites. An enhanced dispersing method enables the utilization of the improvement potential at low filler loadings (3 parts per hundred of rubber [phr]) and yields multifunctional rubber nanocomposites: two-dimensional layered particles (graphene) result in anisotropic material behavior with strong reinforcement in the in-plane direction (157% increase in the Young's modulus). The peak heat release rate in the cone calorimeter is reduced by 55% by incorporating 3 phr of few-layer graphene via an optimized dispersing process. KW - Graphene KW - Natural rubber KW - Nanocomposites KW - Anisotropy KW - Fire behavior PY - 2023 DO - https://doi.org/10.5254/rct.23.77961 SN - 0035-9475 SN - 1943-4804 VL - 96 IS - 1 SP - 40 EP - 58 PB - Allen Press CY - Lawrence (KA), USA AN - OPUS4-57568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sanchez Olivares, G. A1 - Rockel, Daniel A1 - Calderas, F. A1 - Schartel, Bernhard T1 - Utilizing leather fibers from industrial wastes as bio-filler to improve flame retardancy in polypropylene N2 - Combining buffing leather fibers from industrial waste streams with ammonium polyphosphate and bentonite clay is proposed as a flame-retardant additive for polypropylene. The paper addresses how they can be processed into attractive composites with the desired mechanical properties. Buffing leather fibers function as a multifunctional bio-filler and as a synergist for the flame retardant, resulting in fire retardancy successful enough to increase the oxygen index (LOI) by up to 7 vol.-% and to achieve a V0 UL 94 classification. Impressively reduced heat release rates are obtained in the cone calorimeter at 50 kW/m2 irradiation; for instance, the maximum average rate heat evolved (MARHE) drops from 765 to below 200 kW m􀀀 2. The synergistic effects are quantified and shown to be very strong for LOI and MARHE. This work opens the door to use waste buffing leather fibers as a promising multifunctional and synergistic bio-filler. KW - Polypropylene KW - Flame retardancy KW - Industrial waste KW - Leather fibers KW - Bio-filler PY - 2024 DO - https://doi.org/10.1016/j.jiec.2023.11.008 SN - 1226-086X SN - 1876-794X VL - 132 SP - 148 EP - 160 PB - Elsevier B.V. AN - OPUS4-59556 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pappalardo, Salvatore A1 - Russo, Pietro A1 - Acierno, Domenico A1 - Rabe, Sebastian A1 - Schartel, Bernhard T1 - The synergistic effect of organically modified sepiolite in intumescent flame retardant polypropylene N2 - The pyrolysis, flammability and fire behavior of polypropylene (PP) containing an intumescent flame retardant and sepiolite nanoparticles were investigated by performing thermogravimetry, oxygen index (LOI), UL-94, and cone calorimeter tests. The combination of 0.5 wt% of premodified sepiolite (OSEP) with 12 wt% of a commercial intumescent flame retardant showed a clear synergy in LOI, UL-94 ranking and peak heat release rate. The ternary formulation achieved a V-0 classification and, consequently, allowed a reduction in the amount of flame retardant necessary to achieve this result. Whereas OSEP and pristine sepiolite nanoparticles (SEP) affect the performance in PP nanocomposites quite similarly, OSEP outperformed SEP in the combination with intumescent flame retardant. The cone calorimeter results and dynamic rheological measurements confirmed the synergistic effect between the nanofiller and the flame retardant resulting from the improved properties of the residual protective layer. KW - Polypropylene KW - Intumescent flame retardant KW - Sepiolite KW - Cone calorimetry KW - Low oxygen index PY - 2016 DO - https://doi.org/10.1016/j.eurpolymj.2016.01.041 SN - 0014-3057 VL - 76 SP - 196 EP - 207 PB - Elsevier AN - OPUS4-35854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sut, Aleksandra A1 - Greiser, Sebastian A1 - Jäger, Christian A1 - Schartel, Bernhard T1 - Interactions in multicomponent flame-retardant polymers: Solid-state NMR identifying the chemistry behind it N2 - Distinct approaches are used to reduce the fire risks of polymers, a key issue for many industrial applications. Among the variety of approaches, the use of synergy in halogen-free multicomponent systems is one of the most auspicious. To optimize the composition of such flame-retardant systems it is essential to understand the mechanisms and the corresponding chemistry in the condensed phase. In this work different methods are used, including cone calorimeter, thermogravimetry (TG), and TG-FTIR, with the main focus on the solid-state NMR analysis of the solid residues. The structural changes in the condensed phase of two thermoplastic elastomer systems based on copolymer styrene-ethylene-butadiene-styrene (TPE-S) were investigated: TPE-S/aluminium diethylphosphinate (AlPi)/magnesium hydroxide (MH) and TPE-S/AlPi/zinc borate (ZB)/poly(phenylene oxide) (PPO). Strong flame inhibition is synergistically combined with protective layer formation. 13C-, 27Al-, 11B- and 31P MAS NMR (magic angle spinning nuclear magnetic resonance) experiments using direct excitation with a single pulse and 1H–31P cross-polarization (CP) were carried out as well as double resonance techniques. Magnesium phosphates were formed during the pyrolysis of TPE-S/AlPi/MH, while for the system TPE-S/AlPi/ZB/PPO zinc phosphates and borophosphates were observed. Thus, the chemistry behind the chemical interaction was characterized unambiguously for the investigated systems. KW - Synergy KW - Solid-state NMR KW - Flame retardancy KW - SEBS KW - Aluminium diethylphosphinate KW - Magnesium hydroxide KW - Zinc borate KW - Poly(phenylene) oxide PY - 2015 DO - https://doi.org/10.1016/j.polymdegradstab.2015.08.018 SN - 0141-3910 SN - 1873-2321 VL - 121 SP - 116 EP - 125 PB - Applied Science Publ. CY - London AN - OPUS4-34306 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 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 - JOUR A1 - Sut, Aleksandra A1 - Greiser, Sebastian A1 - Jäger, Christian A1 - Schartel, Bernhard T1 - Aluminium diethylphosphinate versus ammonium polyphosphate: A comprehensive comparison of the chemical interactions during pyrolysis in flame-retarded polyolefine/poly(phenylene oxide) N2 - A systematic comparison of chemical interactions and fire behaviour is presented for the thermoplas-tic elastomer (block copolymer styrene-ethylene-butadiene-styrene) (TPE-S)/diethyl- and methylvinylsiloxane (Si)/poly(phenylene oxide) (PPO), flame-retarded with aluminium diethylphosphinate (AlPi)and with ammonium polyphosphate (APP), respectively. TPE-S/APP/Si/PPO performed better in the conecalorimeter test (reduction in peak heat release rate from 2042 to 475 kW m−2), but TPE-S/AlPi/Si/PPO inthe flammability tests (oxygen index (OI) and UL 94). This difference was caused by the different modes ofaction of APP (more in the condensed phase) and AlPi (mainly in the gas phase). Thermogravimetry cou-pled with Fourier transform infrared spectroscopy (TG-FTIR) was used to analyse the mass loss and theevolved gas products, while a Linkam hot-stage cell to investigate the decomposition in the condensedphase. Moreover, a detailed analysis of the fire residues was done using solid-state NMR.13C MAS NMRshowed that both flame-retarded compositions form graphite-like amorphous carbonaceous char, orig-inating from PPO.31P MAS NMR and29Si MAS NMR delivered important information about interactionbetween phosphorus and the siloxane. For TPE-S/AlPi/Si/PPO aluminium phosphate and silicon dioxideoccurred, while also silicophosphate was produced in TPE-S/APP/Si/PPO. The direct comparison of two ofthe most prominent halogen-free flame retardants containing phosphorus delivered meaningful insightsinto the modes of action and molecular mechanisms controlling flame retardancy. KW - Aluminium diethylphosphinate KW - Ammonium polyphosphate KW - Flame retardancy KW - Solid-state NMR KW - SEBS PY - 2016 SN - 0040-6031 SN - 1872-762X VL - 640 SP - 74 EP - 84 PB - Elsevier AN - OPUS4-37802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frasca, Daniele A1 - Schulze, Dietmar A1 - Böhning, Martin A1 - Krafft, Bernd A1 - Schartel, Bernhard T1 - Multilayer graphene chlorine isobutyl isoprene rubber nanocomposites: influence of the multilayer graphene concentration on physical and flame-retardant properties N2 - In recent years, different nanoparticles have been proposed and successfully introduced as nanofillers in rubber nanocomposites. In this study, multilayer graphene (MLG) is proposed as a nanoparticle that functions efficiently at low concentrations. MLG consists of just 10 or so graphene sheets. Chlorine isobutyl isoprene rubber (CIIR)/MLG nanocomposites with different MLG loadings were prepared using an ultrasonically assisted solution mixing procedure followed by two-roll milling. The incorporation of MLG provides a clear improvement in the rheological, mechanical, curing, and gas barrier properties of the nanocomposites. Adding only 3 phr ofMLGto CIIR increased the Young’s modulus by more than two times and reduced the permeability ofO2 andCO2 by 30%. Higher nanofiller concentrations yielded further improvement in the properties of the nanocomposites. Moreover, CIIR/MLG nanocomposites showed reduced flammability. KW - Graphene KW - Rubber KW - Nanocomposites KW - Flammability KW - Reinforcement PY - 2016 DO - https://doi.org/10.5254/rct.15.84838 SN - 0035-9475 VL - 89 IS - 2 SP - 316 EP - 334 AN - OPUS4-37595 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zirnstein, Benjamin A1 - Tabaka, Weronika A1 - Frasca, Daniele A1 - Schulze, Dietmar A1 - Schartel, Bernhard T1 - Graphene / hydrogenated acrylonitrile-butadiene rubber nanocomposites: Dispersion, curing, mechanical reinforcement, multifunctional filler N2 - Elastomers are usually mechanically reinforced with high loadings of carbon black (CB) to achieve the properties demanded; high amounts of mineral flame retardants are used to fulfill fire safety requirements. In this study, multilayer graphene (MLG), a nanoparticle made of only 10 graphene sheets, is applied in low loadings, 3 parts per hundred rubber (phr) to reduce the total amount of filler or boost performance in hydrogenated acrylonitrilebutadiene rubber (HNBR). In the HNBR/MLG nanocomposites, 3 phr MLG replaced 15 phr CB, 3 phr aluminum trihydroxide (ATH), or 15 phr CB + 3 phr ATH. The nanocomposites were prepared via master batch by ultrasonically assisted solution mixing and subsequent conventional two-roll milling. A comprehensive study is presented, illustrating the impact of MLG on curing and mechanical properties; e.g. replacing 2.5 phr ATH with 3 phr MLG increased the Young's modulus by over 60% and hardness by 10%, while improving flame retardancy, and reducing the total heat evolved by 10%. MLG is a multifunctional filler, as demonstrated by various enhancements in terms of the mechanical and flame retardancy properties of the rubber composites. KW - Nanocomposite KW - Rubber KW - Graphene PY - 2018 DO - https://doi.org/10.1016/j.polymertesting.2018.01.035 SN - 0142-9418 SN - 1873-2348 VL - 66 SP - 268 EP - 279 PB - Elsevier Ltd. AN - OPUS4-44457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qiu, Y. A1 - Wachtendorf, Volker A1 - Klack, Patrick A1 - Qian, L. A1 - Liu, Z. A1 - Schartel, Bernhard T1 - Improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene/triazine compounds in epoxy thermoset N2 - A siloxane compound (MVC) and a bi-group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy thermosets to explore high-efficiency flame retardant systems. With only 1wt% MVC and 3wt% TGD, an epoxy thermoset passed UL 94 V-0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combinedwith condensed-phase pyrolysis product Analysis jointly revealed the details of the changed pyrolysis mode. KW - Flame retardant KW - Epoxy resin KW - Synergy KW - Siloxane KW - DOPO KW - Triazine PY - 2017 DO - https://doi.org/10.1002/pi.5466 SN - 0959-8103 SN - 1097-0126 VL - 66 IS - 12 SP - 1883 EP - 1890 PB - Wiley AN - OPUS4-42950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zirnstein, Benjamin A1 - Schulze, Dietmar A1 - Schartel, Bernhard T1 - The impact of polyaniline in phosphorus flame retardant ethylene-propylene-diene-rubber (EPDM) N2 - Usually elastomers are loaded with high amounts of flame retardants to fulfill fire safety requirements. In this study the potential char precursor polyaniline (PANI) and the established fire retardant pentaerythritol (PER) were implemented in ethylene-propylene-diene monomer rubber (EPDM). PANI and PER were used in low loadings (7 phr) and combined with two phosphorous flame retardants, Ammonium polyphosphate (APP) and a piperazine-pyrophosphate/phosphoric acid compound (FP), to boost their performance. A comprehensive study is presented, explaining the impact of PANI on curing and mechanical properties, including compensation for the plasticizer-like effect of APP in EPDM, and improved flame retardancy. In the cone calorimeter test, the combination of EPDM/FP/PANI reduced the effective heat of combustion by 20%. All nine EPDM rubber compounds were investigated with the LOI and UL 94 tests, cone calorimeter, FMVSS 302 and glow wire testing to quantify fire performance. The PANI containing EPDM rubbers, EPDM/APP/PANI and EPDM/FP/PANI outperformed the corresponding PER containing, EPDM/APP/PER and EPDM/FP/PER rubbers in various tests. Moreover, the study investigated the impact of PANI and PER on the mode of action of the phosphorus species and showed that the addition of PANI increased the amount of phosphorus in the condensed phase. To receive a broader understanding of the flame retardant mode of action of PANI in combination with APP and FP, calculations were carried out to estimate the impact of PANI on the protective layer effect. KW - EPDM KW - Rubber KW - Flame retardant KW - Polyaniline KW - Pentaerythritol PY - 2019 DO - https://doi.org/10.1016/j.tca.2019.01.019 SN - 0040-6031 VL - 673 SP - 92 EP - 104 PB - Elsevier B.V. AN - OPUS4-47503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -